TY - CHAP A1 - Altenberger, Igor A1 - Noster, Ulf A1 - Nalla, Ravi K. A1 - Ritchie, Robert O. A1 - Scholtes, Berthold T1 - Residual stress relaxation in fatigue of mechanically surface treated materials T2 - Proceedings 132nd Annual TMS Meeting, March 2–6, 2003, San Diego, California Y1 - 2003 UR - https://www.researchgate.net/publication/273462779_Residual_stress_relaxation_in_fatigue_of_mechanically_surface_treated_materials SP - 312 ER - TY - JOUR A1 - Jahn, Hannes A1 - Böhm, Valter A1 - Zentner, Lena T1 - Analysis of deformation in tensegrity structures with curved compressed members JF - Meccanica N2 - AbstractTensegrity structures are prestressed structures consisting of compressed members connected by prestressed tensioned members. Due to their properties, such as flexibility and lightness, mobile robots based on these structures are an attractive subject of research and are suitable for space applications. In this work, a mobile robot based on a tensegrity structure with two curved members connected by eight tensioned strings is analyzed in terms of deformation in the curved members. Further, the difference in locomotion trajectory between the undeformed and deformed structure after the prestress is analyzed. For that, the theory of large deflections of rod-like structures is used. To determine the relationship between acting forces and the deformation, the structure is optimized using minimization algorithms in Python. The results are validated by parameter studies in FEM. The analysis shows that the distance between the two curved members significantly influences the structure’s locomotion. It can be said that the deformation of the components significantly influences the locomotion of tensegrity structures and should be considered when analyzing highly compliant structures. KW - Rolling locomotion KW - Mobile robot KW - Tensegrity structures KW - Deformation of compressedmembers KW - Finite element simulations Y1 - 2024 U6 - https://doi.org/10.1007/s11012-024-01833-y SN - 0025-6455 PB - Springer Nature ER - TY - CHAP A1 - Herrmann, David A1 - Schaeffer, Leon A1 - Schmitt, Lukas A1 - Körber, Wolfgang A1 - Merker, Lukas A1 - Zentner, Lena A1 - Böhm, Valter T1 - Compliant Robotic Arm based on a Tensegrity Structure with x-shaped Members T2 - 2024 IEEE 7th International Conference on Soft Robotics (RoboSoft), San Diego, CA, USA. April 14-17, 2024 N2 - The use of intrinsically compliant tensegrity structures in manipulation systems is an attractive research topic. In this paper a 3D compliant robotic arm based on a stacked tensegrity structure consisting of x-shaped rigid members is considered. The rigid members are interconnected by a net of prestressed, tensioned members with pronounced intrinsic elasticity and by inelastic tensioned members. The system's motion is achieved by length-change of the inelastic tensioned members. The operating principle of the system is discussed with the help of kinematic considerations and verified by experiments. KW - Geometry KW - Three-dimensional displays KW - Shape KW - Prototypes KW - Kinematics KW - Soft robotics KW - Manipulators Y1 - 2024 U6 - https://doi.org/10.1109/RoboSoft60065.2024.10521941 SP - 1047 PB - IEEE ER - TY - GEN A1 - Rieffel, John A1 - Herrmann, David A1 - Lehmann, Lukas A1 - Schaeffer, Leon A1 - Böhm, Valter ED - Flores, Paulo ED - Marques, Filipe ED - Da Rodrigues Silva, Mariana T1 - Illuminating the morphological diversity of 2D tensegrity grids T2 - MMT Symposium (Mechanism and Machine Theory Symposium): Book of Abstracts ; June 26-28, 2024. - Guimarães, Portugal Y1 - 2024 UR - https://mmtsymposium.com/wp-content/uploads/2024/07/mmtsymposium_bookofabstracts.pdf SN - 978-989-33-6448-2 IS - 1. edition SP - 457 EP - 458 PB - Departamento de Engenharia Mecânica, Universidade do Minho CY - Guimarães, Portugal ER - TY - CHAP A1 - Merker, Lukas A1 - Böhm, Valter A1 - Zentner, Lena T1 - Modellbildung und Steifigkeitsanalyse eines nachgiebigen Tensegrity-ähnlichen Koppelelements T2 - 15. Kolloquium Getriebetechnik, 2023, Aachen Y1 - 2023 SP - 63 EP - 66 PB - Verlag Mainz CY - Aachen ER - TY - JOUR A1 - Launhardt, M. A1 - Wörz, A. A1 - Loderer, A. A1 - Laumer, Tobias A1 - Drummer, Dietmar A1 - Hausotte, Tino A1 - Schmidt, Michael T1 - Detecting surface roughness on SLS parts with various measuring techniques JF - Polymer Testing N2 - Selective Laser Sintering (SLS) is an additive manufacturing technique whereby a laser melts polymer powder layer by layer to generate three-dimensional parts. It enables the fabrication of parts with high degrees of complexity, nearly no geometrical restrictions, and without the necessity of a tool or a mold. Due to the orientation in the building space, the processing parameters, and the powder properties, the resulting parts possess an increased surface roughness. In comparison to other manufacturing techniques, e.g. injection molding, the surface roughness of SLS parts results from partially melted powder particles on the surface layer. The actual surface roughness must thus be characterized with respect to the part's eventual application. At the moment, there is no knowledge regarding which measuring technique is most suitable for detecting and quantifying SLS parts' surface roughness. The scope of this paper is to compare tactile profile measurement methods, as established in industry, to optical measurement techniques such as Focus Variation, Fringe Projection Technique (FPT), and Confocal Laser Scanning Microscope (CLSM). The advantages and disadvantages of each method are presented and, additionally, the effect of tactile measurement on a part's surface is investigated. KW - Selective Laser Sintering (SLS) KW - PA12 KW - Surface roughness KW - Measuring technique Y1 - 2016 SN - 0142-9418 U6 - https://doi.org/10.1016/j.polymertesting.2016.05.022 SN - 1873-2348 VL - 53 SP - 217 EP - 226 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hupfeld, T. A1 - Laumer, Tobias A1 - Stichel, T. A1 - Schuffenhauer, T. A1 - Heberle, J. A1 - Schmidt, Michael A1 - Barcikowski, S. A1 - Gökce, B. T1 - A new approach to coat PA12 powders with laser-generated nanoparticles for selective laser sintering JF - Procedia CIRP N2 - The modification of selective laser sintering (SLS) powder materials by nanoadditives offers the possibility to adapt the powder properties to the laser sintering process or the resulting part properties. To avoid agglomeration of the nanofiller, a new approach in which surfactant-free laser-generated colloidal nanoparticles are adsorbed onto the polymer surface directly in an aqueous solution is demonstrated. Based on this novel approach, polyamide 12 (PA12) powders are decorated with metal and oxide nanoparticles and processed via SLS. Electron microscopy and confocal laser scanning imaging are utilized to analyze the dispersion of the filler. KW - laser additive manufacturing KW - nanoparticles KW - polymer powders KW - pulsed laser ablation in liquids KW - selective laser sintering Y1 - 2018 U6 - https://doi.org/10.1016/j.procir.2018.08.103 VL - 74 SP - 244 EP - 248 PB - Elsevier ER - TY - JOUR A1 - Laumer, Tobias A1 - Stichel, T. A1 - Nagulin, K. A1 - Schmidt, Michael T1 - Optical analysis of polymer powder materials for Selective Laser Sintering JF - Polymer Testing N2 - This study increases the basic understanding of optical material properties of polymer powders used in selective laser sintering (SLS). Therefore, different polymer powder materials were analyzed regarding their optical material properties with an integration spheres measurement setup. By the measurements a direct connection between the absorption behavior of the solid material and the overall optical material characteristics of the same material in powdery form could be shown. The results were used to develop an advanced explanation model for the optical material properties of powders. At present, existing explanation models only consider the occurring of multiple reflections in the gaps between the particles to explain the overall optical material properties of powder materials. Thus, by also considering the absorption behavior of the single particles, the basic understanding of the beam-matter interaction and their effect on the optical material properties of powder materials can be expanded. KW - Additive manufacturing KW - Selective Laser Sintering KW - Optical material characteristics KW - Integration spheres KW - Material qualification KW - New materials Y1 - 2016 U6 - https://doi.org/10.1016/j.polymertesting.2016.10.010 SN - 1873-2348 SN - 0142-9418 VL - 56 SP - 207 EP - 213 PB - Elsevier Science CY - Amsterdam [u.a.] ER - TY - GEN A1 - Chavez Vega, Jhohan Harvey A1 - Böhm, Valter A1 - Yin, J. A1 - Becker, Tatiana I. A1 - Köhring, Sebastian A1 - Monkman, Gareth J. A1 - Odenbach, Stefan A1 - Zimmermann, Klaus T1 - Field induced plasticity of magneto-sensitive elastomers for gripping technology applications T2 - 6th Colloquium of SPP 1681, Benediktbeuern, 26. - 28.09.2018 : Book of Abstracts Y1 - 2018 SP - 16 EP - 17 ER - TY - GEN A1 - Krenkel, Lars A1 - Michel, Johanna A1 - Keil, Niklas A1 - Daschner, Jan T1 - Experimental Investigation of Logitudinal Folds in Endotracheal Tube Cuffs and their Correlation to Silent Breathing T2 - 23. DGLR Fach-Symposium Strömungen mit Ablösung, 09./10. November 2022, Berlin, Deutschland N2 - Air leakage past High-Volume-Low-Pressure (HVLP) endotracheal tube (ETT) cuffs creates a potential infection risk for health care professionals during ventilation of patients suffering from contagious airborne diseases. However, unlike silent aspiration, a phenomenon where fluids enter the airways of intubated patients, the aspect of aerosol emergence through cuff folds -what we called accordingly “silent breathing” (SB)- has not been investigated in detail so far. This study investigates air leakage past HVLP cuffs with varying cuff pressures under realistic artificial breathing scenarios experimentally and in addition numerically. The focus was laid on the parametric investigation of the occurrence and furthermore on different influencing factors of silent breathing. The morphology of the folds responsible for the leakage was captured using high-resolution 3D microcomputed tomography (μCT). For the numerical investigations (Com-putational Fluid Dynamics - CFD), the commercial CFD Software package FLUENT 2021 R2 (ANSYS, Inc., Canonsburg, PA, US), as well as the DLR in-house research code THETA has been used. KW - Silent Breathing KW - Aerosols KW - CFD KW - Endotracheal Intubation Y1 - 2022 UR - https://www.dlr.de/as/Portaldata/5/Resources/dokumente/veranstaltungen/stab_workshop/Jahresbericht2022.pdf CY - Göttingen ER - TY - CHAP A1 - Altenberger, Igor A1 - Nalla, Ravi K. A1 - Noster, Ulf A1 - Scholtes, Berthold A1 - Ritchie, Robert O. T1 - On the fatigue behavior and associated effect of residual stresses in deep rolled and laser shock peened Ti-6Al-4V at ambient and elevated temperatures T2 - 2003 TMS annual meeting N2 - Mechanical surface treatments, such as deep rolling, shot peening and laser shock peening, can significantly improve the fatigue behavior of highly stressed metallic components. Deep rolling is an especially attractive technique since it is possible to generate deep, near-surface compressive residual stresses and work hardening while retaining a relatively smooth surface finish. Indeed, this technique is best known for increasing the fatigue strength and lifetime of steel components such as crankshafts. Although most work on deep rolling has been on steels, recently it has also been applied with reasonable success to titanium alloys. Accordingly, in this investigation, we examine the effect of deep rolling on the high-cycle fatigue behavior of Ti-6Al-4V, with particular emphasis on the thermal and mechanical stability of the residual stress states and near-surface microstructures. Preliminary results on laser shock peened Ti-6Al-4V are also presented for comparison. In addition, we examine whether these surface treatments are effective in retaining fatigue strength at the higher temperatures of 300 to 450C. Based on the cyclic deformation and stress/life behavior, together with the X-ray and microstructural observations, it is found that deep rolling can be quite effective in retarding the initiation and initial propagation of fatigue cracks in Ti-6Al-4V at such higher temperatures, despite the almost complete relaxation of the residual stresses at the surface. This clearly implies that, in addition to residual stresses, near-surface microstructures, which in Ti-6Al-4V consist of ultrafine near-surface nanostructures, play a critical role in the enhancement of fatigue lifetimes by mechanical surface treatments. Y1 - 2003 UR - https://www.researchgate.net/publication/273462702_On_the_fatigue_behavior_and_associated_effect_of_residual_stresses_in_deep_rolled_and_laser_shock_peened_Ti-6Al-4V_at_ambient_and_elevated_temperatures SP - 359 PB - The Minerals, Metals & Materials Society (TMS) ER - TY - JOUR A1 - Haus, Moritz A1 - Foltan, Maik A1 - Philipp, Alois A1 - Müller, Thomas A1 - Lingel, Maximilian P. A1 - Krenkel, Lars A1 - Gruber, Michael A1 - Lehle, Karla T1 - Neutrophil extracellular traps -a potential trigger for the development of thrombocytopenia during extracorporeal membrane oxygenation N2 - Neutrophil extracellular traps (NETs) have recently emerged as a potential link between inflammation, immunity, and thrombosis, as well as other coagulation disorders which present a major challenge in the context of extracorporeal membrane oxygenation (ECMO). By examining blood from ECMO patients for NETs and their precursors and correlating them with clinical and laboratory biomarkers of coagulation and inflammation, this study aims to evaluate the association between the presence of NETs in the bloodstream of ECMO patients and the development of potentially severe coagulation disorders during ECMO therapy. Therefore, blood samples were collected from healthy volunteers (n=13) and patients receiving veno-venous (VV) ECMO therapy (n=10). To identify NETs and their precursors, DNA and myeloperoxidase as well as granulocyte marker CD66b were visualized simultaneously by immunofluorescence staining in serial blood smears. Differentiation of DNA-containing objects and identification of NETs and their precursors was performed semiautomatically by a specific algorithm using the shape and size of DNA staining and the intensity of MPO and CD66b signal. Neutrophil extracellular traps and their precursors could be detected in blood smears from patients requiring VV ECMO. Compared to volunteers, ECMO patients presented significantly higher rates of NETs and NET precursors as well as an increased proportion of neutrophil granulocytes in all detected nucleated cells. A high NET rate prior to the initiation of ECMO therapy was associated with both increased iL-6 and TNF-α levels as an expression of a high cytokine burden. These patients with increased NET release also presented an earlier and significantly more pronounced decrease in platelet counts and ATIII activity following initiation of therapy compared with patients with less elevated NETs. These findings provide further indications for the development of immune-mediated acquired thrombocytopenia in ECMO patients. KW - Neutrophil extracellular traps (NET) KW - Immunoflorescence KW - Thrombocytopenia KW - Extracorporeal membrane oxygenation (ECMO) KW - Sepsis KW - immunothrombosis KW - Coagulation disorder Y1 - 2024 UR - https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1339235/abstract U6 - https://doi.org/10.3389/fimmu.2024.1339235 VL - 15 PB - frontiers ER - TY - CHAP A1 - Schmid, Florian A1 - Galka, Stefan A1 - Marinkovic, Minja A1 - Meißner, Sebastian ED - Bergmann, Sören ED - Feldkamp, Niclas ED - Souren, Rainer ED - Straßburger, Steffen T1 - Simulationsbasierte Untersuchung von Abstraktionsgraden im Kontext Digitaler Zwillinge für innerbetriebliche Transportsysteme T2 - Tagungsband 20. ASIM-Fachtagung Simulation in Produktion und Logistik, Ilmenau, 13. – 15. September 2023 N2 - Current challenges in the planning and control of internal logistics systems are based on permanent changes in the requirements on the system, e.g., due to fluctuating order numbers or changes in their structure. For the representation and planning of in-house logistics processes, digital twins offer the possibility to verify different operational decisions such as predictive workforce scheduling. In this context, the quality of the results and their in-time presentation plays a decisive role. However, both target criteria are influenced by the detail-level of the digital representation. Based on a case study, this paper investigates the influence of the level of detail on the simulation runtime and result divergence to provide an evaluation for detail levels in the modelling of intralogistic transport systems. T2 - Simulation-based Analysis of Abstraction Degrees in the Context of Digital Twins for Intralogistics Transport Systems Y1 - 2023 SN - 978-3-86360-276-5 U6 - https://doi.org/10.22032/DBT.57794 SP - 135 EP - 144 PB - Universitätsverlag Ilmenau CY - Ilmenau ER - TY - CHAP A1 - Herrmann, David A1 - Schaeffer, Leon A1 - Zentner, Lena A1 - Böhm, Valter T1 - Theoretical considerations on 3D tensegrity joints for the use in manipulation systems T2 - Engineering for a changing world : 60th ISC, Ilmenau Scientific Colloquium, Technische Universität Ilmenau, September 4-8, 2023 N2 - This paper presents a comprehensive analysis of a three-dimensional compliant tensegrity joint structure, examining its actuation, kinematics, and response to external loads. The study investigates a baseline configuration and two asymmetric variants of the joint. The relationship between the shape parameter and the parameters of the tensioned segments is derived, enabling the mathematical description of cable lengths for joint actuation. Geometric nonlinear static finite element simulations are performed to analyze the joint's response under various load conditions. The results reveal the joint's range of motion, the effect of different stiffness configurations, and its deformation behavior under external forces. The study highlights the asymmetric nature of the joint and its potential for targeted motion restriction. These findings advance the general understanding of the behavior of the considered tensegrity joint and provide valuable insights for their design and application in soft robotic systems. Y1 - 2023 U6 - https://doi.org/10.22032/dbt.58888 SP - 1 EP - 13 PB - Technische Universität Ilmenau CY - Ilmenau ER - TY - CHAP A1 - Galka, Stefan A1 - Schmid, Florian A1 - Grasser, Dominik A1 - Hohm, Jonathan A1 - Stauber, Stephan A1 - Meißner, Sebastian T1 - Integration eines SAP-Transportleitsystem in eine Simulationsumgebung zur Unterstützung von Entscheidungen im operativen Betrieb T2 - Tagungsband 20. ASIM-Fachtagung Simulation in Produktion und Logistik, Ilmenau, 13. – 15. September 2023 N2 - Digital twins enable the digital representation of physical systems and provide comprehensive modelling and analysis capabilities. An online data exchange between the Digital twin and SAP is feasible, through integration of a transport control systems (SAP) via RESTful API. This interface allows decision making in resource allocation and furthermore the adaptation of the digital model if the real system changes. Despite the associated challenges in terms of data synchronisation, the integration has benefits such as a reduction in modelling effort and an increase in the lifetime of the digital twin. In the context of this work, the design of the interface between the simulation software and a SAP transport control system via RESTful API is described. Y1 - 2023 SN - 978-3-86360-276-5 U6 - https://doi.org/10.22032/DBT.57813 SP - 281 EP - 291 PB - Universitätsverlag Ilmenau CY - ILmenau ER - TY - PAT A1 - Olbrich, Florian A1 - Pongratz, Christian A1 - Bierl, Rudolf A1 - Ehrlich, Ingo T1 - Method and System for Evaluating a Structural Integrity of an Aerial Vehicle Y1 - 2024 ER - TY - CHAP A1 - Nonn, Aida A1 - Marx, P. T1 - Validated Multiphysics Modeling For Advanced Pipeline Integrity Management T2 - ADIPEC, November 4–7, 2024, Abu Dhabi, UAE N2 - The aim of this paper is to present practical steps for utilizing a validated multiphysics approach for fracture control in CO2 pipelines within the framework of Carbon Capture Transport and Storage (CCTS). Ensuring the arrest of running ductile fracture (RDF) is a crucial safety requirement for the transportation of dense-phase CO2. However, current standards rely on outdated and restrictive methods, imposing severe limitations on pipeline material and structural design. As a result, projects that fall outside these standards face the need for extremely costly tests, often leading to delays or cancellations of CCTS initiatives. This study introduces an advanced, validated, fully-coupled fluid-structure interaction (FSI) model designed to accurately predict fracture propagation in CO2 pipelines. A key advantage of this approach is its use of robust and reproducible calibration and validation procedures combined with high-quality material characterization data. The full coupling of structural, fluid, and backfill models is essential for obtaining precise results, not only in determining arrest occurrence but also in analyzing properties such as fracture velocity history, 3D pressure distributions behind the propagating crack, wall thinning, and crack tip opening angle. The FSI model has demonstrated its value as a cost-effective tool for safety assessments, enabling the development of fracture control plans that specify minimum required material properties and fluid compositions for optimized pipeline design, both onshore and offshore. Additionally, performing virtual studies with the parameterized FSI model enables the generation of synthetic data for training and validating a machine learning surrogate model. This surrogate model can be integrated into industrial practices, facilitating the application of multiphysics modeling without the need for extensive expertise. Y1 - 2024 U6 - https://doi.org/10.2118/222279-MS ER - TY - CHAP A1 - Rill, Georg ED - Apetaur, Milan T1 - Vehicle Dynamics in Real-Time Simulation T2 - The dynamics of vehicles on roads and on tracks N2 - This paper presents some ideas on a new concept, named COMPACT (Computer Simulation of Passenger Cars and Trucks). COMPACT was developed for the mathematical description of vehicles in all driving situations. As COMPACT is completely adopted to the particular problems in road vehicle dynamics, it results in a computer code where execution time is minimized. Thus, even real-time application at the Daimler-Benz driving simulator is possible. Previous Chapter Next Chapter Y1 - 2021 SN - 9781003210894 U6 - https://doi.org/10.1201/9781003210894-40 SP - 337 EP - 347 PB - CRC Press CY - Boca Raton ER - TY - CHAP A1 - Herrmann, David A1 - Schaeffer, Leon A1 - Merker, Lukas A1 - Zentner, Lena A1 - Böhm, Valter ED - Nguyen, Duc-Nam ED - Tran, Ngoc Dang Khoa ED - van Huynh, Tuan ED - Ono, Takahito ED - van Nguyen, Hieu ED - Pandey, Ashok Kumar T1 - An Approach to the Realization of Multistable Tensegrity Structures with Deformable Compressed Members T2 - Microactuators, Microsensors and Micromechanisms : MAMM 2024. N2 - Within this paper a novel tensegrity-mechanism is described. The mechanism is based on a tensegrity principle with multiple states of self-equilibrium. The tensegrity mechanism is built upon a mechanical compliant tensegrity structure, consisting of tensioned and compressed members. The existence of the different states of self-equilibrium depends on the parameters of deformable compressed members with continuous or discontinuous load-displacement characteristic. The working principle of the mechanism and the mechanical compliance is verified by theoretical investigations. Therefore, in the first step, the deformable compressed members are analyzed separately. With the help of the subsequent following form-finding procedure the equilibrium configurations of the mechanism and their static stability are analyzed in dependence of the mechanical parameters of the compressed and tensioned members. As a specific application case, the use of the mechanism as a variable stiffness device is discussed. Y1 - 2025 SN - 978-3-031-83356-4 U6 - https://doi.org/10.1007/978-3-031-83357-1_34 SP - 343 EP - 350 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Deuter, Daniel A1 - Haj, Amer A1 - Brawanski, Alexander A1 - Krenkel, Lars A1 - Schmidt, Nils Ole A1 - Doenitz, Christian T1 - Fast simulation of hemodynamics in intracranial aneurysms for clinical use JF - Acta Neurochirurgica N2 - BACKGROUND: A widely accepted tool to assess hemodynamics, one of the most important factors in aneurysm pathophysiology, is Computational Fluid Dynamics (CFD). As current workflows are still time consuming and difficult to operate, CFD is not yet a standard tool in the clinical setting. There it could provide valuable information on aneurysm treatment, especially regarding local risks of rupture, which might help to optimize the individualized strategy of neurosurgical dissection during microsurgical aneurysm clipping. METHOD: We established and validated a semi-automated workflow using 3D rotational angiographies of 24 intracranial aneurysms from patients having received aneurysm treatment at our centre. Reconstruction of vessel geometry and generation of volume meshes was performed using AMIRA 6.2.0 and ICEM 17.1. For solving ANSYS CFX was used. For validational checks, tests regarding the volumetric impact of smoothing operations, the impact of mesh sizes on the results (grid convergence), geometric mesh quality and time tests for the time needed to perform the workflow were conducted in subgroups. RESULTS: Most of the steps of the workflow were performed directly on the 3D images requiring no programming experience. The workflow led to final CFD results in a mean time of 22 min 51.4 s (95%-CI 20 min 51.562 s-24 min 51.238 s, n = 5). Volume of the geometries after pre-processing was in mean 4.46% higher than before in the analysed subgroup (95%-CI 3.43-5.50%). Regarding mesh sizes, mean relative aberrations of 2.30% (95%-CI 1.51-3.09%) were found for surface meshes and between 1.40% (95%-CI 1.07-1.72%) and 2.61% (95%-CI 1.93-3.29%) for volume meshes. Acceptable geometric mesh quality of volume meshes was found. CONCLUSIONS: We developed a semi-automated workflow for aneurysm CFD to benefit from hemodynamic data in the clinical setting. The ease of handling opens the workflow to clinicians untrained in programming. As previous studies have found that the distribution of hemodynamic parameters correlates with thin-walled aneurysm areas susceptible to rupture, these data might be beneficial for the operating neurosurgeon during aneurysm surgery, even in acute cases. Y1 - 2025 U6 - https://doi.org/10.1007/s00701-025-06469-9 VL - 167 PB - Springer ER - TY - CHAP A1 - Rütten, Markus A1 - Krenkel, Lars A1 - Quadrio, Maurizio T1 - Simulation and Analyis of the Unsteady Flow within Nasal Airways T2 - 9th European Congress on Computational Methods in Applied Sciences and Engineering - ECCOMAS Congress, 3-7 June 2024, Lisbon, Portugal Y1 - 2024 UR - https://re.public.polimi.it/handle/11311/1269952 ER - TY - JOUR A1 - Gebhardt, Jakob A1 - Schlamp, Matthias A1 - Ehrlich, Ingo A1 - Hiermaier, Stefan T1 - Low-velocity impact behavior of elliptic curved composite structures JF - International Journal of Impact Engineering N2 - Although many composite structures are inconsistently curved, such as the leading edges of aircraft wings, the variety of research in impact engineering is almost limited to the impact performance of plates or cylindrically curved specimens. It is not known whether the findings obtained from standardized tests can be transferred to curved structures or which adaptions are required. Therefore, a deeper understanding of the deformation and damage behavior of inconsistently curved structures is essential to transfer the observed impact behavior of flat specimens to general curved structures and therefore to utilize the full lightweight potential of a load-specific design. An accurate description of the procedure as well as the results of the experimental and numerical study of the low-velocity impact behavior of differently single-curved elliptic specimens is presented. To close the research gap of the impact behavior of geometries with curvatures between the plates and simplified leading edges, novel specimens geometries have been derived from established impact test standards. Glassfiber-reinforced specimens are subjected to an instrumented impact test at constant impact energy. This is numerically investigated by a stacked-layer model, which used cohesive zone modeling to enable the simulation of matrix cracking, fiber fracture and delamination. The resulting projected damage areas, as well as the force and deflection histories, were evaluated and section cuts were examined to discuss the damage morphology, formation and propagation process. Significant effects on maximum deflection, compliance and dynamic behavior on the size and morphology of damage were found. KW - Impact damage KW - Impact behavior KW - Curved composite KW - Numerical model KW - GFRP Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-59304 N1 - Corrsponding author: Jakob Gebhardt VL - 180 PB - Elsevier ER - TY - JOUR A1 - Schulz, Carsten A1 - Vogl, Yannick A1 - Geiger, Benjamin A1 - Schaeffer, Thomas T1 - Vor- und Nachteile einer Lumped-Mass-Modellierung von Förderbändern am Beispiel eines Zwei-Walzensystems JF - Forschung im Ingenieurwesen JF - Engineering Research N2 - Im Betrieb von Förderbändern auftretende Phänomene sind das Bandwandern in Achsrichtung der Walzen und die Bandverformung in der Bandebene [1, S. 142]. Das Bandwandern ist bisher detailliert untersucht [2–4], während die Bandverformung Gegenstand weniger Veröffentlichungen ist. Deshalb wird in diesem Artikel eine Methode zur Berechnung der sich im dynamischen Betrieb einstellenden Verformung eines elastischen Förderbandes vorgestellt. Dazu wird ein Mehrkörpersimulations-Modell basierend auf der Lumped-Mass-Modellierung verwendet. Als Untersuchungsbeispiel dient ein Zwei-Walzensystem mit flexiblen und zylindrischen Walzen, sowie ein flexibles Förderband. Es zeigt sich, dass mit der Lumped-Mass-Modellierung eine dynamische Bandverformung, die von der gewählten Diskretisierung abhängt, berechnet werden kann. Aufgrund dieser Abhängigkeit ist es notwendig eine Konvergenzanalyse durchzuführen. Zusätzlich ist darauf zu achten, dass die künstliche Anregung aufgrund der Lumped-Mass-Modellierung nicht mit einer Eigenfrequenz des Modells zusammenfällt. N2 - Phenomena occurring in the operation of conveyor belts are belt walking in the axial direction of the rollers and belt deformation in the belt plane [1, S. 142]. Whereas [2,3,4] investigate the first effect in detail [2,3,4], the latter is mostly neglected. The authors therefore focus on the calculation of the deformation of the elastic conveyor belt during dynamic operation using a flexible multibody approach. To consider the flexibility of the belt in an efficient way, the model uses the well-known Lumped-Mass-Approach. The discretization of the model (number and distance of masses) thereby impacts the shape of the band deformation. The article investigates the minimum required discretization for two dimensions, the effect on the system response and the influence on the computation time. As an example, a two-roller system with flexible, cylindrical rolls and a flexible conveyor belt is used. The results of the model will be compared with theoretical expectations and show very promising results. T2 - Pros and cons of Lumped Mass Modelling of conveyor belts using a two-roller system Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-72891 SN - 0015-7899 N1 - Corresponding author der OTH Regensburg: Carsten Schulz VL - 88 IS - 1 PB - Springer Vieweg CY - Belrin ; Heidelberg ER - TY - GEN A1 - Saffert, Anne-Sophie A1 - Melzner, Maximilian A1 - Dendorfer, Sebastian T1 - Biomechanical Analysis of the Right Elevated Glenohumeral Joint in Violinists during Legato-Playing T2 - Biomdlore 2021: 21-23 October 2021 Vilnius/Trakai, Lithuania N2 - BACKGROUND: Many statistics reveal that violin players suffer most often from musculoskeletal disorders compared to musicians of other instrument groups. A common phenomenon, especially observed in violin beginners, is the tendency to elevate the right shoulder during playing the violin. This can probably lead to serious disorders in long-term practice with repetitive movements. OBJECTIVE: For this reason, this study investigated the relationship between the right shoulder elevation and the force in the right glenohumeral joint during violin playing. It was hypothesized that the forces in the right glenohumeral joint are higher during playing with the right shoulder raised compared to playing in normal posture. METHODS: Motion capture data from four experienced violinists was recorded and processed by means of musculoskeletal simulation to get the force and elevation angle while playing with raised shoulder and in normal position. RESULTS: The results indicate that the absolute values of the resulting force, as well as the forces in the mediolateral, inferosuperior, and anteroposterior directions, are higher in playing the violin with the shoulder raised than in a normal posture. CONCLUSIONS: Elevating the right shoulder while playing the violin may pose a potential problem. Y1 - 2021 U6 - https://doi.org/10.3233/THC-219001 N1 - Veröffentlicht in: Technology and Health Care, vol. 30, no. 1 (Selected Papers From the 13th International Conference BIOMDLORE 2021), pp. 177-186, 2022 ER - TY - GEN A1 - Herrmann, David A1 - Schaeffer, Leon A1 - Schmitt, Lukas A1 - Körber, Wolfgang A1 - Merker, Lukas A1 - Zentner, Lena A1 - Böhm, Valter T1 - Design, Erprobung und Vergleich von zwei Manipulatoren auf Basis von nachgiebigen Tensegrity-Strukturen T2 - 10. IFToMM D-A-CH Konferenz 2024: 05./06. März 2024, Universität Rostock N2 - Kurzfassung des Tagungsbeitrags. T2 - Design, test and comparison of two manipulators based on compliant tensegrity-structures Y1 - 2024 UR - https://nbn-resolving.org/urn:nbn:de:hbz:465-20240304-095947-9 U6 - https://doi.org/10.17185/duepublico/81587 ER - TY - JOUR A1 - Kheiroddin, Parastoo A1 - Schöberl, Patricia A1 - Althammer, Michael A1 - Cibali, Ezgi A1 - Würfel, Thea A1 - Wein, Hannah A1 - Kulawik, Birgit A1 - Buntrock-Döpke, Heike A1 - Weigl, Eva A1 - Gran, Silvia A1 - Gründl, Magdalena A1 - Langguth, Jana A1 - Lampl, Benedikt A1 - Judex, Guido A1 - Niggel, Jakob A1 - Pagel, Philipp A1 - Schratzenstaller, Thomas A1 - Schneider-Brachert, Wulf A1 - Gastiger, Susanne A1 - Bodenschatz, Mona A1 - Konrad, Maike A1 - Levchuk, Artem A1 - Roth, Cornelius A1 - Schöner, David A1 - Schneebauer, Florian A1 - Rohrmanstorfer, René A1 - Burkovski, Andreas A1 - Ambrosch, Andreas A1 - Wagner, Thomas A1 - Kabesch, Michael ED - Buonsenso, Danilo T1 - Results of WICOVIR Gargle Pool PCR Testing in German Schools Based on the First 100,000 Tests JF - Frontiers in Pediatrics N2 - Background: Opening schools and keeping children safe from SARS-CoV-2 infections at the same time is urgently needed to protect children from direct and indirect consequences of the COVID-19 pandemic. To achieve this goal, a safe, efficient, and cost-effective SARS-CoV-2 testing system for schools in addition to standard hygiene measures is necessary. Methods: We implemented the screening WICOVIR concept for schools in the southeast of Germany, which is based on gargling at home, pooling of samples in schools, and assessment of SARS-CoV-2 by pool rRT-PCR, performed decentralized in numerous participating laboratories. Depooling was performed if pools were positive, and results were transmitted with software specifically developed for the project within a day. Here, we report the results after the first 13 weeks in the project. Findings: We developed and implemented the proof-of-concept test system within a pilot phase of 7 weeks based on almost 17,000 participants. After 6 weeks in the main phase of the project, we performed >100,000 tests in total, analyzed in 7,896 pools, identifying 19 cases in >100 participating schools. On average, positive children showed an individual CT value of 31 when identified in the pools. Up to 30 samples were pooled (mean 13) in general, based on school classes and attached school staff. All three participating laboratories detected positive samples reliably with their previously established rRT-PCR standard protocols. When self-administered antigen tests were performed concomitantly in positive cases, only one of these eight tests was positive, and when antigen tests performed after positive pool rRT-PCR results were already known were included, 3 out of 11 truly positive tests were also identified by antigen testing. After 3 weeks of repetitive WICOVIR testing twice weekly, the detection rate of positive children in that cohort decreased significantly from 0.042 to 0.012 (p = 0.008). Interpretation: Repeated gargle pool rRT-PCR testing can be implemented quickly in schools. It is an effective, valid, and well-received test system for schools, superior to antigen tests in sensitivity, acceptance, and costs. KW - children KW - COVID-19 KW - Germany KW - PCR KW - pooling KW - gargle KW - schools KW - pandemic KW - Covid-19 KW - Polymerase-Kettenreaktion KW - Nachweis KW - Schulkind KW - Deutschland Y1 - 2021 U6 - https://doi.org/10.3389/fped.2021.721518 SN - 2296-2360 VL - 9 PB - frontiers ER - TY - JOUR A1 - Becker, Tatiana I. A1 - Böhm, Valter A1 - Schale, Florian A1 - Zimmermann, Klaus T1 - Vibrating sensor unit made of a magnetoactive elastomer with field-adjustable characteristics JF - Journal of Magnetism and Magnetic Materials N2 - The present work deals with the investigation of the oscillatory behavior displayed by a vibrating sensor unit made of a magnetoactive elastomer (MAE). Since this type of smart materials consists of an elastic matrix and micro-magnetic particles, it reveals exceptional magnetic-field-dependent material properties. The forced vibration response under the bending of the MAE unit subjected to in-plane harmonic kinematic excitation of the housing is studied. It is found that the amplitude-frequency characteristics of the MAE unit can be changed considerably by means of an external homogeneous magnetic field. With and without applied field, the unit displays different steady-state responses for the same excitation, and the resonance occurs at various ranges of the excitation frequency. The nonlinear phenomenon of the resonance hysteresis is observed depending on whether the excitation frequency increases or decreases. It is shown that the MAE vibrations can be detected based on the magnetic field distortion measurements. The presented prototype of the MAE-based vibrating unit with field-adjustable “configuration” can be potentially implemented for realization of acceleration sensor systems with adaptive sensitivity. Y1 - 2020 U6 - https://doi.org/10.1016/j.jmmm.2019.166196 VL - 498 IS - March PB - Elsevier ER - TY - BOOK A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Borchsenius, Fredrik T1 - Grundlagen und computergerechte Methodik der Mehrkörpersimulation N2 - Dieses Lehrbuch stellt die Methoden der Mehrkörpersimulation anschaulich dar und erläutert an einfachen Beispielen die Vor- und Nachteile bei der praktischen Anwendung. In den Text integrierte Matlab-Skripte und -Funktionen verdeutlichen die einzelnen Methoden. Die Modellbildung, die mathematische Beschreibung und die numerische Simulation von Systemen starrer Körper bilden dabei die Schwerpunkte. Konkrete Beispiele beinhalten einen Bungee-Sprung, die Eigendynamik eines Traktors mit Vorderachsfederung, das Hubschrauberrotorblatt sowie eine Pkw-Vorderachse. Die Lösungen zu den Übungsaufgaben und die im Text integrierten Matlab-Beispiele, die zum Teil durch Animationen angereichert sind, sowie zusätzliche Beispiele und Anwendungen stehen auf der Verlagshomepage beim Buch zum Download zur Verfügung und ermöglichen dadurch auch ein effizientes Selbststudium. Y1 - 2020 SN - 978-3-658-28911-9 U6 - https://doi.org/10.1007/978-3-658-28912-6 PB - Springer Fachmedien CY - Wiesbaden ET - 4. Aufl. ER - TY - CHAP A1 - Mühlbauer, Christian A1 - Rabl, Hans-Peter A1 - Rottengruber, Hermann ED - Siebenpfeiffer, Wolfgang T1 - Development of a Methodology for Acoustic Analysis and Optimization of Mechatronic Fuel Injection Systems T2 - Automotive Acoustics Conference 2019: Proceedings, 5. Internationale ATZ-Fachtagung Fahrzeugakustik N2 - To identify the sound quality of fuel injection systems as a frontloading measure, a system test bench has been developed that simulates the structure and airborne noise emission. The setup of the system test bench includes an assembly of the acoustical relevant engine parts and an encapsulated drive for the high-pressure pump. A specific control unit enables a high variability for the operation strategy of the injection system. The focus of this study is on the development of a methodology to analyze and optimize the sound quality of gasoline direct injectors in critical operation points by suitable active means. For this, the injection parameters in engine idle have been identified and subsequently transferred to the system test bench. Additionally, the injection parameters have been optimized acoustically and the impacts on the key functions regarding injection rating and shot-to-shot scattering of the injected fuel mass are discussed. Y1 - 2020 SN - 978-3-658-27668-3 U6 - https://doi.org/10.1007/978-3-658-27669-0_15 SP - 211 EP - 225 PB - Springer Vieweg CY - Wiesbaden ER - TY - GEN A1 - Schimmer, Florian A1 - Gebhardt, Jakob A1 - Motsch-Eichmann, N. A1 - Hausmann, Joachim M. A1 - Ehrlich, Ingo T1 - The effect of curvature on the low-velocity impact resistance of CF/PEEK laminates T2 - 30 Years IVW Anniversary Colloquium, Leibnitz-Institut für Verbundwerkstoffe Kaiserslautern, 2021 Y1 - 2021 ER - TY - JOUR A1 - Stichel, T. A1 - Raths, Max A1 - Laumer, Tobias A1 - Roth, Stephan T1 - Multi-Material Deposition of Polymer Powders with Vibrating Nozzles for a New Approach of Laser Sintering JF - Journal of Laser Micro/Nanoengineering (JLMN) N2 - Conventional Selective Laser Sintering of polymers is restricted to the processing of single materials. The fabrication of components consisting of different material regions is a challenge which cannot be realized by standard coating devices basing on blades or rollers. Thus, advanced coating and deposition techniques are needed which enable the precise and reliable control over very small powder quantities in order to prepare arbitrary powder patterns with high accuracy and repeatability. In this report, the delivery of polymer powder by vibrating nozzles inside laser sintering machines is investigated. Therefore, a steel nozzle attached to a piezo actuator is integrated into a machine, whereas the nozzle itself features internal channels which allow the precise control over the powder temperature using heat transfer oil. The setup is used to study the influence of different system configurations on the powder deposition characteristics as resolution and layer surface roughness. The results show that temperature influences the mass flow depending on the material used and that a precise deposition of powder pattern with microscale resolution is possible with optimized parameters. Finally, the multimaterial powder pattern is fused by a new illumination strategy of laser sintering which is called Simultaneous Intensity-Selective Laser Sintering in order to demonstrate the potential of this new approach. Y1 - 2018 U6 - https://doi.org/10.2961/jlmn.2018.02.0002 VL - 13 IS - 2 SP - 55 EP - 62 PB - JLPS-Japan Laser Processing Society ER - TY - CHAP A1 - Laumer, Tobias A1 - Stichel, T. A1 - Sachs, Marius A1 - Amend, Philipp A1 - Schmidt, Michael ED - Bártolo, Paulo T1 - Qualification and modification of new polymer powders for laser beam melting using Ulbricht spheres T2 - High value manufacturing : Advanced research in virtual and rapid prototyping ; Proceedings of the 6th International Conference on Advanced Research and Rapid Prototyping, Leiraia, Portugal, 1-5 October, 2013 N2 - The restricted amount of available materials for Laser Beam Melting (LBM) of polymers is one of the main limitations for expanding the technology. Current qualification methods deal with problems like inadequate powder flowability or high part porosities among others but do not offer a detailed analysis of the important beam-matter-interaction between powder particles and electro-magnetic laser radiation. In this paper, polyethylene powder is qualified for the LBM process and specifically analyzed regarding the optical material properties of the powder for a wavelength of 10.6 μm. By admixing graphite as absorption intensifier the change of the optical material properties and the thereby connected processing parameters are analyzed. Furthermore an explanation approach is given to explain the relation between different transmittances of different powder particles and the optical material properties of the polymer powders. Y1 - 2014 UR - https://www.researchgate.net/publication/286311000_Qualification_and_modification_of_new_polymer_powders_for_laser_beam_melting_using_Ulbricht_spheres SN - 978-1-138-00137-4 SN - 1138001376 SP - 255 EP - 260 PB - CRC Press CY - Boca Raton ER - TY - BOOK A1 - Rill, Georg A1 - Schaeffer, Thomas T1 - Grundlagen und Methodik der Mehrkörpersimulation N2 - Dieses Lehrbuch stellt die Methoden der Mehrkörpersimulation anschaulich dar und erläutert an einfachen Beispielen die Vor- und Nachteile bei der praktischen Anwendung. In den Text integrierte Matlab-Skripte und -Funktionen verdeutlichen die einzelnen Methoden. Die Modellbildung, die mathematische Beschreibung und die numerische Simulation von Systemen starrer Körper bilden dabei die Schwerpunkte. Konkrete Beispiele beinhalten die Eigendynamik eines Traktors mit Vorderachsfederung, das Hubschrauberrotorblatt sowie eine Pkw- Vorderachse. Die entsprechenden Matlab-Skripte und Lösungen zu den Übungsaufgaben können auf der Springer-Homepage beim Buch heruntergeladen werden. Neu aufgenommen wurden SparseMatrix Operationen sowie ein Beispiel zu einfach geschlossenen kinematischen Schleifen. Y1 - 2017 SN - 978-3-658-16008-1 U6 - https://doi.org/10.1007/978-3-658-16009-8 PB - Springer CY - Wiesbaden ET - 3. Aufl. ER - TY - BOOK A1 - Rill, Georg A1 - Schaeffer, Thomas T1 - Grundlagen und Methodik der Mehrkörpersimulation : Vertieft in Matlab-Beispielen, Übungen und Anwendungen N2 - Dieses Lehrbuch vermittelt nicht nur Grundlagen, sondern stellt auch die Methoden der Mehrkörpersimulation anschaulich dar und erläutert an einfachen Beispielen die Vor- und Nachteile bei der praktischen Anwendung. In den Text integrierte Matlab-Skripte und -Funktionen verdeutlichen die einzelnen Methoden und ermöglichen es, Aufwand und Problematik bei der Umsetzung der Theorie innerhalb von Simulationsprogrammen einzuschätzen. Die Modellbildung, die mathematische Beschreibung und die numerische Simulation von Systemen starrer Körper bilden dabei die Schwerpunkte. Konkret behandelte Beispiele sind die Eigendynamik eines Traktors mit gefederter Vorderachse, das Rotorblatt eines Hubschraubers sowie die Vorderachse eines Pkws. Die entsprechenden Matlab-Skripte und Lösungen zu den Übungsaufgaben können auf der Springer-Homepage beim Buch heruntergeladen werden. Der Inhalt Dynamik des starren Körpers - Bewegungsgleichungen - Starre Körper mit elastischen und kinematischen Verbindungselementen - Integrationsverfahren - Rekursiver Algorithmus - Differential-Algebraische Gleichungen - Analyse von Mehrkörpersystemen - Anwendungs- und Übungsbeispiele aus der Technik Die Zielgruppen Studenten des Maschinenbaus, der Elektrotechnik und Mechatronik sowie der Biomechanik an Hochschulen und Universitäten Ingenieure in der Praxis, die sich mit Fragestellungen der Mehrkörpersimulation (MKS) befassen Entwickler aus der Kfz-Technik sowie Fachleute aus F+E Die Autoren Dr.-Ing. Georg Rill ist Professor mit den Lehrgebieten Technische Mechanik, Ingenieurinformatik, Fahrdynamik, Mehrkörperdynamik sowie Laborleiter Fahrdynamik. Dr.-Ing. Thomas Schaeffer ist Professor mit den Lehrgebieten Konstruktion, CAD, Maschinenelemente und Getriebetechnik, Mehrkörpersysteme und Bewegungstechnik sowie Laborleiter Mehrkörpersimulation, beide an der Ostbayerischen Technischen Hochschule (OTH) Regensburg. Y1 - 2014 U6 - https://doi.org/10.1007/978-3-658-06084-8 PB - Springer CY - Berlin ER - TY - BOOK A1 - Fricke, Andreas A1 - Günzel, Detlef A1 - Schaeffer, Thomas T1 - Bewegungstechnik BT - Konzipieren und Auslegen von mechanischen Getrieben N2 - Das optimale Bewegungssystem - Probleme der Bewegungstechnik systematisch und praxisorientiert lösen! Ein umfassender Überblick über alle wesentlichen Arbeitsschritte zum Lösen von Bewegungsaufgaben, die zu den alltäglichen Problemstellungen eines Produktentwicklers gehören. Das Konzipieren und Konstruieren von Bewegungssystemen von Maschinen, Geräten und Vorrichtungen, in denen Arbeitsorgane, Werkzeuge, Werkstücke oder Verarbeitungsgut bestimmte Bewegungen auszuführen haben, prägt entscheidend das Gesamtverhalten der Maschine. Aus diesem Grund ist eine systematische, moderne und vor allem praxisorientierte Lösung dieser Aufgaben von großer Bedeutung für den Produktentwickler. Das Lehrbuch bespricht alle dafür wesentlichen Themenbereiche und vermittelt die jeweiligen Arbeitsschritte in anschaulicher Weise beispielhaft und praxisnah unter Nutzung allgemeingültiger, effektiver Methoden und Verfahren. Dabei richtet sich das Buch sowohl an Studierende technischer Studiengänge als auch an Praktiker, Techniker und Ingenieure aus der Industrie. Diverse Beispiele und Übungsaufgaben zum Selbststudium unterstützen dabei den Lernprozess und das Verständnis der Thematik. KW - Getriebelehre Y1 - 2022 SN - 978-3-446-46859-7 U6 - https://doi.org/10.3139/9783446468597 PB - Hanser CY - München ET - 3., aktualisierte Auflage ER - TY - GEN A1 - Chavez Vega, Jhohan Harvey A1 - Böhm, Valter A1 - Scharff, Moritz A1 - Prem, Nina A1 - Monkman, Gareth J. A1 - Becker, Tatiana I. A1 - Günther, L. A1 - Alencastre, Jorge H. A1 - Grieseler, R. A1 - Zimmermann, Klaus T1 - Magneto-active elastomer as viscoelastic foundation material for artificial tactile sensors with tuneable properties T2 - Book of Abstracts of the 16th German Ferrofluid Workshop, Braunschweig, 18.-20.07.2018 Y1 - 2018 SP - 16 EP - 17 ER - TY - JOUR A1 - Schuderer, Matthias A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Schulz, Carsten T1 - Friction modeling from a practical point of view JF - Multibody System Dynamics N2 - AbstractRegularized static friction models have been used successfully for many years. However, they are unable to maintain static friction in detail. For this reason, dynamic friction models have been developed and published in the literature. However, commercial multibody simulation packages such as Adams, RecurDyn, and Simpack have developed their own specific stick-slip models instead of adopting one of the public domain approaches. This article introduces the fundamentals of these commercial models and their behavior from a practical point of view. The stick-slip models were applied to a simple test model and a more sophisticated model of a festoon cable system using their standard parameters. KW - Multibody dynamics KW - Friction KW - Stick-slip effect KW - Adams KW - RecurDyn KW - Simpack Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-72513 SN - 1384-5640 N1 - Corresponding author: Matthias Schuderer PB - Springernature ER - TY - GEN A1 - Schuderer, Matthias A1 - Rill, Georg A1 - Schulz, Carsten A1 - Schaeffer, Thomas T1 - Influence of fictitious bristle parameters in dynamic friction models T2 - Global Annual Meet on Mechanical and Aerospace Engineering (GAMMAE2025), March 10-12, 2025, Rome, Italy N2 - In this study, the influence of bristle parameters in dynamic friction models is investigated, in particular in the LuGre and FrD2 models. These models contain internal states to better capture the friction behavior. The FrD2 model, a second-order dynamic friction model, aims at higher accuracy. The investigation focuses on how the independent variation of the bristle stiffness and the damping parameters affects the model behavior, especially considering the practical approximations used in determining the damping coefficient. Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-80348 ER - TY - BOOK A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Borchsenius, Fredrik T1 - Grundlagen und computergerechte Methodik der Mehrkörpersimulation BT - Vertieft in Matlab-Beispielen, Übungen und Anwendungen N2 - Dieses Lehr- und Übungsbuch vermittelt auf anschauliche Weise die Methoden der Mehrkörpersimulation und verdeutlicht deren Vor- und Nachteile bei der praktischen Anwendung anhand konkreter Beispiele. Die einzelnen Methoden werden durch Matlab-Skripte und -Funktionen verdeutlicht, wobei die Modellbildung, die mathematische Beschreibung und die numerische Simulation von Systemen starrer Körper die Schwerpunkte bilden. Die vorliegende Auflage wurde unter anderem um Matlab-Live-Skripte erweitert, welche kleine Animationen zur Veranschaulichung der Dynamik der Probleme enthalten. Die Lösungen zu den Übungsbeispielen und die integrierten Matlab-Skripte sowie weitere Beispiele und Anwendungen stehen über QR-Codes zum Download zur Verfügung und ermöglichen dadurch auch ein effizientes Selbststudium. KW - ADAMS-Modell KW - McPherson-Achse KW - Euler-Parameter KW - Bushings KW - Kontaktelement KW - Kinematische Bindung KW - Räumliches Doppelpendel KW - Analyse MKS KW - Lumped Mass Modelle KW - SIMPACK-Modell KW - Sparse Matrix KW - Mehrkörpersystem KW - MATLAB KW - Dynamik KW - Simulation Y1 - 2023 U6 - https://doi.org/10.1007/978-3-658-41968-4 PB - Springer Nature ER - TY - CHAP A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Borchsenius, Fredrik T1 - Analyse von Mehrkörpersystemen T2 - Grundlagen und computergerechte Methodik der Mehrkörpersimulation N2 - Nach dem Aufbau eines Mehrkörper-Simulationsmodells muss dieses auf Richtigkeit, Funktionalität und Wirtschaftlichkeit getestet werden. Die Ermittlung der Gleichgewichtslage stellt dabei eine erste Plausibilitäts-Kontrolle dar. Eine Linearisierung mit anschließender Analyse der Eigendynamik liefert Aussagen über die Frequenzen und das Dämpfungsverhalten des Modells. Einfache Erregersignale ermöglichen einen ersten Einblick in das nichtlineare dynamische Verhalten des Modells. Modell-Parameter, die nicht genau bekannt sind, können durch gezielte Variationen plausibel geschätzt oder über eine Optimierung sogar mit optimalen Werten belegt werden. Nach all diesen Tests steht das Mehrkörper- Simulationsmodell dann für praktischeUntersuchungen zurVerfügung, die neben reinen Zeitsimulationen auch Methoden der Inversen Kinematik und der Inversen Dynamik mit einschließen. KW - Gleichgewicht KW - Linearisierung KW - Eigendynamik KW - Fremderregung KW - Optimierung KW - Inverse Kinematik KW - Inverse Dynamik Y1 - 2023 U6 - https://doi.org/10.1007/978-3-658-41968-4_5 SP - 198 PB - Springer ER - TY - CHAP A1 - Schulz, Carsten A1 - Vogl, Yannick A1 - Geiger, Benjamin A1 - Schaeffer, Thomas T1 - Lumped-Mass-Modellierung von Förderbändern am Beispiel eines Zwei-Walzensystems mit flexiblen Walzen T2 - Dresdner Maschinenelemente Kolloquium - DMK 2024, 14.-15. Mai 2024, Dresden Y1 - 2024 ER - TY - JOUR A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Schuderer, Matthias T1 - LuGre or not LuGre JF - Multibody System Dynamics N2 - The LuGre model is widely used in the analysis and control of systems with friction. Recently, it has even been made available in the commercial multibody dynamics simulation software system Adams. However, the LuGre model exhibits well-known drawbacks like too low and force rate-dependent break-away forces, drift problems during sticking periods, and significant differences in non-stationary situations between the pre-defined friction law and the one produced by the LuGre model. In the present literature, these problems are supposed to come from the model dynamics or its nonlinear nature. However, most of these drawbacks are not simple side effects of a dynamic friction model but are caused in the LuGre approach, as shown here, by a too simple and inconsistent model of the bristle dynamics. Standard examples and a more practical application demonstrate that the LuGre model is not a “what you see is what you get” approach. A dynamic friction model with accurate bristle dynamics and consistent friction force is set up here. It provides insight into the physical basis of the LuGre model dynamics. However, it results in a nonlinear and implicit differential equation, whose solution will not be easy because of the ambiguity of the friction characteristics. The standard workaround, a static model based on simple regularized characteristics, produces reliable and generally satisfactory results but definitely cannot maintain a stick. The paper presents a second-order dynamic friction model, which may serve as an alternative. It can maintain a stick and produces realistic and reliable results. KW - Dynamic friction model KW - LuGre model KW - Asymmetric regularization KW - Break-away force KW - Stick-slip KW - Multibody dynamics Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-65653 N1 - Corresponding author: Georg Rill PB - Springer ER - TY - CHAP A1 - Krenkel, Lars A1 - Wagner, Claus A1 - Wolf, Ursula A1 - Scholz, Alexander-Wigbert K. A1 - Terekhov, Maxim A1 - Rivoire, Julien A1 - Schreiber, W. ED - Hirschel, Ernst Heinrich ED - Schröder, Wolfgang ED - Fujii, Kozo ED - Haase, Werner ED - Leer, Bram ED - Leschziner, Michael A. ED - Pandolfi, Maurizio ED - Periaux, Jacques ED - Rizzi, Arthur ED - Roux, Bernard ED - Shokin, Yurii I. ED - Dillmann, Andreas ED - Heller, Gerd ED - Klaas, Michael ED - Kreplin, Hans-Peter ED - Nitsche, Wolfgang T1 - Protective Artificial Lung Ventilation: Impact of an Endotracheal Tube on the Flow in a Generic Trachea T2 - New Results in Numerical and Experimental Fluid Mechanics VII : Contributions to the 16th STAB/DGLR Symposium Aachen, Germany 2008 N2 - Computational Fluid Dynamics (CFD) and experimental investigations on a generic model of the trachea have been carried out focusing on the impact of an endotracheal tube (ETT) on the resulting flow regime. It could be shown that detailed modelling of the airway management devices is essential for proper flow prediction, but secondary details as Murphy Eyes can be neglected. Models with bending and connector promote the formation of stronger secondary flows and disturbances which persist for a longer time. KW - computational fluid dynamics KW - Computational Fluid Dynamics Simulation KW - Endotracheal Tube KW - Particle Image Velocimetry KW - Turbulent Kinetic Energy Y1 - 2010 SN - 978-3-642-14242-0 U6 - https://doi.org/10.1007/978-3-642-14243-7_62 SP - 505 EP - 512 PB - Springer Berlin Heidelberg CY - Berlin, Heidelberg ER - TY - INPR A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Schuderer, Matthias T1 - LuGre or not LuGre N2 - The LuGre model is widely used in the analysis and control of systems with friction. Recently, it has even been made available in the commercial multibody dynamics simulation software system Adams. However, the LuGre model exhibits well-known drawbacks like, too low and force rate dependent break-away forces, drift problems during sticking periods, and significant differences in non-stationary situations between the pre-defined friction law and the one produced by the LuGre model. In the present literature, these problems are supposed to come from the model dynamics or its nonlinear nature. However, most of these drawbacks are not simple side effects of a dynamic friction model but are caused in the LuGre approach, as shown here, by a too simple and inconsistent model of the bristle dynamics. Standard examples and a more practical application demonstrate, that the LuGre model is not a “what you see is what you get” approach. A dynamic friction model with accurate bristle dynamics and consistent friction force is set up here. It provides insight into the physical basis of the LuGre model dynamics. However, it results in a nonlinear and implicit differential equation, whose solution will not be easy because of the ambiguity of the friction characteristics. The standard workaround, a static model based on a simple regularized characteristics, produces reliable and generally satisfactory results, but definitely cannot maintain stick. The paper presents a second order dynamic friction model, which may serve as an alternative. It can maintain stick and produces realistic and reliable results. Y1 - 2022 U6 - https://doi.org/10.21203/rs.3.rs-2266522/v1 ER - TY - GEN A1 - Schuderer, Matthias A1 - Rill, Georg A1 - Schulz, Carsten A1 - Schaeffer, Thomas T1 - Dynamic Stick-Slip Models based on Continuous and Discontinuous Friction Characteristics T2 - ENOC - European Nonlinear Dynamics Conference, 11th, 2024, Delft N2 - This paper presents the implementation of a recently developed continuous second-order dynamic friction model (FrD2) in the commercial multibody system software Simpack, where it is evaluated against Simpack's discontinuous friction model for stick-slip applications in terms of performance. A method for adapting parameters from the well-known LuGre model to the FrD2 model is introduced. The FrD2 model accurately captures complex friction phenomena, including the Stribeck effect, which is essential for simulating friction-induced vibrations. Tested on a festoon cable system and a belt model, the FrD2 model demonstrates itself as a robust alternative to both the LuGre and Simpack models, especially for applications requiring continuous transitions between static and dynamic friction states, long-term stiction effects, and other complex friction behaviors. KW - Multibody Simulation KW - Simpack KW - FrD2 KW - LuGre KW - Stick-slip Y1 - 2024 U6 - https://doi.org/10.2139/ssrn.5014569 ER - TY - GEN A1 - Friedrich, Janet A1 - Rivoire, Julien A1 - Scholz, Alexander-Wigbert K. A1 - Wiegbert, A1 - Terekov, Maxim A1 - Kbrich, Rainer A1 - Krenkel, Lars A1 - Wagner, Claus A1 - Schreiber, Laura Maria T1 - Exploration of Gas Flow During High Frequency Oscillated Ventilation by 19F-Gas-MRI T2 - Proceedings of the International Society for Magnetic Resonance in Medicine N2 - To detect convective gas flow inside the large airways during high frequency oscillated ventilation (HFOV) the fluorinated contrast gas Heptafluoropropane was used for 19F-MRI. In a first study the comparison between constant flow measurements and Computational Fluid Dynamics (CFD) simulations provided a good agreement. In a following experiment oscillated flow was applied to a lung phantom consisting of ventilation bag and long pipe. The pressure wave inside the pipe was explored point-by-point and corresponding velocities were determined. With these experiments it could be shown for the first time that flow measurement during HFOV using fluorinated contrast gas is feasible. Y1 - 2010 UR - https://archive.ismrm.org/2010/2527.html VL - 18 ER - TY - JOUR A1 - Rill, Georg A1 - Schuderer, Matthias T1 - A Second-Order Dynamic Friction Model Compared to Commercial Stick–Slip Models JF - Modelling N2 - Friction has long been an important issue in multibody dynamics. Static friction models apply appropriate regularization techniques to convert the stick inequality and the non-smooth stick–slip transition of Coulomb’s approach into a continuous and smooth function of the sliding velocity. However, a regularized friction force is not able to maintain long-term stick. That is why dynamic friction models were developed in recent decades. The friction force depends herein not only on the sliding velocity but also on internal states. The probably best-known representative, the LuGre friction model, is based on a fictitious bristle but realizes a too-simple approximation. The recently published second-order dynamic friction model describes the dynamics of a fictitious bristle more accurately. It is based on a regularized friction force characteristic, which is continuous and smooth but can maintain long-term stick due to an appropriate shift in the regularization. Its performance is compared here to stick–slip friction models, developed and launched not long ago by commercial multibody software packages. The results obtained by a virtual friction test-bench and by a more practical festoon cable system are very promising. Thus, the second-order dynamic friction model may serve not only as an alternative to the LuGre model but also to commercial stick–slip models. KW - commercial stick–slip friction models KW - dynamic friction model KW - long-term stick KW - multibody dynamics Y1 - 2023 U6 - https://doi.org/10.3390/modelling4030021 SN - 2673-3951 N1 - Corresponding author: Georg Rill VL - 4 IS - 3 SP - 366 EP - 381 PB - MDPI ER - TY - INPR A1 - Rill, Georg A1 - Schuderer, Matthias T1 - A Second Order Dynamic Friction Model Compared to Commercial Stick-Slip Models N2 - Friction has long been an important issue in multibody dynamics. Static friction models apply appropriate regularization techniques to convert the stick inequality and the non-smooth stick-slip transition of Coulomb’s approach into a continuous and smooth function of the sliding velocity. However, a regularized friction force is not able to maintain long-term stick. That is why, dynamic friction models were developed in the last decades. The friction force depends herein not only on the sliding velocity but also on internal states. The probably best known representative, the LuGre friction model, is based on a fictitious bristle but realizes a too simple approximation. The recently published second order dynamic friction model describes the dynamics of a fictitious bristle more accurately. Its performance is compared here to stick-slip friction models, developed and launched not long ago by commercial multibody software packages. KW - dynamic friction model KW - commercial stick-slip friction models KW - long-term stick KW - multibody dynamics Y1 - 2023 U6 - https://doi.org/10.20944/preprints202306.1233.v1 ER - TY - JOUR A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Schratzenstaller, Thomas A1 - Dendorfer, Sebastian A1 - Böhm, Valter T1 - Theoretical considerations on stiffness characteristics of a 3-dimensional tensegrity joint model for the use in dynamic hand orthoses JF - Journal of Medical Robotics Research Y1 - 2025 U6 - https://doi.org/10.1142/S2424905X25400069 PB - World Scientific ER - TY - GEN A1 - Schuderer, Matthias A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Schulz, Carsten T1 - Friction modeling from a practical point of view T2 - MULTIBODY2023: 11th ECCOMAS Thematic Conference on Multibody Dynamics, Tampa, 24th-28th May 2023 Y1 - 2023 ER - TY - JOUR A1 - Maier, Eva A1 - Zentgraf, Jan A1 - Angele, Eveline A1 - Zorzin, José A1 - Taschner, Michael A1 - Widbiller, Matthias A1 - Galler, Kerstin A1 - Schratzenstaller, Thomas T1 - A re-usable 3D-printed training model for the endodontic management of dental trauma in immature teeth JF - International endodontic journal N2 - AIM: To develop a 3D-printed model enabling treatment simulation of trauma-related endodontic and restorative procedures like revitalization or placement of an apical plug on teeth with incomplete root formation. METHODOLOGY: To generate a realistic training model suitable for trauma-related simulations, CT-Data sets were segmented, combined, adjusted and optimized using computer-aided design features. Specific focus was on optimally reflecting characteristics of immature teeth like open apical foramina and thin root walls. For reflection of the revitalization process, a set-up including a tube filled with red liquid under pressure was developed to be perforated during the procedure by the trainee, simulating bleeding from the apical papilla into the root canal system. Design was based on a combination of cost-effective simple parts combined with 3D-printed components to achieve maximal accessibility, exchangeability and re-usability. Model assembly and preparation were described in step-by-step instructions. RESULTS: As a result of the developmental process, the presented model qualifies for the training of the endodontic management of complications on immature teeth after dental trauma. Step-by-step descriptions aligned with the clinical procedures are performable for a revitalization procedure, for pulpotomy followed by fragment re-attachment and splint application and for placement of an apical plug using hydraulic calcium silicate cements. CONCLUSIONS: The model successfully achieved its intended objectives, so that it may be used in the future in various dental trauma treatment simulations for undergraduate and postgraduate education on the endodontic management of trauma-related therapies in immature teeth. Its common manufacturing process, affordability and re-usability support accessibility and sustainability. Y1 - 2025 U6 - https://doi.org/10.1111/iej.14235 SN - 1365-2591 VL - 2025 PB - Wiley ER - TY - INPR A1 - Schulz, Carsten A1 - Graneß, Henry A1 - Weinzierl, Stefan A1 - Nicklas, Johannes T1 - Eigenvalue perturbation in drivetrain analysis and optimization N2 - The optimization of the dynamic behavior of drive systems often involves targeted modifications of the system characteristics. Structural and parametric modifications are used to satisfy the constraints of the dynamic requirements. However, many optimizations are still achieved by intuition or parameter variations, even though more streamlined and easy-to-implement tools such as the eigenvalue perturbation method are available. In this article, the eigenvalue perturbation method in the form of an eigenvalue sensitivity analysis is used to efficiently optimize the dynamic behavior for two different use cases using different optimization measures. This paper demonstrates, how eigenvalue perturbation theory can efficiently optimize drivetrain dynamics by systematically modifying system parameters. Two case studies show how eigenvalue sensitivity analysis achieves targeted frequency shifts to avoid resonances: (1) adapting shaft stiffness and control parameters in a torsional drivetrain, and (2) optimizing structural modifications in a wind turbine bedplate. The study introduces the eigenvector tensor product as a weighting matrix, identifying key parameters for effective redesign. Compared to conventional parameter studies, this method enables precise control over system dynamics with minimal computational effort, making it highly applicable for vibration mitigation and drivetrain optimization. Y1 - 2025 U6 - https://doi.org/10.21203/rs.3.rs-6368754/v1 PB - Research Square Platform LLC ER - TY - CHAP A1 - Herrmann, David A1 - Kunze, Julian A1 - Kobes, Julian A1 - Seelecke, Stefan A1 - Motzki, Paul A1 - Rizzello, Gianluca A1 - Böhm, Valter T1 - A mobile tensegrity robot driven by rolled dielectric elastomer actuators T2 - 2025 IEEE 8th International Conference on Soft Robotics (RoboSoft), 22-26.April 2025, Lausanne N2 - This paper presents a tensegrity-based mobile robot powered by dielectric elastomer actuators (DEAs), which provide high compliance and adaptability. The design consists of two V-shaped members linked by DEAs, enabling both symmetrical and asymmetrical actuation for varied movement patterns. Modal analysis and simulations show that uniform DEA actuation supports efficient linear motion, while asymmetrical actuation enables controlled circular paths. Experimental testing highlights the influence of voltage waveforms, frequencies, and surface types on speed, with optimal performance achieved using rectangular waveforms on low-friction surfaces. The robot reaches a top speed of 188 mm/s, among the highest reported for DEA-driven robots. KW - Vibrations KW - Surface waves KW - Modal analysis KW - Resonant frequency KW - Soft robotics KW - Mobile robots KW - Rubber KW - Transient analysis KW - Dielectric elastomer actuators KW - Testing Y1 - 2025 U6 - https://doi.org/10.1109/RoboSoft63089.2025.11020974 PB - IEEE ER - TY - CHAP A1 - Schaeffer, Leon A1 - Schmaußer, Theresa A1 - Herrmann, David A1 - Lehmann, Lukas A1 - Dendorfer, Sebastian A1 - Böhm, Valter T1 - Multi-Body Simulation of a Dynamic Hand Orthosis based on a Prestressed Compliant Structure Incorporating the Human Hand T2 - 2025 International Symposium on Medical Robotics (ISMR), May 14-16, 2025, Atlanta, GA, USA, N2 - Many dynamic hand orthoses use one degree of freedom joints, such as hinge joints. Therefore, these orthoses can only partially replicate the complex, multi-axis movement of the hand. A possible solution for this is the use of prestressed compliant structures as the basis for orthoses. Determining the joint forces in the wrist and optimizing the dynamic orthosis to influence these forces as well as acting muscle forces are important steps in the development of these orthoses. For this reason, in this work multi-body simulation models of an orthosis with human hand models are presented. Based on these theoretical investigations, more detailed orthosis models as well as initial prototypes of prestressed compliant dynamic hand orthoses can be developed. KW - Hands KW - Wrist KW - Systematics KW - Simulation KW - Dynamics KW - Refining KW - Prototypes KW - Usability KW - Research and development KW - Testing Y1 - 2025 U6 - https://doi.org/10.1109/ISMR67322.2025.11025982 SP - 80 EP - 86 PB - IEEE ER - TY - JOUR A1 - Vogl, Yannick A1 - Schulz, Carsten A1 - Schaeffer, Thomas A1 - Geiger, Benjamin T1 - Prediction of the wear behavior of a conveyor belt with flexible rollers JF - Multibody System Dynamics N2 - This paper introduces a method to predict wear behavior in conveyor belt systems using a lumped mass modeling approach. While previous research has focused primarily on lateral belt walking, this study shifts attention to belt deformation and its associated wear. Both significantly affect system efficiency and component lifespan. The authors propose using local frictional power as a wear indicator, leveraging its direct relation to frictional work in established wear models. To solely demonstrate the method, the study simulates a conveyor belt with three flexible rollers and a deformable belt modeled through rigid spheres connected by spring-damper elements. The authors visualize frictional power density across the belt width, distinguishing between running and transverse directions. The results demonstrate that the frictional power distribution depends heavily on discretization quality, particularly due to the polygon effect inherent in the lumped mass approach. A convergence analysis reveals the minimum necessary discretization of the belt, ensuring reliable qualitative results. To support the credibility of the work, this study compares theoretical expectations and initial wear observations from a real belt with the results from the shown approach. The plausibility check already shows promising results. The proposed methodology provides an adaptable framework to evaluate wear in belt-like structures. It can be readily adapted to a variety of multibody dynamics applications and integrated into larger MBS models that include the overall drivetrain and engine control. Future work will focus on refining discretization strategies and contact models, as well as validation of the wear model to enable quantitative predictions. Y1 - 2025 U6 - https://doi.org/10.1007/s11044-025-10097-7 SN - 1384-5640 N1 - Die Preprint-Version ist ebenfalls in diesem Repositorium verzeichnet: https://opus4.kobv.de/opus4-oth-regensburg/8194 PB - Springer CY - Cham ER - TY - CHAP A1 - Gersch, Sebastian A1 - Schulz, Carsten A1 - Bagdahn, Jörg T1 - Impact of hatching strategy on mechanical properties and residual stresses in additively manufactured AlSi10Mg components T2 - TMS 2025 154th annual meeting & exhibition supplemental proceedings N2 - This study examines the impact of different hatching strategies on the mechanical and technological properties, as well as the manufacturing-induced residual stresses of additively manufactured AlSi10Mg components produced using Laser Powder Bed Fusion (LPBF). For the sample production, parallel and orthogonal hatching patterns were employed at various rotation angles, leading to differences in the mechanical properties of the components. The parallel structure exhibits significantly higher compressive residual stresses in the near-surface areas of the component, up to 33% greater than those observed in the orthogonal structure. These compressive residual stresses could counteract operational tensile stresses, potentially enhancing the load-bearing capacity of the component. The findings of this study provide insights into the targeted use of hatching strategies to optimize the mechanical properties and lifespan of components. Future works should focus on experimentally validating the simulation results using the core hole method to further improve the correlation between numerical models and actual stress distributions. Y1 - 2025 SN - 9783031807473 U6 - https://doi.org/10.1007/978-3-031-80748-0_15 SN - 2367-1181 SP - 170 EP - 181 PB - Springer CY - Cham ER - TY - INPR A1 - Vogl, Yannick A1 - Schulz, Carsten A1 - Schaeffer, Thomas A1 - Geiger, Benjamin T1 - Prediction of the wear behavior of a conveyor belt with flexible rollers N2 - This paper introduces a method to predict wear behavior in conveyor belt systems using a lumped mass modeling approach. While previous research has focused primarily on lateral belt walking, this study shifts attention to belt deformation and its associated wear. Both significantly affect system efficiency and component lifespan. The authors propose using local frictional power as a wear indicator, leveraging its direct relation to frictional work in established wear models. To validate the method, the study simulates a conveyor belt with three flexible rollers and a deformable belt modeled through rigid spheres connected by spring-damper elements. The authors quantify and visualize frictional power density across the belt width, distinguishing between running and transverse directions. The results demonstrate that the frictional power distribution depends heavily on discretization quality, particularly due to the polygon effect inherent in the lumped mass approach. A convergence analysis reveals a minimum discretization of nine sphere rows with 557 spheres per row to achieve reliable qualitative insights. This method enables researchers to evaluate wear distribution in flexible conveyor systems and adapt the approach for broader applications in multibody dynamics. Future work should refine discretization techniques and friction models to enhance quantitative accuracy. Y1 - 2025 U6 - https://doi.org/10.21203/rs.3.rs-6343500/v1 N1 - Der Aufsatz wurde peer-reviewed veröffentlicht und ist ebenfalls in diesem Repositorium verzeichnet unter: https://opus4.kobv.de/opus4-oth-regensburg/8489 PB - Research Square Platform LLC ER - TY - CHAP A1 - Schulz, Carsten A1 - Schwarz, Colin T1 - Indirect Model Predictive Control and its Impact on the Fatigue Strength of the Drivetrain T2 - 10. VDI-Fachtagung Schwingungen von Windenergieanlagen 2019 : Bremen, 04.-05. Juni 2019 Y1 - 2019 SN - 978-3-18-092346-8 ER - TY - CHAP A1 - Schwarz, Colin A1 - Schulz, Carsten ED - Schlecht, Berthold T1 - Indirekte nichtlineare Modellprädiktive Regelung von Windkraftanlagen und deren Einfluss auf die Betriebsfestigkeit beteiligter Maschinenelemente T2 - DMK - Dresdner Maschinenelemente Kolloquium, 2017, Dresden Y1 - 2017 PB - sierke-Verlag ER - TY - JOUR A1 - Walter, Stefanie A1 - Schwanzer, Peter A1 - Hagen, Gunter A1 - Rabl, Hans-Peter A1 - Dietrich, Markus A1 - Moos, Ralf T1 - Combined Ash and Soot Monitoring for Gasoline Particulate Filters Using a Radio-Frequency-Based Sensor JF - Emission Control Science and Technology N2 - Increasingly stringent emission limits have made particulate filters necessary for gasoline engines. Similar to diesel applications, gasoline particulate filters (GPFs) can be monitored by differential pressure measurement or by the radio-frequency-based filter diagnosis (RF sensor). In addition to measuring the soot loading, ash detection is critical for monitoring the GPF over the entire vehicle lifetime. Because the RF sensor detects the filter loading through a change in the dielectric properties of the GPF, it can detect not only soot but also ash. In diesel applications, the RF sensor has already demonstrated its potential for ash detection. To verify the feasibility of simultaneous ash and soot monitoring for GPFs, filters were loaded with ash on an engine test bench and measured on a lab test bench under defined synthetic exhaust gas conditions. By evaluating resonant modes, soot and ash could be clearly distinguished, as ash mainly affects the resonant frequency, while soot also changes the quality factor due to its high dielectric losses. However, higher soot loadings could not be detected by the resonant parameters, but instead by a frequency-averaged transmission signal. While the presence of ash caused an offset in this signal, its sensitivity to soot was not affected. Thus, the influence of ash can be corrected if the signal in the soot-free filter state is known, e.g., from the behavior of the resonant parameters. Therefore, even with a continuously increasing ash loading over the lifetime of a vehicle, an accurate soot detection is possible with the RF sensor. KW - Gasoline particulate flter KW - Radio-frequency KW - Soot mass determination KW - Ash detection Y1 - 2023 U6 - https://doi.org/10.1007/s40825-023-00235-y PB - Springer ER - TY - CHAP A1 - Schwarz, Colin A1 - Schulz, Carsten T1 - Moderne, schädigungsreduzierende Ansätze zur Regelung einer Windenergieanlage in einem breiten Lastspektrum T2 - Dresdner Maschinenelemente Kolloquium : DMK 2019 : 26.-27. Nov. Y1 - 2019 SN - 978-3-96548-055-1 SP - 601 EP - 616 PB - Sierke Verlag CY - Göttingen ER - TY - GEN A1 - Walter, Stefanie A1 - Schwanzer, Peter A1 - Hagen, Gunter A1 - Rabl, Hans-Peter A1 - Dietrich, Markus A1 - Moos, Ralf T1 - Combined Ash and Soot Monitoring in Gasoline Particulate Filters with a Radio-Frequency-Based Sensor T2 - SAE World Congress Experience, April 5-7, 2022, Detroit, Michigan, USA N2 - In recent years, it turned out that primarily the number of ultrafine particles and not their mass is relevant in terms of harmful health effects. Therefore, exhaust emission standards are constantly being tightened with regard to the particulate number. To meet the emission limits, particulate filters have become necessary for gasoline engines. Similar to diesel applications, gasoline particulate filters (GPFs) can be monitored via differential pressure measurement or via a radio-frequency approach (RF-sensor). The latter is based on the influence of the soot conductivity on the electromagnetic field. To control the GPF, ash detection is of crucial importance besides the soot load monitoring. With the differential pressure system, this is only possible with high uncertainties due to the low pressure increase caused by ash. The RF-sensor, however, has already demonstrated its potential for ash detection in diesel applications. In order to verify the applicability of the system for GPFs, filters were loaded via a method for fast ash loading. Thereby, it was shown that by evaluating resonant modes – especially the resonant frequency – the ash loading can easily be measured as long as the filter is soot-unloaded. In contrast, soot loading can be determined independently from this by considering a frequency-averaged transmission signal between the antennas of the RF-sensor. Using a setup for radio-frequency material characterization, the dielectric parameters of the generated ash were also measured. In comparison with the properties of the synthetic soot PrintexU, ash showed significantly lower dielectric losses. Thus, the evaluation of the loss-dependent quality factor, which is only possible at low soot loadings, allows a precise conclusion whether the filter is completely soot-free. Furthermore, using synthetic soot loading, it could be shown that soot detection via the averaged transmission signal is not affected by ash. In summary, it could be shown that with the RF-sensor, ash and soot can be simultaneously detected. Y1 - 2022 UR - https://eref.uni-bayreuth.de/id/eprint/69506 ER - TY - GEN A1 - Krefting, Dagmar A1 - Zaunseder, Sebastian A1 - Säring, Dennis A1 - Wittenberg, Thomas A1 - Palm, Christoph A1 - Schiecke, Karin A1 - Krenkel, Lars A1 - Hennemuth, Anja A1 - Schnell, Susanne A1 - Spicher, Nicolai T1 - Blutdruck, Hämodynamik und Gefäßzustand: Innovative Erfassung und Bewertung – Schwerpunkt bildbasierte Verfahren T2 - 66. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie e. V. (GMDS), 12. Jahreskongress der Technologie- und Methodenplattform für die vernetzte medizinische Forschung e. V. (TMF), 26. - 30.09.2021, online N2 - Einleitung: Blutdruck gilt als sogenannter Vitalparameter als einer der grundlegenden Indikatoren für den Gesundheitszustand einer Person. Sowohl zu niedriger als auch zu hoher Blutdruck kann lebensbedrohend sein, letzerer ist darüber hinaus ein Risikofaktor insbesondere für Herz-Kreislauferkrankungen, die trotz wichtiger Fortschritte in der Behandlung immer noch die häufigste Todesursache in Deutschland darstellen. Die Hämodynamik, also die raumzeitliche Dynamik des Blutflusses, und der Gefäßzustand sind eng verbunden mit dem Blutdruck und ebenfalls von hoher klinischer Relevanz, u.a. zur Identifikation von Durchblutungsstörungen und ungünstigen Druckverteilungen der Gefäßwand. Innovationen in der Messtechnik als auch in der Datenanalyse bieten heute neue Möglichkeiten der Erfassung und Bewertung von Blutdruck, Hämodynamik und Gefäßzustand [1], [2], [3], [4]. Methodik: In einer gemeinsamen Workshopserie der AG Medizinische Bild- und Signalverarbeitung der GMDS und des Fachausschusses Biosignale der DGBMT werden wir neue Ansätze und Lösungen für Mess- und Analyseverfahren zu Blutdruck und -fluss sowie zum Gefäßzustand vorstellen und diskutieren. Dabei stehen im ersten Workshop auf der GMDS Jahrestagung Bildbasierte Verfahren im Zentrum, während der zweite Workshop auf der DGBMT Jahrestagung den Fokus auf Biosignalbasierten Verfahren legt. Es werden aktuelle Forschungsergebnisse vorgestellt und diskutiert. Es sind jeweils mehrere Vorträge geplant mit ausreichend Zeit zur Diskussion. Folgende Vorträge sind geplant (Arbeitstitel): Sebastian Zaunseder: Videobasierte Erfassung des Blutdrucks Anja Hennemuth: A Visualization Toolkit for the Analysis of Aortic Anatomy and Pressure Distribution Lars Krenkel: Numerische Analyse der Rupturwahrscheinlichkeit zerebraler Aneurysmata Susanne Schnell: Messung des Blutflusses und hämodynamischer Parameter mit 4D flow MRI: Möglichkeiten und Herausforderungen Ergebnisse: Ziel des Workshops ist die Identifikation von innovativen Ansätzen und neuen Methoden zur qualitativen und quantitativen Bestimmung von hämodynamischen Parametern sowie deren kritische Bewertung durch die Community für die Eignung in der klinischen Entscheidungsunterstützung. Diskussion: Der Workshop leistet inhaltlich einen Beitrag zu zentralen Aspekten für die Herz-Kreislauf-Medizin. Er bringt dabei Expertise aus verschiedenen Bereichen zusammen und schlägt die Brücke zwischen Kardiologie, Medizininformatik und Medizintechnik. Schlussfolgerung: Innovative Technologien aus Medizintechnik und Informatik ermöglichen zunehmend einfache und raumzeitlich aufgelöste Erfassung und Bewertung wichtiger Informationen zur Unterstützung von Diagnose und Therapieverfolgung. [1] Zaunseder S, Trumpp A, Wedekind D, Malberg H. Cardiovascular assessment by imaging photoplethysmography - a review. Biomed Tech (Berl). 2018 Oct 25;63(5):617–34. [2] Huellebrand M, Messroghli D, Tautz L, Kuehne T, Hennemuth A. An extensible software platform for interdisciplinary cardiovascular imaging research. Comput Methods Programs Biomed. 2020 Feb;184:105277. [3] Schmitter S, Adriany G, Waks M, Moeller S, Aristova M, Vali A, et al. Bilateral Multiband 4D Flow MRI of the Carotid Arteries at 7T. Magn Reson Med. 2020 Oct;84(4):1947–60. [4] Birkenmaier C, and Krenkel, L. Flow in Artificial Lungs. In: New Results in Numerical and Experimental Fluid Mechanics XIII. Contributions to the 22nd STAB/DGLR Symposium. Springer; 2021. KW - Bildbasierte Verfahren KW - Blutdruck KW - Hämodynamik KW - Blutgefäß KW - Bildgebendes Verfahren Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0183-21gmds0167 ER - TY - JOUR A1 - Esper, Lukas A1 - Schultheiss, Ulrich A1 - Grad, Marius A1 - Noster, Ulf A1 - Bund, Andreas T1 - Application of the Hull Cell for Identifying Electropolishing Parameters to Adjust Surface Morphology in Additive Manufacturing JF - ECS Advances N2 - Additively processed materials are increasingly used to manufacture customized parts, e.g. medical implants. Implant surfaces often require a smooth finish, which can be achieved by post-processing and well-defined process parameters. In this study, the effects of electropolishing of metal parts produced by laser powder bed fusion are investigated using Hull cell experiments and a three-electrode setup. Current density voltage curves were measured with the three-electrode setup to identify the regimes for electropolishing. Subsequently different constant-currents were applied and Hull cell experiments were conducted. The surface roughness (Sz, Sa) and the mass removal were analysed. Surface morphologies were assessed using laser scanning and scanning electron microscopy. A reduction of the initial surface roughness of more than 90% to Sa < 0.3 μm has been achieved. Considering the passed electrical charge during electropolishing, results from Hull cell experiments are systematically correlated with current-controlled electropolishing. This approach enables the precise tailoring of polishing parameters to achieve surfaces with defined roughness. Furthermore, the study demonstrates the suitability of Hull cells in determining electropolishing parameters for additive materials and highlights their contribution to post-processing in additive manufacturing. Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-86295 SN - 2754-2734 N1 - Corresponding author der OTH Regensburg: Lukas Esper VL - 4 IS - 4 PB - The Electrochemical Society ER - TY - JOUR A1 - Gersch, Sebastian A1 - Noster, Ulf A1 - Schulz, Carsten A1 - Bagdahn, Jörg T1 - Influence of the Process-Related Surface Structure of L-PBF Manufactured Components on Residual Stress Measurement Using the Incremental Hole Drilling Method JF - Applied Sciences N2 - Laser Powder Bed Fusion (L-PBF) parts combine geometric freedom with process-induced rough surfaces that challenge residual-stress metrology. We evaluated the accuracy of the incremental hole-drilling (IHD) method with electronic speckle pattern interferometry (ESPI) by applying defined stresses via four-point bending to stress-relieved AlSi10Mg coupons, rather than measuring unknown process stresses. Flat specimens (2 mm, thin per ASTM E837) were analyzed on up-skin, side-skin, and CNC-milled surfaces; thin-specimen calibration coefficients were used. After a preliminary inter-specimen check (three specimens per surface; spread < 8 MPa), one representative specimen per surface was tested with three drill sites to assess intra-specimen uniformity. Measured IHD–ESPI stresses agreed best at 70 MPa: deviations were ~4.1% (up-skin), 6.0% (side-skin), and 6.24% (CNC-milled). At 10 MPa the relative errors increased (23.6%, 18.4%, and 1.40%), consistent with reduced ESPI signal-to-noise and fixture compliance in the low-stress regime. At 140 MPa, deviations rose again (21.1%, 14.3%, and 13.1%), reflecting operation near the ~60% Rp0.2 elastic limit of hole-drilling and potential local plasticity. Surface-dependent artifacts also mattered as follows: the side-skin required no coating and performed comparably to CNC-milled, whereas the up-skin’s roughness plus matting spray introduced fringe distortions and chip/coating debris near the hole. This controlled study indicates that IHD–ESPI can provide reliable results on L-PBF AlSi10Mg in the mid-stress range when surface preparation, coating, and rig compliance are carefully managed. Limitations include excluding down-skin surfaces and testing only one specimen per condition; thus, results should be generalized cautiously. KW - L-PBF KW - residual stress KW - hole drilling method KW - surface roughness KW - surface condition KW - AlSi10Mg Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-84929 SN - 2076-3417 VL - 15 IS - 18 PB - MDPI ER - TY - THES A1 - Grad, Marius T1 - Oberflächenmodifikation von Titanbasiswerkstoffen durch das Eindiffundieren von Kohlenstoff N2 - Titan und seine Legierungen finden aufgrund ihrer geringen Oberflächenhärte vorwiegend in wenig verschleißbeanspruchten Bereichen Anwendung. Zur Erhöhung der Härte werden oft Verschleißschutzschichten durch chemische oder physikalische Gasphasenabscheidung eingesetzt. Diese Schichten weisen jedoch mitunter eine schlechte Haftung auf, was zu vorzeitigem Versagen führen kann. Eine Alternative bietet das Diffusionsschweißen, bei dem durch den Konzentrationsgradienten verschiedener Elemente eine Diffusionsschicht zwischen Titan und einem Fügepartner entsteht. Bei hochkohlenstoffhaltigen Stählen bildet sich an der Grenzfläche eine TiC-Schicht. Durch chemisches Auflösen des Stahls kann diese Schicht freigelegt und genutzt werden. Jedoch ist dieses Verfahren noch nicht gänzlich untersucht. Verschiedene Veröffentlichungen treffen widersprüchliche Aussagen, ob neben TiC auch Eisen-Titan-Verbindungen (FeTi oder Fe2Ti) entstehen. Neben der Zusammensetzung ist auch die Mikrostruktur der entstehenden Schicht nicht abschließend untersucht. Ziel dieser Arbeit ist es, das Schichtwachstum anhand thermodynamischer Gesetzmäßigkeiten zu untersuchen. Dabei werden der Einfluss von Temperatur, Zeit und Kohlenstoffkonzentration auf das Diffusionsverhalten und die Schichtbildungsgeschwindigkeit analysiert. Besonders relevant ist, dass der Kohlenstoff in interstitieller Form vorliegt. Die Schichtbildungskinetik wird bildgebend untersucht. Die chemische Zusammensetzung wird mittels Glimmentladungsspektroskopie (GDOES) und energiedispersiver Röntgenspektroskopie (EDS) bestimmt, während die Phasenanalyse durch Röntgendiffraktometrie (XRD) erfolgt. Zur Charakterisierung der Mikrostruktur werden EBSD-Messungen herangezogen. Nanoindentation dient der Ermittlung mechanischer Kennwerte wie E-Modul und Härte. Die Ergebnisse zeigen, dass der Kohlenstoffgehalt des Stahls die Schichtbildung wesentlich beeinflusst. Ein hoher Kohlenstoffanteil kann die Bildung intermetallischer Fe-Ti-Verbindungen unterdrücken. Die mikrostrukturellen Eigenschaften können hingegen nur durch die Prozessparameter (Temperatur und Zeit) beeinflusst werden. Die mechanischen Kennwerte sind nur durch die Phasenzusammensetzung der Schicht, welche in großen Teilen konstant ist, bestimmt. Durch das chemische Entfernen des Stahlsubstrats aus dem Verbund und dem damit einhergehenden Freilegen der Schicht, stellt das Verfahren des Diffusionsschweißens eine alternative Möglichkeit der Beschichtung von Titanbasiswerkstoffen dar. Die vorliegenden Untersuchungen belegen, dass der Prozess bestimmten Grenzen unterliegt, dieser jedoch innerhalb des erarbeiteten Prozessfensters beherrschbar ist. Dies ist der Grund, weshalb dem Diffusionsschweißen großes Potenzial im Bereich der Beschichtungstechnik zuzuordnen ist. KW - Diffusionsschweißen KW - Titancarbid KW - Röntgendiffraktometrie Y1 - 2025 U6 - https://doi.org/10.22032/dbt.66089 N1 - Dissertation, Technische Universität Ilmenau, 2025 PB - Technische Universität Ilmenau CY - Ilmenau ER - TY - JOUR A1 - Wagner, Marcus A1 - Franke, Markus A1 - Krause, Tom Janis A1 - Heinle, Ingo T1 - Data augmentation of material properties for machine learning in industrial production - a case study in an automotive press shop JF - Engineering Computations : International journal for computer-aided engineering and software N2 - In the context of industrial production, the utilisation of data recording and processing techniques is becoming increasingly prevalent across the manufacturing sector. The solutions integrate sensors, facilitate the transmission of data, and enable data-driven decision-making, thereby reducing downtime and optimising quality. However, challenges emerge due to the limited non-transferable data or models between processes. Alterations to the production process can render collected data invalid, resulting in restricted datasets and potential overfitting. To address these issues, techniques such as data augmentation are employed. This study aims to develop a data augmentation methodology applicable in dynamic, data-scarce production environments, enhancing the robustness of regressor predictions. KW - Data augmentation KW - Machine learning KW - Manufacturing KW - Deep drawing Y1 - 2025 U6 - https://doi.org/10.1108/EC-08-2024-0787 PB - Emerald Publishing CY - Leeds ER - TY - CHAP A1 - Stocker, Philipp A1 - Lehrer, Tobias A1 - Duddeck, Fabian A1 - Wagner, Marcus T1 - Face-wise prediction of sheet-metal drawability using graph neural networks T2 - Journal of Physics: Conference Series N2 - The early design phase of deep-drawn structural components involves time-consuming iterative development. Traditional drawability assessments rely on finite element simulations, which are computationally expensive and slow the design process. Alternative machine learning (ML) approaches show promise in accelerating this process but face challenges with existing methods. Existing low-dimensional ML models only provide global predictions without identifying specific geometric regions prone to failure. High-dimensional models provide local predictions but require significant amounts of training data. We propose a data-driven approach leveraging graph neural networks (GNNs) for face-wise drawability prediction of sheet metal components in their computer-aided design (CAD) representation. Our method aims to bridge the gap between the computational efficiency of ML and the spatial resolution of simulation by providing face-wise insight into potential failure regions. This study utilises a dataset of parametric U-channel geometries with variability in both geometry and topology. Ground-truth labels are generated using inverse analysis simulations. Geometric entities are represented through the use of UV parameterisations, whereby 3D surfaces are mapped into 2D space to facilitate geometric encoding. Concurrently, the topological relationships are captured using a face adjacency graph. To address data scarcity, we evaluate how different amounts of training data affect model performance and perform ablation studies to analyse the impact of different CAD representation features. Our results show that the proposed approach achieves high accuracy even with limited training data. In addition, the ablation studies provide insights into the most critical CAD features, guiding future research. These results highlight the potential of our GNN to predict face-wise drawability in the early design phase. Y1 - 2025 U6 - https://doi.org/10.1088/1742-6596/3104/1/012053 SN - 1742-6588 N1 - Corresponding author der OTH Regensburg: Philipp Stocker VL - 3104 IS - 1 PB - IOP Publishing ER - TY - JOUR A1 - Lehle, Karla A1 - Philipp, Alois A1 - Krenkel, Lars A1 - Gruber, Michael A1 - Hiller, Karl-Anton A1 - Müller, Thomas A1 - Lubnow, Matthias T1 - Thrombocytopenia During Venovenous Extracorporeal Membrane Oxygenation in Adult Patients With Bacterial, Viral, and COVID-19 Pneumonia JF - ASAIO Journal N2 - Contact of blood with artificial surfaces triggers platelet activation. The aim was to compare platelet kinetics after venovenous extracorporeal membrane oxygenation (V-V ECMO) start and after system exchange in different etiologies of acute lung failure. Platelet counts and coagulation parameters were analyzed from adult patients with long and exchange-free (≥8 days) ECMO runs (n = 330) caused by bacterial (n = 142), viral (n = 76), or coronavirus disease 2019 (COVID-19) (n = 112) pneumonia. A subpopulation requiring a system exchange and with long, exchange-free runs of the second oxygenator (≥7 days) (n = 110) was analyzed analogously. Patients with COVID-19 showed the highest platelet levels before ECMO implantation. Independent of the underlying disease and ECMO type, platelet counts decreased significantly within 24 hours and reached a steady state after 5 days. In the subpopulation, at the day of a system exchange, platelet counts were lower compared with ECMO start, but without differences between underlying diseases. Subsequently, platelets remained unchanged in the bacterial pneumonia group, but increased in the COVID-19 and viral pneumonia groups within 2–4 days, whereas D-dimers decreased and fibrinogen levels increased. Thus, overall platelet counts on V-V ECMO show disease-specific initial dynamics followed by an ongoing consumption by the ECMO device, which is not boosted by new artificial surfaces after a system exchange. Y1 - 2025 U6 - https://doi.org/10.1097/MAT.0000000000002383 SN - 1058-2916 SN - 1538-943X PB - Wolters Kluwer ER - TY - GEN A1 - Dendorfer, Sebastian T1 - Towards a deeper understanding of Pelvic Floor Disorders via Biomechanical Models Y1 - 2025 ER - TY - GEN A1 - Dendorfer, Sebastian T1 - Zahlen statt Meinung – virtuelle Ganzkörpermodelle für die Mensch-Fahrzeug-Interaktion Y1 - 2025 ER - TY - CHAP A1 - Galka, Stefan A1 - Weigert, Alexander ED - Schmidt, Thorsten ED - Kühn, Mathias ED - Rank, Sebastian T1 - Systematik zur planungsbegleitenden Simulation bei der Konzeptplanung von Produktionssystemen – ein Anwendungsfall aus der Elektrolysestack-Produktion T2 - Simulation in Produktion und Logistik 2025 N2 - Simulation can support early-stage production system planning by enabling efficient evaluation of concept variants. However, detailed models are often impractical in concept phases due to limited data and high modelling effort. This paper presents a structured three-stage simulation approach for supporting the concept planning of water electrolyzer stack production systems . The approach leverages automatic model generation from formal process descriptions and gradually increases model detail across stages, carried out through a custom-developed simulation framework. This enables early validation of the throughput capability, resource planning, and the analysis of stochastically occurring technical malfunction. The method aims to reduce planning time while improving decision quality. KW - Produktion, Simulation, Petri-Netz Y1 - 2025 SN - 978-3-86780-806-4 U6 - https://doi.org/10.25368/2025.278 SP - 45-1 EP - 45-10 PB - Technische Universität Dresden, Professur für Technische Logistik CY - Dresden ER - TY - CHAP A1 - Galka, Stefan A1 - Meißner, Sebastian ED - Schmidt, Thorsten ED - Rank, Sebastian ED - Kühn, Mathias T1 - Einsatz von Digitalen Zwillingen für die operative Steuerung von innerbetrieblichen Transportsystemen T2 - Simulation in Produktion und Logistik 2025 N2 - This paper presents the architecture and functionality of a simulation-based Digital Twin designed to support decision-making in the control of internal transport systems. The developed Digital Twin leverages a wide range of data from operational information systems to predict future system loads. Specific methods for forecasting transport orders have been developed. An integrated simulation framework enables analysis of potential control decisions, such as resource allocation or the timing of order releases. The simulation results are used for multi-criteria evaluation of the available options for preventive action, thus, providing users with concrete recommendations to support their operational decision-making processes. KW - Digital Twin, Simulation, Logistics Y1 - 2025 SN - 978-3-86780-806-4 U6 - https://doi.org/10.25368/2025.280 SP - 47-1 EP - 47-11 PB - Technische Universität Dresden, Professur für Technische Logistik CY - Dresden ER - TY - CHAP A1 - Galka, Stefan A1 - Weigert, Alexander T1 - Petri Net Structures for Automated Model Generation through Process Descriptions T2 - IFAC Papers OnLine N2 - Creating simulation models and running experiments requires expertise and significant effort. Modelling complex production systems by using Petri Nets, which have a simple formalism, leads to considerable modelling effort. To reduce the workload required, fundamental processes within a production system must be analyzed and represented as generic Petri Net structures to enable their automatic generation. These structures can serve as modular building blocks to construct arbitrarily complex systems. The broader objective is to enable the automatic generation of such, based on process descriptions within a simulation framework. Built on these findings, the necessary information for developing a specialized formal process description is derived, enabling the automated generation of Petri Net simulation models for production systems. KW - Digital Twin, Simulation, Logistics Y1 - 2025 U6 - https://doi.org/10.1016/j.ifacol.2025.09.093 VL - 59 IS - 10 SP - 542 EP - 547 PB - Elsevier ER - TY - CHAP A1 - Galka, Stefan T1 - Integration and usage of simulation-based digital twins in internal logistics systems T2 - IFAC Papers OnLine N2 - This paper presents the workflows of Digital Twins in practice, with reference to three case studies. The objective is to present the processing of data and information flow. The most essential requirements for the design of a Digital Twin are synthesized from the case studies and a layer model is presented, which was developed based on the three case studies. The model consists of four functional layers and an overarching data- and workflow-management-backbone. A front-end layer is proposed for communication with the end user. KW - Digital Twin, Simulation, Logistics Y1 - 2025 U6 - https://doi.org/10.1016/j.ifacol.2025.09.152 VL - 59 IS - 10 SP - 897 EP - 902 PB - Elsevier ER - TY - JOUR A1 - Bartsch, Alexander A1 - Eigenberger, Andreas A1 - Felthaus, Oliver A1 - Booth, Brian W. A1 - Krenkel, Lars A1 - Schratzenstaller, Thomas A1 - Prantl, Lukas T1 - Quantification of Cannula Influence on Negative Pressure in Syringe Assisted Liposuction JF - Plastic & Reconstructive Surgery N2 - To make the results of the autologous fat transfer more satisfactory, all parameters of suction, preparation, and reapplication must be well understood. Since syringe-assisted liposuction is frequently used for small-volume procedures, we quantified the influence of the cannula on negative pressure. For these experiments, we used a digital manometer to which a syringe and one of seven different cannulas were connected. Data was collected and analyzed using LabVIEW and Matlab. The volume of our measurement setup was calculated using Boyle-Mariotte's law to ease interpretation, which revealed a volume of 2.82 ± 0.03 mL. We demonstrate that the volume of the measurement setup significantly affects the measurement results. Consequently, we accounted for this factor and calculated the theoretical values accordingly. Statistical analysis shows a significant influence on negative pressure across different cannulas, except for two pairs, which had minimal volume differences. Exemplary, for cannulas with volumes under 1.75 mL, a 2 mL syringe plunger pull was sufficient to create a - 0.5 bar (- 14.8 inHg) negative pressure. The present data indicate that the size of the suction cannula must be considered in syringe-assisted suction to ensure a specific negative pressure is not exceeded. Other research groups have demonstrated that adipocyte vitality and the amount of stromal vascular fraction are reduced by excessively strong negative pressure. Y1 - 2025 U6 - https://doi.org/10.1097/PRS.0000000000012477 SN - 0032-1052 PB - American Society of Plastic Surgeons ER - TY - GEN A1 - Merker, Lukas A1 - Böhm, Valter A1 - Zentner, Lena T1 - A tensegrity-based elastic joint element T2 - IFToMM WC 2023 - The 16th World Congress of the International Federation for the Promotion of Mechanism and Machine Science, 5-10 November, Tokyo, Japan Y1 - 2023 ER - TY - JOUR A1 - Ginster, Vinzenz A1 - Weigert, Alexander A1 - Heym, Maximilian Klaus A1 - Beier, Christoph Jürgen Anton A1 - Schiebahn, Alexander A1 - Galka, Stefan T1 - Factory simulation of adhesive bonding processes considering pot-life-induced waste JF - Journal of Advanced Joining Processes N2 - The simulation of production systems in the planning phase is an established tool for evaluating system performance under dynamic conditions (Da Silva et al., 2018). When planning a production system that includes time-critical processes such as adhesive bonding, exceeding time constraints (e.g., excessive lead times relative to the adhesive pot-life) can lead to product rejection and scrap. These risks should be analyzed by means of simulation, as it enables the consideration of stochastic effects such as random machine breakdowns, which significantly influence product lead times. This study focuses on the production of adhesively bonded electrolyzer-cells. Due to the cell design, several handling and stacking operations must be carried out between adhesive application and final joining, so that immediate joining is not feasible and pot-life-induced scrap becomes a critical risk factor. We therefore conducted an exploratory investigation that combines experimental pot-life characterization with discrete-event simulation of a planned electrolyzer-cell production system. A two-component epoxy adhesive was characterized using differential scanning calorimetry with kinetic analysis, rotational rheometry, and 90° peel tests on application-representative joints. Based on these tests, an application-specific pot-life was derived and implemented as a time-dependent quality criterion in the discrete-event simulation model. A full-factorial simulation study with varied buffer size and mean time to repair at a station availability of 98 % was carried out. The results demonstrated a pronounced trade-off between throughput and pot-life-induced waste and identified a buffer capacity of one and short repair times as the most favorable configuration. Extending pot-life due to different processing temperatures substantially reduced scrap, highlighting the benefit of integrating curing kinetics and dynamic simulation in early-stage production system design for time-critical adhesive processes. KW - Digital Twin, Simulation, Logistics Y1 - 2026 U6 - https://doi.org/10.1016/j.jajp.2026.100375 SN - 2666-3309 VL - 13 PB - Elsevier ER - TY - CHAP A1 - Galka, Stefan A1 - Meißner, Sebastian T1 - Simulation-Based Digital Twins for Internal Transport Systems T2 - Procedia Computer Science N2 - The increasing complexity of internal transport systems in industrial applications poses significant challenges for operational decision-making. This paper presents a simulation-based Digital Twin framework developed within the research project TwinTraSys to support the control of such systems. The framework is specifically tailored to the constraints of real-world IT infrastructures, requiring minimal transaction data, while enabling predictive analysis and dynamic scenario evaluation. It consists of a modular architecture divided into four core components: data provision, data preparation, simulation, and decision support. A dedicated simulation framework enables the automated generation of structural models and the integration of real-world operational control systems. The proposed approach has been validated in industrial settings and has demonstrated its ability to support resource planning and transport resource allocation through simulation-based experimentation and multi-criteria evaluation. This paper contributes to the practical advancement of Digital Twin applications in intralogistics by bridging the gap between theoretical models and real-world constraints. KW - Digital Twin KW - Intralogistics KW - Logistics KW - Operational Control KW - Simulation KW - Simulation-based Decision Support Y1 - 2025 U6 - https://doi.org/10.1016/j.procs.2025.12.016 N1 - Corresponding author der OTH Regensburg: Stefan Galka VL - 274 SP - 161 EP - 170 PB - Elsevier ER - TY - INPR A1 - Fischer, Johannes A1 - Hirsch, Thomas A1 - Reitmeier, Torsten A1 - Bierl, Rudolf T1 - Real-time hardware-based processing of high-precision detector signals for surface plasmon resonance spectroscopy N2 - Surface plasmon resonance (SPR) is limited by small-signal detectability and drift when subtraction occurs in software after digitization. We introduce an SPR detector that performs on-detector amplification and analog differential readout, eliminating moving parts and software-heavy correction. The hardware-native subtraction boosts the usable ADC range and suppresses illumination and environmental noise. In fixed-angle refractive-index steps (NaCl), the platform resolves Δn_min ≈ 1.8 × 10⁻⁷ RIU compared to 4.6–7.2 × 10⁻⁶ RIU on a commercial comparator and improves small-signal SNR by up to ∼5,000-fold, while remaining competitive at high signal levels. In a model IgG–BSA assay, the detector’s low noise floor clarifies early binding and equilibrium transitions. By generating inherently clean raw signals, this hardware-native approach dramatically enhances sensitivity and long-term stability for label-free biosensing and inline process analytics while rendering AI-based or complex post-processing entirely unnecessary. The concept generalizes across platforms and opens a compact route to robust, high-fidelity SPR in complex environments, with a clear path toward multi-wavelength and arrayed detectors for high-throughput chemical monitoring. KW - Drift-free SPR KW - Hardware-native sensing KW - Noise suppression KW - On-detector amplification KW - Small-signal detection KW - Surface plasmon resonance Y1 - 2025 U6 - https://doi.org/10.2139/ssrn.5971170 ER - TY - CHAP A1 - Lehmann, Lukas A1 - Herrmann, David A1 - Schaeffer, Leon A1 - Albaik, Mohammed A1 - Müller, Emily A1 - Rizzello, Gianluca A1 - Böhm, Valter T1 - Biomimetic Auxetic Compliant Tensegrity Metamaterial with Tunable Poisson's Ratio for the Application as a Soft Robotic Skin T2 - 2025 IEEE International Conference on Cyborg and Bionic Systems (CBS), Beijing, China ;10/17/2025 - 10/19/2025 N2 - The use of compliant tensegrity grids offers significant potential for adaptive and lightweight systems for applications in soft robotics. This paper presents foundational investigations into a new class of auxetic tensegrity metamaterials. This work demonstrates that the auxetic behavior of a tensegrity grid can be realized and tuned solely through the mechanical properties of tensioned members, without altering the equilibrium geometry, offering a key advantage over conventional auxetic structures with fixed topologies. To validate the concept, 3D-printed demonstrators are manufactured, tested and a possible application as a cylindrically shaped soft robotic skin is shown. Y1 - 2025 SN - 979-8-3315-9742-9 U6 - https://doi.org/10.1109/CBS65871.2025.11267590 SP - 188 EP - 193 PB - IEEE ER - TY - JOUR A1 - Korzec, Dariusz A1 - Freund, Florian A1 - Doelfs, Isabelle A1 - Zacherl, Florian A1 - Kudala, Lucas A1 - Rabl, Hans-Peter T1 - Low-Current High-Voltage Pulsed Atmospheric Arc Plasma Jet: Nanoparticle Emission from the Cathodic Spot JF - Plasma N2 - The atmospheric pressure plasma jet (APPJ) is a popular type of cold atmospheric plasma (CAP). APPJs based on a pulsed atmospheric arc (PAA) are widely spread in industrial processing. A plasma jet of this type, PlasmaBrush PB3 (PB3), is a subject of diverse research activities. The characteristic feature of PB3 is the generation of a low-current (300 mA), high-voltage (1500 V) pulsed (54 kHz) atmospheric arc. A gas flow vortex is used to stabilize the arc and to sustain the circular motion of the cathodic arc foot. During long periods of operation, nozzles acting as arc discharge cathodes erode. Part of the eroded material is emitted as nanoparticles (NPs). These NPs are not wanted in many processing applications. Knowledge of the number, type, and size distribution of emitted NPs is essential to minimize their emissions. In this study, NPs in the size range of 6 to 220 nm, emitted from four different nozzles operated with PB3, are investigated. The differences between the nozzles are in the eroded surface material (copper, tungsten, and nickel), the diameter of the nozzle orifice, the length of the discharge channel, and the position of the cathodic arc foot. Significant differences in the particle size distribution (PSD) and particle mass distribution (PMD) of emitted NPs are observed depending on the type and condition of the nozzle and their operating time. Monomodal and bimodal PMD models are used to approximate emissions from the nozzles with tungsten and copper cores, respectively. The skew-normal distribution function is deemed suitable. The results of this study can be used to control NP emissions, both to avoid them and to utilize them intentionally. KW - arc discharge KW - atmospheric pressure plasma jet (APPJ) KW - cathode erosion KW - cathodic spot KW - electrode erosion KW - low-current high-voltage pulsed atmospheric arc KW - nanoparticles KW - particle mass distribution (PMD) KW - particle number distribution (PND) KW - pulsed atmospheric arc (PAA) Y1 - 2025 U6 - https://doi.org/10.3390/plasma8040044 N1 - This article belongs to the Special Issue Feature Papers in Plasma Sciences 2025 VL - 8 IS - 4 PB - MDPI ER - TY - CHAP A1 - Schaeffer, Leon A1 - Liebrecht, Melanie A1 - Schmaußer, Theresa A1 - Herrmann, David A1 - Lehmann, Lukas A1 - Böhm, Valter T1 - Finite element analysis of a tensegrity joint model for the use in dynamic hand orthoses T2 - 2025 9th International Conference on Biomedical Engineering and Applications (ICBEA), Seoul, Republic of Korea, February 27 - March 2, 2025 N2 - Many current dynamic hand orthoses use single degree of freedom joints, such as hinge joints. Consequently, these orthoses can only partially replicate the complex, multi-axis range of motion of the hand. To overcome this limitation, one approach is to use prestressed compliant structures as the basis for orthoses. In order to be able to map the dynamic influences on the orthosis as well as to simulate everyday use, this article provides an overview of this orthosis concept and the most important aspects in the development of such an orthosis including the results of the modal analysis. Based on these theoretical investigations, the presented methodological approach can be used to develop initial prototypes of tensegrity-based hand orthoses. KW - Hand orthosis KW - Modal Analysis KW - Tensegrity Joint Y1 - 2025 UR - https://ieeexplore.ieee.org/document/11018707 SN - 979-8-3315-3571-1 U6 - https://doi.org/10.1109/ICBEA66055.2025.00016 SP - 41 EP - 48 PB - IEEE ER - TY - JOUR A1 - Afanasev, Anna A1 - Höfer, Philipp A1 - Holtmannspötter, Jens A1 - Zimmer, Felix A1 - Ehrlich, Ingo T1 - Development of a continuous fiber-reinforced 3D printing process with a 6-axis robot arm: Process design and equipment JF - The International Journal of Advanced Manufacturing Technology N2 - The utilisation of 3D printing processes in the fabrication of continuous fiber-reinforced composites confers a multitude of advantages, in particular flexible design based on structural requirements. In order to achieve greater flexibility, there is a necessity for 3D printing systems that allow for customisable material selection and fiber positioning. This paper presents the design of a robot-based 3D printing system that incorporates an in-situ impregnation line and flexibility regarding the machine code generation for fiber positioning. The development of the system enabled the attainment of an average fiber volume content of up to 37.12%. In the tensile tests, material characteristics up to E1 = 24.7 GPa and strength of up to RM1 = 0.51 GPa were determined. Y1 - 2026 U6 - https://doi.org/10.1007/s00170-025-17263-3 SN - 0268-3768 N1 - Corresponding author der OTH Regensburg: Anna Afanasev PB - Springer ER - TY - JOUR A1 - Hollweck, Christoph A1 - Leidinger, Lukas A1 - Hartmann, Stefan A1 - Wagner, Marcus A1 - Wüchner, Roland T1 - An analysis of the critical time step size for explicit dynamics using trimmed B-splines, LR-splines, and THB-splines JF - Computer Methods in Applied Mechanics and Engineering N2 - Isogeometric analysis (IGA) combined with explicit dynamics is increasingly used in academia and has already been successfully applied in industrial simulations, including crash and sheet-metal forming. Since explicit schemes are only conditionally stable, accurate estimation of the critical time step is essential for both stability and efficiency. Adaptive mesh refinement is widely used to balance accuracy and computational cost. In IGA, THB- and LR-splines break the tensor-product structure of standard B-splines and enable local refinement, but their effect on the critical time step under trimming has not been systematically studied - a key requirement for reliable time step estimation. We investigate the critical time step in explicit dynamic simulations using trimmed B-splines, LR-splines, and THB-splines, based on a lumped mass matrix obtained by simple row summation. One-dimensional bar, two-dimensional membrane, and trimmed shell models are analyzed to determine how trimming and local refinement influence element and system eigenfrequencies, which directly control the stable time step. Refined boundary elements in open knot vectors are identified as the main bottleneck. Trimming these elements can increase the stable time step, though certain trimming configurations introduce new restrictions. Results show that LR- and THB-splines impose time step constraints similar to B-splines, making them equally suitable for explicit simulations. We also present a general method for computing element-wise Bézier extraction operators for LR- and THB-splines, enabling straightforward integration into standard finite element solvers. The findings are validated through nonlinear sheet-metal forming simulations in LS-DYNA using shells discretized with trimmed B-, LR-, and THB-splines. This represents the first such application and demonstrates their practical feasibility for industrial use. Y1 - 2026 U6 - https://doi.org/10.1016/j.cma.2025.118656 SN - 0045-7825 N1 - Corresponding author der OTH Regensburg: Christoph Hollweck VL - 450 PB - Elsevier ER - TY - CHAP A1 - Galka, Stefan A1 - Wappler, Mona T1 - INTEGRATION OF CASH FLOW MANAGEMENT AND FURTHER ASPECTS OF THE SUPPLY CHAIN MANAGEMENT IN PRODUCTION SYSTEM DESIGN T2 - IFAC-PapersOnLine N2 - One major goal of production system design is to decide on space requirements in the plant. In this phase, detailed information about the supply chain network (e.g. which suppliers deliver which parts) is often unavailable. Nevertheless, typical decisions in supply chain management, like the definition of replenishment processes and quantities or make-or-buy decisions, impact space requirements and the capital investment in raw materials and should therefore be considered in factory and production planning. This research article proposes a simulation approach for a production simulation in which raw material replenishment is integrated to evaluate the capital investment and space requirements for raw materials. KW - Supply chain management KW - nventory control KW - Logistics in manufacturing KW - Factory planning Y1 - 2023 U6 - https://doi.org/10.1016/j.ifacol.2023.10.1687 SN - 2405-8963 VL - 56 IS - 2 SP - 947 EP - 952 PB - International Federation of Automatic Control. Published by Elsevier Ltd. CY - Yokohama ER - TY - JOUR A1 - Qiao, Yu A1 - Grad, Marius A1 - Nonn, Aida T1 - Toward an Efficient and Robust Process–Structure Prediction Framework for Filigree L-PBF 316L Stainless Steel Structures JF - Metals N2 - Additive manufacturing (AM), particularly laser powder bed fusion (L-PBF), provides unmatched design flexibility for creating intricate steel structures with minimal post-processing. However, adopting L-PBF for high-performance applications is difficult due to the challenge of predicting microstructure evolution. This is because the process is sensitive to many parameters and has a complex thermal history. Thin-walled geometries present an added challenge because their dimensions often approach the scale of individual grains. Thus, microstructure becomes a critical factor in the overall integrity of the component. This study focuses on applying cellular automata (CA) modeling to establish robust and efficient process–structure relationships in L-PBF of 316L stainless steel. The CA framework simulates solidification-driven grain evolution and texture development across various processing conditions. Model predictions are evaluated against experimental electron backscatter diffraction (EBSD) data, with additional quantitative comparisons based on texture and morphology metrics. The results demonstrate that CA simulations calibrated with relevant process parameters can effectively reproduce key microstructural features, including grain size distributions, aspect ratios, and texture components, observed in thin-walled L-PBF structures. This work highlights the strengths and limitations of CA-based modeling and supports its role in reliably designing and optimizing complex L-PBF components. Y1 - 2025 U6 - https://doi.org/10.3390/met15070812 SN - 2075-4701 VL - 15 IS - 7 PB - MDPI ER - TY - JOUR A1 - Kranz, Michael A1 - Wagner, Maria Stella A1 - Pointner, Daniel A1 - Haus, Moritz A1 - Lubnow, Matthias A1 - Lehle, Karla A1 - Krenkel, Lars T1 - Polymer embedding of membrane lungs for histological investigations of intra-device clot formation JF - Cardiovascular Medicine N2 - Extracorporeal membrane oxygenation (ECMO) is an invasive but potentially lifesaving treatment option for severe cardiac or respiratory failure. Despite its beneficial effect, coagulation-related complications, mainly due to clot formation, excessive bleeding and the accumulation of deposits in the membrane lung (ML) remain common, causing higher mortality. In this context, the formation of clots and other deposits in the ML is of particular interest. Previous histological examinations of the polymethylpentene fiber mats inside the ML could only be performed in a top view, prohibiting valid quantification and examination of the multi-layered deposits or fiber mat spanning structures. Our objective was the establishment of a polymer embedding to increase the mechanical stability of the deposits and thus enable cross-sectional microtome cutting through the ML hollow-fibers. Clinically used MLs (PLS, Getinge, Rastatt, Germany) were stabilized with a polymer resin (HistoCURE 8100). Specimens were cut out of the embedded MLs and microtome sections with a thickness of 10 µm were performed. In addition to standard histological staining with hematoxylin-eosin (HE) and Pappenheim (May-Grunwald-Giemsa), fluorescence DNA staining for nucleated cells with 4′,6-diamidino-2-phenylindole (DAPI) and SYTOX™ Green as well as immunohistochemical and immunofluorescence staining for the lysosomal enzyme myeloperoxidase (MPO) and von Willebrand factor (vWF) were established. The protocol provides a method for large volume embedding (400 mL). The cellular and extracellular deposits were securely fixed by the polymer scaffold allowing the examination of clots in MLs in native position which was not possible with conventional paraffin embedding. Multi-layered deposits and fiber mat spanning structures are no longer disrupted during specimen extraction and can now be quantified. Staining with HE, Pappenheim, DAPI, SYTOX™ Green, MPO, and vWF was successfully tested with this protocol. This method may be the foundation for new insights into the complex clotting phenomena observed in MLs KW - clot formation KW - ECMO KW - HistoCURE 8100 KW - histology KW - membrane lungs KW - polymer embedding KW - Technovit 8100 Y1 - 2026 U6 - https://doi.org/10.3389/fcvm.2026.1650978 VL - 13 PB - Frontiers CY - Lausanne ER - TY - RPRT A1 - Schuhegger, Lukas A1 - Galka, Stefan T1 - Herausforderungen von produzierenden Startups N2 - Startups bringen mit ihrer Dynamik und neuen innovativen Geschäftsmodellen frischen Wind in die deutsche Unternehmenslandschaft. Die disruptiven Ansätze gestalten die Zukunft und damit geraten sie immer weiter in den Fokus, unter anderem auch für Investoren. Das Ziel der Studie ist es, Zusammenhänge zwischen Herausforderungen und Eigenschaften von produzierenden Startups darzulegen. Dieses Wissen soll an andere Startups weitergegeben werden, um die Erfolgschancen in der Gründerszene zu erhöhen. Im Juli 2021 wurde hierzu eine Umfrage entworfen, um die Erfahrungen von Gründern und Startup-Mitarbeitern zu sammeln und die spezifischen Herausforderungen besser zu verstehen. KW - Unternehmensgründung KW - Produktion KW - Studie KW - Logistik KW - Herausforderungen KW - Herausforderung bei der Gründung KW - Technologie Start-ups KW - Hochlauf KW - Phasenmodell Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-88520 ER - TY - INPR A1 - Lehrer, Tobias A1 - Stocker, Philipp A1 - Duddeck, Fabian A1 - Wagner, Marcus T1 - UCSM: Dataset of U-Shaped Parametric CAD Geometries and Real-World Sheet Metal Meshes for Deep Drawing N2 - The development of machine learning (ML) applications in deep drawing is hindered by limited data availability and the absence of open-access benchmarks for validating novel approaches, including domain generalization over distinct geometries. This paper addresses these challenges by introducing a comprehensive U-shaped dataset tailored to this manufacturing process. Our U-Channel sheet metal (UCSM) dataset combines 90 real-world meshes with an infinite number of synthetic geometry samples generated from four parametric Computer-Aided Design (CAD) models, ensuring extensive geometry variety and data quantity. Additionally, a ready-to-use dataset for drawability assessment and segmentation is provided. Leveraging CAD and mesh data sources bridges the gap between sparse data availability and ML requirements. Our analysis demonstrates that the proposed parametric models are geometrically valid, and real-world and synthetic data complement each other effectively, providing robust support for ML model development. While the dataset is confined to U-shaped, thin-walled, deep drawing scenarios, it considerably aids in overcoming data scarcity. Thereby, it facilitates the validation and comparison of new geometry-generalizing ML methodologies in this domain. By providing this benchmark dataset, we enhance the comparability and validation of emerging methods for ML advancements in sheet metal forming. Y1 - 2025 U6 - https://doi.org/10.2139/ssrn.5268323 N1 - Zugehöriges Datenset: https://doi.org/10.5281/zenodo.15327950 PB - SSRN ER - TY - GEN A1 - Stocker, Philipp A1 - Lehrer, Tobias T1 - Machine Learning Dataset of U-Channel Sheet Metal Geometry Representations with Supervision Information for Drawability Assessment and Part Segmentation [Data set] N2 - The dataset contains 2533 geometries from four different parametric CAD models sampled from the U-Channel python package. The representations include the original CAD geometries (.step), graph binaries (.bin), meshes (.off), and point clouds (.xyz). Additionally, we provide labels for supervised learning use cases of local and global drawability assessment and part segmentation (.json) for all representations. Custom label computation for drawability assessment is enabled by the provided strains.zip file, which contains minor and major true strains for the given meshes. For more details, refer to the associated publication. Y1 - 2025 U6 - https://doi.org/10.5281/zenodo.15327950 N1 - Zugehörige Publikation: Lehrer, Tobias and Stocker, Philipp and Duddeck, Fabian and Wagner, Marcus, UCSM: Dataset of U-Shaped Parametric CAD Geometries and Real-World Sheet Metal Meshes for Deep Drawing (May 21, 2025). https://doi.org/10.2139/ssrn.5268323 ER - TY - JOUR A1 - Kuettner, Andreas A1 - Fischer, Samuel A1 - Laumer, Tobias T1 - Mechanical and structural characterization of heat-staked parts realized by selective laser sintering of polyamide 12 JF - The International Journal of Advanced Manufacturing Technology N2 - Heat staking is a joining process in which thermoplastic pins are formed by heat and pressure in a form-fitting and insoluble way. This study evaluates the mechanical performance and microstructure of selective laser sintered (SLS) polyamide 12 (PA 12) components before and after heat staking, compared with conventionally turned reference specimens. The components were characterized using tensile tests, micrographs, microscopy, and micro-CT measurements. For the tests, the forces and temperatures during heat staking were varied to determine the best process parameters. Tensile tests revealed that SLS joints achieved strengths of up to 33.6 MPa, approaching the 39.9 MPa of the turned references. Microstructural analysis showed a marked reduction in porosity due to heat staking. Porosity decreased from 3.9% to 1.56% at a staking force of 300 N and from 4.29% to 0.81% at 1000 N, highlighting the beneficial effect of increased force. These results demonstrate that heat staking parameters significantly influence local densification and mechanical performance, and that, under suitable conditions, SLS components can achieve joint strengths comparable to conventionally manufactured parts. The study shows that the heat staking process parameters have a significant influence on the local microstructure and thus on the mechanical performance and provides a basis for optimizing SLS components for new heat staking applications. KW - Additive manufacturing KW - Heat staking KW - Material qualification KW - Polyamid 12 (PA) KW - Selective laser sintering (SLS) Y1 - 2026 U6 - https://doi.org/10.1007/s00170-025-17319-4 PB - Springer ER - TY - CHAP A1 - Galka, Stefan A1 - Strassburger, Steffen A1 - Lang, Sebastian A1 - Reggelin, Tobias ED - Bui, Tung T1 - Introduction to the Minitrack on Simulation Modeling and Digital Twins for Decision Making in the Age of Industry 4.0 T2 - Proceedings of the 57th Hawaii International Conference on System Sciences (HICSS), January3-6, 2024, Honolulu, Hawaii N2 - The minitrack contains contributions with a focus on simulation modeling and digital twins and decision making in the context of Industry 4.0. The use of simulation models and digital twins is manifold, from planning to virtual commission and real-time operational decision support. Cyber-physical systems integrate the real world and the virtual world to enable decision making in the age of Industry 4.0. For example, customer decisions and supply disruptions which directly influence manufacturing and logistics systems require immediate decisions. Thus, models must have the capability to support decision making in manufacturing as well as in internal and external logistics in real-time. Methods include discrete-event simulation, discrete-rate simulation, hybrid simulation, system dynamics simulation, the combination of simulation modeling with machine learning or optimization heuristics, prescriptive analytics, and adaptive systems. Furthermore, this minitrack addresses simulation education and simulation models used for education and training in manufacturing and logistics. Y1 - 2024 SN - 978-0-9981331-7-1 U6 - https://doi.org/10.24251/HICSS.2024.206 SP - 1647 EP - 1648 PB - ScholarSpace ER - TY - THES A1 - Eigenberger, Andreas T1 - Die Auswirkungen der mechanischen Kräfte eines innovativen Operationsverfahrens für die intraoperative Gewebezubereitung bei autologem Fetttransfer auf das Fettgewebe und dessen Stammzellen Y1 - 2024 SP - 235 Blätter CY - Regensburg ER - TY - JOUR A1 - Weindler, Jeremy A1 - Lehner, Hannes A1 - Eckstein, J. A1 - Dawoud, Belal T1 - Performance assessment of a green hydrogen-based household energy system supported by a battery storage at different resolutions of the electrical load profile JF - International Journal of Hydrogen Energy N2 - Hydrogen deems quite suitable for medium- and long-term energy storage of surplus renewable electricity. Nowadays, all-in-one solutions consisting of an electrolyzer, a compressor, pressurized hydrogen storage tanks, a fuel cell (FC) and the necessary peripheral components are available for single family houses. This work presents a comparative assessment of the system’s key performance indicators in a household system with three market available FCs with the nominal powers of 0.8, 1.4 and 7.8 kW. The design tool developed for the assessment of the hybrid energy system along with two energy management system configurations are introduced. An electrochemical and thermal model widely applied in the literature is used to model the FCs, which is validated against the available experimental data in the literature for all three FCs. The influence of the FCs’ nominal power, their power dynamic operation range, the use of a battery storage with different capacities and the load profile’s resolution have been technically assessed regarding the system’s self-sufficiency (SS), the FC’s efficiency, full-load operating hours, and number of on/off cycles. It turned out that, the system performance is strongly dependent on the nominal power of the FC and its power dynamic operation range. If no battery-storage is applied, the complete grid independence is not possible, and a high resolution of the load profile is indispensable in the assessment of the system design. A hybrid energy system comprising the 1.4 kW FC, a PV system of 10 kW peak power and a battery of 15 kW storage capacity showed a degree of SS of 98%. The number of the full-load operating hours and on/off cycles of that FC amount to 768 and 116 cycles, respectively. Such promising results are referred to the high dynamic operation range of the battery, and its high discharge power capacity, which makes it more suitable to cover a remarkably higher fraction of the load deficit, if compared to a system without a battery. KW - Hybrid energy storage KW - Battery KW - Hydrogen KW - Fuel cell KW - PV KW - Load profile resolution Y1 - 2025 U6 - https://doi.org/10.1016/j.ijhydene.2025.04.431 SN - 0360-3199 N1 - Corresponding author der OTH Regensburg: Dawoud, Belal VL - 144 SP - 30 EP - 41 PB - Elsevier ER - TY - JOUR A1 - Weindler, Jeremy A1 - Dawoud, Belal T1 - Experimental investigation of a small-scale continuous flow ohmic heating reactor for a highly effective conversion of renewable electricity surpluses into heat JF - Applied Thermal Engineering N2 - Sector coupling is expected to play a decisive role as a key technology to realize the energy transition towards green energy supply. This work introduces, therefore, a comprehensive experimental study on a new power-to-heat system based on the continuous-flow, ohmic heating principle, which aims at utilizing renewable electricity in green processes. The ohmic heating technology, which is widely applied in the food industry, has been adapted and evaluated for delivering heat and domestic hot water to a single-family house. The introduced prototype is designed to convert renewable electricity into heat in the power range between 1000 and 3000 W with a typical electrical household installation (230 V, 50 Hz and 16 A fuse). A dedicated test rig has been developed and a comprehensive experimental campaign has been carried out to investigate the performance of the introduced system under typical operating conditions of a single-family house. Both the conversion efficiency and the dynamics of the thermal response of the introduced system have been assessed. It turned out that, the temperature lift between the return and supply of the reactor, and consequently, the conversion efficiency of electrical into thermal energy, are independent on the return temperature, for a fixed value of the volume flow rate of the electrolyte solution. A remarkable steady-state conversion efficiency of 97.5% has been measured. In addition, the dynamic response of the ohmic heating system has been found to be strongly dependent on the desired temperature lift. By an implemented controller, 95% of the steady state temperature lift of 44.5 K can be realized in 50 s, which marks an exceptionally rapid thermal response. The obtained results pave the way towards a field test study of the developed technology in a real household installation as well as to extend the focus on new fields such as green chemical processes. KW - renewable energy KW - Ohmic-heating KW - Power-to-heat KW - Sector coupling KW - Energy surpluses Y1 - 2024 U6 - https://doi.org/10.1016/j.applthermaleng.2024.122401 SN - 1359-4311 N1 - Corresponding author der OTH Regensburg: Dawoud, Belal VL - 242 PB - Elsevier ER - TY - JOUR A1 - Sittl, Christopher A1 - Marburg, Steffen A1 - Deckers, Elke A1 - Wagner, Marcus T1 - Model order reduction for unbounded second-order vibroacoustic systems using infinite elements and Dirichlet-to-Neumann map JF - Computer Methods in Applied Mechanics and Engineering N2 - This work addresses the efficient numerical simulation of time-harmonic vibroacoustic problems in unbounded domains, with a focus on fluid-structure interaction. The underlying mathematical model is a second-order dynamical system arising from the coupling of structural and acoustic domains, incorporating material damping effects, relevant in structural acoustics and noise control applications. A central novelty of the proposed method is its unified computational framework that supports two distinct strategies for treating unbounded fluid domains: (1) non-local absorbing boundary conditions based on Dirichlet-to-Neumann map, and (2) infinite elements, which extend the computational domain rather than truncate it. Both approaches are integrated into a consistent formulation that enables flexible and accurate modeling of exterior wave propagation. To efficiently evaluate frequency-domain transfer functions, the method employs model order reduction using the Padé-via-Lanczos technique. While this algorithm typically targets first-order systems, the present approach uses a Schur complement strategy to reduce the second-order system in a way that maintains computational efficiency and storage requirements comparable to first-order formulations. Importantly, the framework seamlessly embeds both interior structural damping and the additional dissipation introduced by the acoustic-domain truncation into the model-order reduction process. The exterior acoustic field is represented via spherical harmonic expansions, with expansion coefficients computed from the reduced system. Numerical results demonstrate the method’s accuracy, efficiency, and scalability, making it well-suited for high-fidelity vibroacoustic analysis in unbounded domains. KW - Lanczos algorithm KW - Krylov-subspace projection KW - Dirichlet-to-Neumann map KW - Infinite elements KW - Padé approximation KW - Fluid-structure interaction KW - Acoustics KW - Spherical harmonics Y1 - 2026 U6 - https://doi.org/10.1016/j.cma.2026.118846 VL - 453 PB - Elsevier ER - TY - GEN A1 - Lehrer, Tobias A1 - Stocker, Philipp A1 - Duddeck, Fabian A1 - Wagner, Marcus T1 - Parametric CAD Models to Create an Infinite Number of Structural U-Shaped Sheet Metal Geometries [Data set] N2 - The U-Channel Software is a python package containing four parametric models of U-shaped Sheet metals. The parameters refer to geometric dimensions, angles, fillet radii. Using the models, one can generate an infinite number of U-shaped sheet metal geometries, e.g. as STEP files. The parametric models are inspired by real-world shapes. A feasibility check is provided to ensure plausiblity of the shapes. Further features of the code are creating images of the geometries and generating geometries and images in parallel. For more details, refer to the repository and associated publications. Y1 - 2024 U6 - https://doi.org/10.5281/ZENODO.14191374 N1 - Repository URL: https://github.com/ToLe814/uchannel Programming language: Python Development Status: Active ER - TY - THES A1 - Mühlbauer, Christian T1 - Entwicklung einer Methodik zur Bewertung und Optimierung des vibroakustischen Verhaltens von Kraftstoffeinspritzsystemen N2 - Die vorliegende Dissertation befasst sich mit der akustischen Analyse von Kraftstoffein-spritzsystemen und deren NVH-Optimierung mithilfe ansteuerungstechnischer Maßnahmen. Da sich der Körper- und Luftschall beim Betrieb des Verbrennungsmotors mit anderen, nicht untersuchungsrelevanten Geräuschkomponenten überlagert, ist im Vollmotorbetrieb eine diffe-renzierte komponentenbasierte Geräuschmessung nicht möglich. Deshalb wurde ein NVH-Sys-temprüfstand entwickelt, der eine isolierte akustische Vermessung von Einspritzsystemen im seriennahen Systemverbund ermöglicht. Die Betriebsparameter des Einspritzsystems wurden an einem Vollmotor in einem leerlaufna-hen Motorbetriebspunkt erfasst und mithilfe eines speziellen Entwicklungssteuergeräts auf den NVH-Systemprüfstand transferiert. Ausgehend von dem definierten Referenzbetriebspunkt wurden sowohl die Randbedingungen als auch die Ansteuerstrategie variiert und deren Einfluss auf das akustische Verhalten analysiert. Dabei zeigten primär der Raildruck und die Anzahl der Einspritzungen einen ausgeprägten Einfluss auf die betrachteten (psycho-)akustischen Parame-ter Schalldruckpegel, Lautheit, Schärfe und Impulshaltigkeit. Zur akustischen Optimierung der mechatronischen Komponenten wurden zum einen der An-steuerstrom reduziert und zum anderen ein Bremsimpuls am Ende der Ansteuerung implemen-tiert. Dadurch konnten die mechanischen Prellereignisse deutlich reduziert werden. Mithilfe eines Einspritzratenmessgeräts wurde allerdings nachgewiesen, dass sich die Optimierungs-maßnahmen insbesondere auf die Streuung der eingespritzten Kraftstoffmasse negativ auswir-ken und damit ein Zielkonflikt aus Geräuschqualität und Primärfunktionen entsteht. Als signi-fikanter Kipppunkt wurde bei den Injektoren der Übergang vom linearen Vollhub-Betrieb zum ballistischen Teilhub-Betrieb identifiziert. Aus diesem Grund wurde die elektrische Ansteue-rung unter der Voraussetzung des Injektor-Vollhub-Betriebs optimiert. Bei der Beurteilung des Einflusses der NVH-optimierten Ansteuerprofile auf die Robustheit der mechatronischen Komponenten wirkten sich eine niedrige Versorgungsspannung sowie eine kurze Ansteuerdauer der Injektoren besonders negativ auf die Streuung der eingespritzten Kraftstoffmasse aus. Vor allem in Verbindung mit der stromreduzierten Ansteuerung wurden die Injektoren nicht mehr zuverlässig und reproduzierbar im Voll-Hub geöffnet. Weiterhin wur-den durch die Bremspuls-Applikation injektorspezifische Abweichungen im Schließverhalten weiter verstärkt und erhöhten damit auch die Abweichungen der mittleren eingespritzten Kraft-stoffmasse zwischen den untersuchten Injektor-Exemplaren. Abschließend wurde die Übertragbarkeit des Systemverhaltens ermittelt, indem die Optimie-rungsmaßnahmen auf einen weiteren Versuchsträger ausgeweitet wurden. Dabei zeigte sich, dass die Maßnahmen zwar grundsätzlich übertragbar waren, aber die Parametrierung bezüglich Ansteuerstromreduzierung und Bremspuls-Applikation zum Teil stark angepasst werden mussten. N2 - The present dissertation deals with the acoustic analysis of fuel injection systems and their NVH optimization by means of control measures. Since the structure-borne and airborne sound dur-ing operation of the combustion engine is superimposed with other noise components that are not relevant for the analysis, a differentiated component-based noise measurement is not possi-ble in full engine operation. For this reason, an NVH system test bench has been developed that enables isolated acoustic measurements of fuel injection systems in a near-series system com-pound. The operating parameters of the injection system were recorded on a full engine at an engine operating point close to idle and transferred to the NVH system test bench by means of a special development control unit. Beginning from the defined reference operating point, both the boundary conditions and the control strategy were varied and their influence on the acoustic behavior analyzed. Primarily, the rail pressure and the number of injections had a distinct in-fluence on the (psycho-)acoustic parameters considered: sound pressure level, loudness, sharp-ness and impulsiveness. To optimize the mechatronic components acoustically, the control current was reduced and a braking pulse was implemented at the end of the control. This significantly reduced the me-chanical bounce events. However, using an injection rate measurement device revealed that the optimization measures had a particularly negative effect on the scattering of the injected fuel mass, resulting in a trade-off between noise quality and performance. To this, the shift from linear full-stroke operation to ballistic partial-stroke operation of the injectors was identified as a significant tipping point. Therefore, the electrical control was optimized under the condition of injector full stroke operation. Considering the influence of the NVH optimized control profiles on the robustness of the mech-atronic components, particularly a low supply voltage and a short control duration of the injec-tors showed a negative effect on the scattering of the injected fuel mass. Especially in combi-nation with the reduced control current, the injectors were no longer able to open reliably and reproducibly in the full stroke. Additionally, the brake pulse application further increased in-jector-specific deviations in the closing behavior and thus increased the deviations of the mean injected fuel mass between the injector samples investigated. Finally, the transferability of the system behavior was determined by extending the optimization measures to another demonstrator. It turned out that the measures were generally transferable, but the parameterization with regard to control current reduction and brake pulse application had to be adapted considerably in some cases. KW - Brennstoffe KW - Explosivstoffe KW - Kraftstoffe KW - Technik der Verkehrsmittel Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:ma9:1-1981185920-1115312 ER - TY - THES A1 - Schwanzer, Peter T1 - Experimentelle Untersuchungen zur On-Board Überwachung von Partikelfiltern für den Einsatz an direkteinspritzenden Benzinmotoren N2 - This thesis deals with the development of a methodology for an improved on-board diagnosis of particulate filters in vehicles with gasoline direct injection (GDI) technology with regard to future emission legislations. In order to comply with statutory particle number limits, particulate filters are used in the exhaust gas aftertreatment for GDI-engines. The currently applied method for diagnostic purposes, a differential pressure sensor, will not be suitable for future legislations. Therefore, an on-board strategy with real-time ability shall be developed. To achieve this, the application of novel sensor concepts has been investigated, namely electrostatic soot sensors (ePM sensor) and radio frequency antennas (RF sensor). Due to the results of the ePM-sensors, no methodology for an on-board diagnosis based on an ePM sensor concept was made. The RF sensor showed varying sensitivities for different soot and different quantities of volatile components in the filter element. The analysis of the oxidation processes showed that the regeneration of the filter element is detected by the RF sensor. Furthermore, the stored amount of ash could be captured. Due to these findings, a concept for an improved on-board diagnosis strategy by means of an RF sensor concept was developed. In the course of the work it turned out that a combined sensor concept consisting of a differential pressure sensor and a RF sensor is most suitable. In a validation process, this sensor concept showed sufficient results concerning the detection capability of soot and ash loads as well as of the degree of damage of particulate filters. Especially for small amounts of ash, this sensor concept showed specific advantage. Also, the determination of the current amount of soot in the filter element proved to be suitable. Regarding the detection of damages, the sensor concept convinces through a higher sensitivity. KW - GDI KW - GPF KW - On-Board-Monitoring Y1 - 2022 SN - 978-3-8439-5101-2 PB - Verlag Dr. Hut CY - München ER -