TY - CHAP A1 - Xue, Lufeng A1 - Paredes, Marcelo A1 - Nonn, Aida A1 - Wierzbicki, Tomasz T1 - Modeling of Crack Propagation in Defective X100 Line Pipes T2 - ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering: August 3-7, 2020, virtual, online N2 - A comprehensive experimental program is carried out to determine material parameters for fracture initiation and propagation in X100 pipeline steels. The quadratic Hill’48 yield function along with an isotropic hardening are used to describe plastic flow at large deformation and a phenomenological fracture criterion to predict fracture initiation. Fracture mechanics SENT specimens are used to calibrate post-initiation softening parameters necessary for ductile crack propagation in thick components. Once the material model parameters set is complete a final comparison is conducted with ring expansion test on same material. KW - Berg KW - Bruchmechanik KW - Pipeline KW - plastisches Fließen KW - Rissausbreitung KW - Versuchsprogramm KW - Werkstoffmodell KW - Werkstoffparameter Y1 - 2020 SN - 978-0-7918-8434-8 U6 - https://doi.org/10.1115/OMAE2020-18048 PB - American Society of Mechanical Engineers CY - New York ER - TY - JOUR A1 - Wiesent, Lisa A1 - Stocker, Felix A1 - Nonn, Aida T1 - Investigating the influence of geometric parameters on the deformation of laser powder bed fused stents using low-fidelity thermo-mechanical analysis JF - Materialia N2 - Maintaining dimensional accuracy is a major challenge of laser powder bed fusion (L-PBF) preventing its application for more complex and filigree L-PBF structures in industrial practice. Previous studies have shown that residual stresses and distortion of benchmark L-PBF components may be predicted by sequential thermo-mechanical analyses. However, the reliability of these analyses for more complex structures must be critically questioned, as comprehensive validation and sensitivity analyses are scarce. In this paper, we present a calibrated and validated low-fidelity sequential thermo-mechanical finite element analysis (FEA) of a tubular L-PBF lattice structure, i.e., an aortic stent, where pronounced local deformation is expected. As a first step, the finite element model was extensively calibrated using experimental data to ensure reproducibility of the simulation results. Thereupon, geometric features critical to the distortion of L-PBF lattice structures and measures to compensate for the distortion, such as inversion of the distorted L-PBF structure, were investigated. It was found that the distortion of the L-PBF lattice structures can be reduced, but not completely prevented, by increasing the strut angles, increasing the strut thickness, and decreasing the transition radius in the area of merging struts. FEA-based inversion of the numerically predicted deformed structure minimized distortion, resulting in the L-PBF aortic stent approximating the intended CAD geometry even with a small strut thickness. This work shows that low-fidelity sequential thermo-mechanical FEA can be used not only for the analysis and deformation compensation of reference structures, but also for the analysis of more complex filigree structures with pronounced local deformation. Y1 - 2023 U6 - https://doi.org/10.1016/j.mtla.2023.101774 VL - 28 PB - Elsevier ER - TY - JOUR A1 - Nonn, Aida A1 - Kiss, Bálint A1 - Pezeshkian, Weria A1 - Tancogne-Dejean, Thomas A1 - Cerrone, Albert R. A1 - Kellermayer, Miklos A1 - Bai, Yuanli A1 - Li, Wei A1 - Wierzbicki, Tomasz T1 - Inferring mechanical properties of the SARS-CoV-2 virus particle with nano-indentation tests and numerical simulations JF - Journal of the mechanical behavior of biomedical materials N2 - The pandemic caused by the SARS-CoV-2 virus has claimed more than 6.5 million lives worldwide. This global challenge has led to accelerated development of highly effective vaccines tied to their ability to elicit a sustained immune response. While numerous studies have focused primarily on the spike (S) protein, less is known about the interior of the virus. Here we propose a methodology that combines several experimental and simulation techniques to elucidate the internal structure and mechanical properties of the SARS-CoV-2 virus. The mechanical response of the virus was analyzed by nanoindentation tests using a novel flat indenter and evaluated in comparison to a conventional sharp tip indentation. The elastic properties of the viral membrane were estimated by analytical solutions, molecular dynamics (MD) simulations on a membrane patch and by a 3D Finite Element (FE)-beam model of the virion's spike protein and membrane molecular structure. The FE-based inverse engineering approach provided a reasonable reproduction of the mechanical response of the virus from the sharp tip indentation and was successfully verified against the flat tip indentation results. The elastic modulus of the viral membrane was estimated in the range of 7-20 MPa. MD simulations showed that the presence of proteins significantly reduces the fracture strength of the membrane patch. However, FE simulations revealed an overall high fracture strength of the virus, with a mechanical behavior similar to the highly ductile behavior of engineering metallic materials. The failure mechanics of the membrane during sharp tip indentation includes progressive damage combined with localized collapse of the membrane due to severe bending. Furthermore, the results support the hypothesis of a close association of the long membrane proteins (M) with membrane-bound hexagonally packed ribonucleoproteins (RNPs). Beyond improved understanding of coronavirus structure, the present findings offer a knowledge base for the development of novel prevention and treatment methods that are independent of the immune system. Y1 - 2023 U6 - https://doi.org/10.1016/j.jmbbm.2023.106153 SN - 1751-6161 VL - 148 PB - Elsevier ER - TY - JOUR A1 - Cerrone, Albert R. A1 - Nonn, Aida A1 - Hochhalter, Jacob D. A1 - Bomarito, Geoffrey F. A1 - Warner, J. E. A1 - Carter, Bruce J. T1 - Predicting failure of the Second Sandia Fracture Challenge geometry with a real-world, time constrained, over-the-counter methodology JF - International Journal of Fracture N2 - An over-the-counter methodology to predict fracture initiation and propagation in the challenge specimen of the Second Sandia Fracture Challenge is detailed herein. This pragmatic approach mimics that of an engineer subjected to real-world time constraints and unquantified uncertainty. First, during the blind prediction phase of the challenge, flow and failure locus curves were calibrated for Ti–6Al–4V with provided tensile and shear test data for slow (0.0254 mm/s) and fast (25.4 mm/s) loading rates. Thereafter, these models were applied to a 3D finite-element mesh of the non-standardized challenge geometry with nominal dimensions to predict, among other items, crack path and specimen response. After the blind predictions were submitted to Sandia National Labs, they were improved upon by addressing anisotropic yielding, damage initiation under shear dominance, and boundary condition selection. KW - Ti–6Al–4V KW - Failure locus curve KW - Sandia Fracture Challenge KW - Anisotropic yielding Y1 - 2016 U6 - https://doi.org/10.1007/s10704-016-0086-x VL - 198 IS - 1-2 SP - 117 EP - 126 ER - TY - CHAP A1 - Romano, Marco A1 - Hoinkes, Carl J. J. A1 - Ehrlich, Ingo A1 - Höcherl, Johannes A1 - Gebbeken, Norbert ED - Meran, C. T1 - Influence of the impactor on the experimentally determined energy dissipation properties of fiber-reinforced plastics with hybrid layups under high velocity impact loads T2 - Proceeding of the 15th International Materials Symposium (IMSP´2014), Pamukkale University (Denizli, Turkey), 15./17. October 2014 Y1 - 2014 SP - 650 EP - 664 ER - TY - CHAP A1 - Hoinkes, Carl J. J. A1 - Romano, Marco A1 - Ehrlich, Ingo A1 - Höcherl, Johannes A1 - Gebbeken, Norbert ED - Ziemann, Olaf ED - Mottok, Jürgen ED - Pforr, Johannes T1 - Investigation of fibre reinforced plastics with monolithic and hybrid stacking sequences under high-velocity impact loads T2 - Applied Research Conference 2014 - ARC 2014, 5th July 2014, Ingolstadt Y1 - 2014 PB - Shaker CY - Aachen ER - TY - JOUR A1 - Cerrone, Albert R. A1 - Wawrzynek, Paul A1 - Nonn, Aida A1 - Paulino, Glaucio H. A1 - Ingraffea, Anthony R. T1 - Implementation and verification of the Park–Paulino–Roesler cohesive zone model in 3D JF - Engineering Fracture Mechanics N2 - The Park–Paulino–Roesler (PPR) potential-based model is a cohesive constitutive model formulated to be consistent under a high degree of mode-mixity. Herein, the PPR’s generalization to three-dimensions is detailed, its implementation in a finite element framework is discussed, and its use in single-core and high performance computing (HPC) applications is demonstrated. The PPR model is shown to be an effective constitutive model to account for crack nucleation and propagation in a variety of applications including adhesives, composites, linepipe steel, and microstructures. KW - Cohesive zone modeling KW - Cohesive element KW - Intergranular fracture KW - Finite element analysis KW - PPR potential-based model Y1 - 2014 U6 - https://doi.org/10.1016/j.engfracmech.2014.03.010 VL - 120 SP - 26 EP - 42 ER - TY - CHAP A1 - Eisenried, Michael A1 - Romano, Marco A1 - Jungbauer, Bastian A1 - Ehrlich, Ingo A1 - Gebbeken, Norbert ED - Ziemann, Olaf ED - Bogner, Werner ED - Mottok, Jürgen T1 - Influence of parameters of the production process on the material quality of unidirectionally reinforced prepregs T2 - Applied Research Conference 2013, ARC 2013 ; 17th and 18th October 2013, Deggendorf Y1 - 2013 SP - 70 EP - 75 PB - Shaker CY - Aachen ER - TY - CHAP A1 - Lindner, Matthias A1 - Berndt, Dominik A1 - Tschurtschenthal, Karl A1 - Ehrlich, Ingo A1 - Jungbauer, Bastian A1 - Schreiner, Rupert A1 - Pipa, Andrei V. A1 - Hink, Rüdiger A1 - Foest, Rüdiger A1 - Brandenburg, Ronny A1 - Neuwirth, Daniel A1 - Karpen, Norbert A1 - Bonaccurso, Elmar A1 - Weichwald, Robert A1 - Max, Alexander A1 - Caspari, Ralf T1 - Aircraft Icing Mitigation by DBD-based Micro Plasma Actuators T2 - AIAA AVIATION 2020 FORUM: June 15-19, 2020 N2 - We present the application of plasma actuators as a technology for ice prevention at airfoils. The miniaturized dielectric barrier discharge (DBD) plasma actuators (PA) were fabricated by means of microelectromechanical systems (MEMS). We elucidate how to make the actuator samples scalable and applicable to any desired shape by the use of flexible inorganic zirconia substrates. For this purpose, we applied our developed embedding method to integrate the micro actuators in modern carbon/glass fiber reinforced polymer (CFRP/GFRP) materials. Next, the embedded actuator samples were mounted on a mechanical air profile-like fixture and placed in the icing wind tunnel iCORE. The samples were tested in rime ice conditions at temperatures of -15 to -20° C and air speeds up to 30 m/s. Unlike other groups we used a thin film zirconia substrate as dielectric for the plasma actuator. Due to the low substrate thickness of just 150 µm, an operating voltage of 2 kVRMS is already sufficient enough for a stable plasma formation. The experiments show that the operated actuator was able to prevent the ice formation and first indications of a De-icing function were also found. Hence, we show that it is feasible to realize an anti-icing system with zirconia-based plasma actuators operated at lower voltages compared to conventional ones. Y1 - 2020 U6 - https://doi.org/10.2514/6.2020-3243 ER - TY - CHAP A1 - Lindner, Matthias A1 - Berndt, Dominik A1 - Jungbauer, Bastian A1 - Ehrlich, Ingo A1 - Schreiner, Rupert A1 - Pipa, Andrei V. A1 - Hink, Rüdiger A1 - Foest, Rüdiger A1 - Brandenburg, Ronny A1 - Max, Alexander A1 - Caspari, Ralf T1 - Fabrication, surface integration and testing of miniaturized dielectric barrier discharge plasma actuators for active flow control applications T2 - AIAA Aviation 2019 Forum, 17-21 June 2019, Dallas, Texas Y1 - 2019 U6 - https://doi.org/10.2514/6.2019-2998 ER - TY - CHAP A1 - Niedernhuber, Michal A1 - Ehrlich, Ingo A1 - Holtmannspötter, Jens ED - Ziemann, Olaf ED - Mottok, Jürgen ED - Pforr, Johannes T1 - Fiber-Oriented Repair of Fiber Reinforced Plastics: Investigations on Tensile Specimens T2 - 4th Applied Research Conference - ARC 2014, 5th July 2014, Ingolstadt Y1 - 2014 SP - 298 EP - 302 PB - Shaker CY - Aachen ER - TY - CHAP A1 - Pongratz, Christian A1 - Ehrlich, Ingo ED - Mottok, Jürgen ED - Reichenberger, Marcus ED - Stolle, Reinhard T1 - Structural Dynamic Analysis of Thin Composite Plates Using Noncontact Measurement and Excitation T2 - Applied Research Conference 2016 - ARC 2016, Augsburg, 24 June 2016 Y1 - 2016 SN - 978-3-86460-494-2 SP - 351 EP - 358 PB - Pro Business Verlag CY - Berlin ER - TY - RPRT A1 - Pongratz, Christian A1 - Ehrlich, Ingo ED - Baier, Wolfgang T1 - DampSIM: Lebensdauerüberwachung von faserverstärkten Kunststoffen auf Basis der strukurdynamischen Werkstoffdämpfung T2 - Forschungsbericht 2017 / Ostbayerische Technische Hochschule Regensburg Y1 - 2017 UR - https://doi.org/10.35096/othr/pub-1383 SN - 978-3-9818209-3-5 SP - 62 EP - 63 ER - TY - RPRT A1 - Pongratz, Christian A1 - Ehrlich, Ingo ED - Baier, Wolfgang T1 - High-End-Strukturen für den Leichtbau – mit faserverstärktem 3D-Druck T2 - Forschung 2018 / Ostbayerische Technische Hochschule Regensburg Y1 - 2018 UR - https://doi.org/10.35096/othr/pub-1382 SN - 978-3-9818209-4-2 SP - 64 EP - 65 ER - TY - GEN A1 - Judenmann, Anna A1 - Pongratz, Christian A1 - Ehrlich, Ingo A1 - Höfer, Philipp A1 - Holtmannspötter, Jens T1 - Additive Fertigung von endlosfaserverstärkten Kunststoffstrukturen T2 - Münchner Leichtbauseminar 2022, 26. October 2022, 16. November 2022, 30 November 2022, Munich/Neubiberg/Garching N2 - Additive Fertigung hat sich in zahlreichen industriellen Anwendungen etabliert und bildet eine wichtige Schlüsseltechnologie. Im Gegensatz zu metallischen Werkstoffen, haben additiv gefertigte Bauteile aus Kunststoffen geringere Festigkeit und Steifigkeit, sodass sich ihre Verwendung als lasttragende Strukturen schwierig gestaltet. Insbesondere der Einsatz von endlosen Verstärkungsfasern kann die mechanischen Eigenschaften additiv gefertigter Strukturen signifikant verbessern und die Fertigung hochbelastbarer Faserverbundstrukturen im 3D-Druckverfahren ermöglichen. Daher gilt es aktuell notwendige Anlagen und Prozessketten für den Fertigungsprozess aber auch Vorgehensweisen für die belastungsoptimierte Auslegung der Faserverläufe innerhalb des Bauteils zu entwickeln, um so das Themengebiet „Endlosfaserverstärkter 3D-Druck“ weiter voranzutreiben. Für mehr räumliche Freiheit bei der Positionierung der Druckbahnen können industrieroboterbasierte Systeme eingesetzt werden, um so das Potenzial gerichteter Bauweise von Faserverbundstrukturen auch im additiven Fertigungsprozess vollumfänglich ausschöpfen zu können. Dabei ermöglicht ihr Einsatz auch eine räumliche Ablage der Faserverstärkung, wobei für die Materialablage ein geeigneter 3D-Druckkopf erforderlich ist. Für die Implementierung der Faserverstärkung ist zudem eine dem Lastfall entsprechende Auslegung des Bauteils sowie die Ermittlung einer sinnvollen Faserpositionierung innerhalb des Bauteils erforderlich, wobei unterschiedliche Variablen aus den Bereichen Material, Struktur und Fertigungsprozess berücksichtigt werden müssen. Im Rahmen des Vortrages werden die Herausforderungen der Technologieentwicklung des endlosfaserverstärkten 3D-Drucks aufgegriffen sowie auf eine belastungsorientierte Faserpositionierung näher eingegangen. Aktuelle Erkenntnisse werden diskutiert sowie eine Entwurfsmethodik für die Prozesspfadgenerierung vorgeschlagen. KW - additive manufacturing KW - continuous fiber KW - composites KW - toolpath Y1 - 2022 ER - TY - JOUR A1 - Niedernhuber, Michal A1 - Holtmannspötter, Jens A1 - Ehrlich, Ingo T1 - Fiber-oriented repair geometries for composite materials JF - Composites, Part B N2 - In this paper, the idea of fiber-oriented repair geometries for carbon fiber reinforced plastics (CFRP) is investigated. It considers the differing mechanical properties of unidirectional fiber reinforced material by excluding overlapping regions perpendicular to the fiber direction of the particular layer. A mechanical and numerical comparison of tensile strength of stepped joints with continuous step lengths per ply and stepped joints with reduced step lengths in plies with fiber orientation differing from load direction is performed. Finite element simulations show similar shear stresses. Mechanical tests of CFRP laminates with stepped joints show no significant deviation in tensile strength, in spite of a joint length reduction of nearly 40%. This leads to the possibility of a significant reduction of repair area. Y1 - 2016 U6 - https://doi.org/10.1016/j.compositesb.2016.03.027 VL - 94 SP - 327 EP - 337 ER - TY - JOUR A1 - Pongratz, Christian A1 - Schlamp, Matthias A1 - Jungbauer, Bastian A1 - Ehrlich, Ingo A1 - Petratos, P. A1 - Mourtos, N. T1 - Detection of Delamination Damages in Thin Composite Plates using Noncontact Measurement of Structural Dynamic Behavior JF - Athens Journal of Technology & Engineering Y1 - 2016 U6 - https://doi.org/10.30958/AJTE.3-4-3 VL - 3 IS - 4 SP - 315 EP - 331 ER - TY - JOUR A1 - Xue, Lufeng A1 - Keim, Vincent A1 - Paredes, Marcelo A1 - Nonn, Aida A1 - Wierzbicki, Tomasz T1 - Anisotropic effects on crack propagation in pressurized line pipes under running ductile fracture scenarios JF - Engineering fracture mechanics N2 - The current analyses present results of running ductile fracture propagation in high strength X100 line pipe steels under the influence of anisotropy. Mechanical anisotropy is commonly available in pipe products as a result of the manufacturing process, especially, those subjected to hot/cold-worked deformation. The outcomes of the present analyses show that its effect on the behavior of running ductile fracture in cracked pipes undergoing depressurization is meaningful. For instance, the Crack-Tip Opening Angle (CTOA) not only exhibits a strong dependence to the pipe's diameter size, but also to the material's anisotropy nature when compared to a hypothetical isotropic material. Moreover, laboratory scale tests such as those performed on Battelle Drop Weight Tear (BDWT) samples provide useful information about initiation of ductile crack propagation when the anisotropy features are taken into account in the material description. KW - BEHAVIOR KW - Fracture anisotropy KW - INITIATION KW - MODEL KW - Non-associated flow rule KW - PREDICTION KW - Rate dependent MMC Model KW - Running ductile fracture KW - STATE KW - STEEL KW - STRAIN-RATE KW - TOUGHNESS Y1 - 2021 U6 - https://doi.org/10.1016/j.engfracmech.2021.107748 VL - 249 PB - Elsevier 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 - 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 - 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 - 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 -