@article{NiedernhuberHoltmannspoetterEhrlich, author = {Niedernhuber, Michal and Holtmannsp{\"o}tter, Jens and Ehrlich, Ingo}, title = {Fiber-oriented repair geometries for composite materials}, series = {Composites, Part B}, volume = {94}, journal = {Composites, Part B}, doi = {10.1016/j.compositesb.2016.03.027}, pages = {327 -- 337}, abstract = {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.}, language = {en} } @article{RomanoHoinkesEhrlichetal., author = {Romano, Marco and Hoinkes, Carl J. J. and Ehrlich, Ingo and H{\"o}cherl, Johannes and Gebbeken, Norbert}, title = {Experimental investigation of energy dissipation properties of fibre reinforced plastics with hybrid layups under high-velocity impact loads}, series = {Journal of Achievements in Materials and Manufacturing Engineering (JAMME)}, volume = {64}, journal = {Journal of Achievements in Materials and Manufacturing Engineering (JAMME)}, number = {1}, pages = {14 -- 20}, abstract = {Purpose: The present work deals with the experimental investigation concerning the energy dissipation capacity of different kinds of reinforcement fibres in monolithic and hybrid layups under high velocity impact loads. The investigated kinds of fibres are carbon, glass and basalt. Design/methodology/approach: The test panels have been impregnated with thermoset resin. Curing was done by autoclave processing. In order to obtain comparable fibre volume contents of approx. 60 \% in the different layups (monolithic and hybrid without and with separating layer), curing cycles adapted to the type of layup have been identified. The resulting fibre volume content of the test panels has been determined both by weighing and experimentally by chemical extraction and calcination. The impact load was applied by an instrumented experimental setup. Thereby both commercially available bullets and bearing balls accelerated with weighted propellant in a sabot have been used as impactors. The measured values are the velocities of the bearing balls as the impactor before and after penetration of the test panels. Findings: In both cases the results show the energy dissipation capacity of each single kind of fibre in case of the monolithic layups as well as the enhanced properties of the hybrid stacked layups without and with the separating layer as a core material. Typical failure modes on the impact surface and on the outlet areas are identified. Research limitations/implications: The influence of the respective kind of impactors, namely bullets and bearing balls, on the evaluated results is identified. Thereby the bearing balls exhibited a higher degree of reproducibility due to several reasons. Originality/value: Fibre reinforced plastics with hybrid stacking sequences can be used as load-bearing structures and at the same time as safety structures for passengers in automotive or aerospace applications. Moreover, with the hybrid stacked composites lightweight concepts can efficiently be realized regarding energy saving issues.}, language = {en} } @article{RomanoEhrlichGebbeken, author = {Romano, Marco and Ehrlich, Ingo and Gebbeken, Norbert}, title = {Structural mechanic material damping in fabric reinforced composites}, series = {Archives of Materials Science and Engineering (ArchivesMSE)}, volume = {88}, journal = {Archives of Materials Science and Engineering (ArchivesMSE)}, number = {1}, doi = {10.5604/01.3001.0010.7747}, pages = {12 -- 41}, abstract = {Purpose: A review regarding the acting mechanisms of structural dynamic material damping in fabric reinforced composites is presented. Design/methodology/approach: Mechanical acting principles identified by different investigations are considered. Aspects of the determination and calculation of structural mechanical material properties of fabric reinforced composites are described. Approaches intending the description and classification of ondulations in fabrics reinforced single layers are demonstrated. Findings: The mesomechanic geometry of fabrics is not considered sufficiently by relatively simple homogenization approaches. Yet, it significantly affects its structural dynamic material properties, especially the dynamic ones. Research limitations/implications: In each case the different damping mechanisms act coupled and occur at the same time. Therefore a separation procedure is required in any case. Practical implications: Against the background of the comparison and remarks of the presented papers a reasonable further procedure is recommended. Thereby, FE-calculations with a parametrical variation of the mesomechanic geometry in order to identify kinematic correlations due to geometric constraints are suggested. Originality/value: The idea of the representation of the geometric conditions in terms of a degree of ondulation is described. Such a non-dimensional specific value representing the intensity of the ondulation would enable the comparability of the results of different kinds of investigations.}, language = {en} } @article{RomanoEhrlichGebbeken, author = {Romano, Marco and Ehrlich, Ingo and Gebbeken, Norbert}, title = {Parametric characterization of a mesomechanic kinematic in plain and twill weave 2/2 reinforced composites by FE-calculations}, series = {Archives of Materials Science and Engineering (ArchivesMSE)}, volume = {97}, journal = {Archives of Materials Science and Engineering (ArchivesMSE)}, number = {1-2}, publisher = {Index Copernicus}, issn = {1897-2764}, doi = {10.5604/01.3001.0013.2869}, pages = {20 -- 38}, abstract = {Purpose: A parametric characterization of a mesomechanic kinematic caused by ondulation in fabric reinforced composites is investigated by numerical investigations. Design/methodology/approach: Due to the definition of plain representative sequences of balanced plain-weave and twill-weave 2/2 fabric reinforced single layers based on sines the variable geometric parameters are the amplitude and the length of the ondulation. Findings: The mesomechanic kinematic can be observed in the FE analyses for both kinds of fabric constructions. Research limitations/implications: The FE analyses consider elasticity and contraction due to Poisson effects, respectively, of the model under selected longitudinal strains. Practical implications: The results are evaluated at relevant positions on the centre-line of the ondulated warp-yarn of the plain representative model. A direct and linear coupling in case of the transversal kinematic behaviour, and thereby a corresponding definite reduction of the evaluated longitudinal strains in terms of the difference of the applied and determined longitudinal strains is identified. Originality/value: Both characteristic purely kinematic reactions due to geometric constraints directly depend on the introduced degree of ondulation. This non-dimensional parameter relates amplitude and length of one complete ondulation, and thus represents the intensity of the ondulation of the respective fabric construction.}, language = {en} } @article{RomanoEhrlichGebbeken, author = {Romano, Marco and Ehrlich, Ingo and Gebbeken, Norbert}, title = {Parametric characterization of a mesomechanic kinematic caused by ondulation in fabric reinforced composites: analytical and numerical investigations}, series = {Frattura ed Integrit{\`a} Strutturale (Fracture and Structural Integrity)}, volume = {11}, journal = {Frattura ed Integrit{\`a} Strutturale (Fracture and Structural Integrity)}, number = {39}, doi = {10.3221/IGF-ESIS.39.22}, pages = {226 -- 247}, abstract = {A parametric characterization of a mesomechanic kinematic caused by ondulation in fabric reinforced composites is investigated by analytical and numerical investigations. Due to the definition of plain representative sequences of balanced plain-weave fabric reinforced single layers based on sines the variable geometric parameters are the amplitude and the length of the ondulation. The mesomechanic kinematic can be observed in both the analytic model and the FE-analyses. The analytic model yields hyperbolic correlations due to the strongly simplifying presumptions that neglect elasticity. In contrast the FE-analyses yield linear correlations in much smaller amounts due to the consideration of elastic parts, yet distinctly.}, language = {en} } @article{RomanoHoinkesEhrlichetal., author = {Romano, Marco and Hoinkes, Carl J. J. and Ehrlich, Ingo and H{\"o}cherl, Johannes and Gebbeken, Norbert}, title = {Experimental investigation of fibre reinforced plastics with hybrid layups under high-velocity impact loads}, series = {Frattura ed Integrit{\`a} Strutturale (Fracture and Structural Integrity)}, volume = {8}, journal = {Frattura ed Integrit{\`a} Strutturale (Fracture and Structural Integrity)}, number = {29}, doi = {10.3221/IGF-ESIS.29.34}, pages = {384 -- 398}, abstract = {This paper deals with experimental investigations concerning energy dissipation capacity of different kinds of reinforcement fibres in monolithic and hybrid layups under high-velocity impact loads. The investigated kinds of fibres are carbon, glass and basalt fibres. Therefore test panels, using the same thermoset resin, were built up and cured by autoclave processing. The fibre volume content of the test panels has been determined. Furthermore the influence of a separating layer at selected positions in the hybrid stacked panels was investigated. The results show the influence and the energy dissipation capacity of each single kind of fibre and the enhanced properties for the hybrid layups by hybrid stacking sequences and the use of a separating core material.}, language = {en} } @inproceedings{NonnErdelenPepplerKalwa, author = {Nonn, Aida and Erdelen-Peppler, Marion and Kalwa, Christoph}, title = {Numerical and experimental investigation of the influence of HAZ on the fracture behavior of longitudinal welded linepipes}, series = {18th European Conference on Fracture, Fracture of Materials and Structures from Micro to Macro Scale, Dresden, Germany}, booktitle = {18th European Conference on Fracture, Fracture of Materials and Structures from Micro to Macro Scale, Dresden, Germany}, abstract = {The present paper deals with the influence of heat affected zone (henceforth HAZ) on the fracture performance of longitudinal welded linepipes in dependence on constraint level. It has been shown that toughness values of HAZ obtained from standard fracture mechanics tests lead to uneconomic linepipe design for two reasons. The first reason is that laboratory specimens with higher constraint level generally exhibit lower fracture resistance compared to flawed linepipes. The second one has to do with a higher probability of cleavage failure occurrence in the laboratory specimen than in the linepipes due to larger areas of lower toughness (so called local brittle zones (LBZ)) intersected by crack front. In recent years numerous studies have been initiated with the objective to quantify the constraint level and thus to allow for less conservative linepipe safety assessment by applying constraint corrected toughness values. However, the main focus of these studies has hitherto been on the homogeneous materials, failing to account for the possible effects of different microstructures within the heterogeneous HAZ. This paper seeks to close this gap by reporting on results from tests on fracture mechanics specimens of a high strength X80 steel, i.e. SENB and SENT specimens as well as results from ring expansion tests. Both, deep and shallow cracks are inserted in the fracture mechanics specimens and rings targeting the fusion line (FL). By varying the initial crack size and sample type, different constraint levels are achieved and subsequently quantified using numerical methods. Besides constraint observations, post metallographic analyses are performed to identify exact HAZ microstructure involved at the crack tip. Finally, the influence of HAZ properties, flaw size and geometry on the failure behaviour of the linepipes has been demonstrated and assessed. Based on the combination of the results from constraint studies and the post metallographic analyses, the methodology is proposed which enables simple quantitative prediction of toughness values for safe and economic design of linepipes with flaws located in HAZ.}, language = {en} } @inproceedings{KarbasianGrossWeegeNonnetal., author = {Karbasian, H. and Groß-Weege, J. and Nonn, Aida and Zimmermann, S. and Kalwa, Christoph}, title = {Assessment of collapse resistance of UOE pipes - comparison of full-scale and ring collapse tests}, series = {Proceedings of the 10th International Pipeline Conference 2014 (IPC 2014), September 29 - October 3, 2014, Calgary, Alberta, Canada}, booktitle = {Proceedings of the 10th International Pipeline Conference 2014 (IPC 2014), September 29 - October 3, 2014, Calgary, Alberta, Canada}, language = {en} } @techreport{PutzerRasmussenEhrlichetal., author = {Putzer, Michael and Rasmussen, John and Ehrlich, Ingo and Gebbeken, Norbert and Dendorfer, Sebastian}, title = {Muskuloskelettale Simulation zur Untersuchung des Einflusses geometrischer Parameter der Wirbelk{\"o}rper auf die Belastung der Lendenwirbels{\"a}ule}, series = {Forschungsbericht 2013 / Ostbayerische Technische Hochschule Regensburg}, journal = {Forschungsbericht 2013 / Ostbayerische Technische Hochschule Regensburg}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, pages = {60 -- 61}, language = {de} } @techreport{PongratzEhrlich, author = {Pongratz, Christian and Ehrlich, Ingo}, title = {DampSIM: Lebensdauer{\"u}berwachung von faserverst{\"a}rkten Kunststoffen auf Basis der strukurdynamischen Werkstoffd{\"a}mpfung}, series = {Forschungsbericht 2017 / Ostbayerische Technische Hochschule Regensburg}, journal = {Forschungsbericht 2017 / Ostbayerische Technische Hochschule Regensburg}, editor = {Baier, Wolfgang}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-9818209-3-5}, pages = {62 -- 63}, language = {de} } @techreport{PongratzEhrlich, author = {Pongratz, Christian and Ehrlich, Ingo}, title = {High-End-Strukturen f{\"u}r den Leichtbau - mit faserverst{\"a}rktem 3D-Druck}, series = {Forschung 2018 / Ostbayerische Technische Hochschule Regensburg}, journal = {Forschung 2018 / Ostbayerische Technische Hochschule Regensburg}, editor = {Baier, Wolfgang}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-9818209-4-2}, pages = {64 -- 65}, language = {de} } @article{BohmannSchlampEhrlich, author = {Bohmann, T. and Schlamp, Matthias and Ehrlich, Ingo}, title = {Acoustic emission of material damages in glass fibre-reinforced plastics}, series = {Composites Part B: Engineering}, volume = {155}, journal = {Composites Part B: Engineering}, number = {December}, publisher = {Elsevier}, doi = {10.1016/j.compositesb.2018.09.018}, pages = {444 -- 451}, abstract = {The aim of this study is to compare two different standardized testing procedures, tensile testing and Mode-I double cantilever beam (DCB) testing, to evaluate a possible correlation between the dominant failure in glass fibre-reinforced plastics and their according acoustic emissions (AE). AE is processed by using a burst collection of all recorded transient signals and is further analysed with the k-means clustering algorithm. To generate damage related AE, a series of experiments for tensile testing and Mode-I DCB testing is performed on 16-layer glass fibre/epoxy specimens with a cross-ply lay-up for tensile and an unidirectional lay-up for Mode-I DCB testing. Three sensors at tensile testing and one sensor at Mode-I DCB testing gather AE data. The results of clustered burst signals show a good accordance between both testing procedures, with a similar weighted peak frequency (WPF) range in each classified cluster. In total, three different clusters are determined. An assignment of these three clusters to the three dominant damage mechanisms, visually observed by microscopy, is suggested.}, language = {en} } @inproceedings{BaumerKastenmeierEhrlich, author = {Baumer, A. and Kastenmeier, Andreas and Ehrlich, Ingo}, title = {Investigation of Bolted Composite Joints with Different Reinforcement Elements at the Bolt Hole}, series = {4th Applied Research Conference, 5th July 2014, Ingolstadt}, booktitle = {4th Applied Research Conference, 5th July 2014, Ingolstadt}, editor = {Ziemann, Olaf and Mottok, J{\"u}rgen and Pforr, Johannes}, publisher = {Shaker}, pages = {255 -- 258}, language = {en} } @inproceedings{NonnKalwa, author = {Nonn, Aida and Kalwa, Christoph}, title = {The effect of microstructure, strain hardening and strain rate on the fracture behavior of high strength pipeline steels}, series = {2nd International Conference on Material Modelling (ICMM2), 31th August - 2nd September, 2011 at Mines Paris Tech, France}, booktitle = {2nd International Conference on Material Modelling (ICMM2), 31th August - 2nd September, 2011 at Mines Paris Tech, France}, language = {en} } @inproceedings{NonnVoelling, author = {Nonn, Aida and V{\"o}lling, Alexander}, title = {Lokale Spannungsanalyse bei Rissinitiierung}, series = {4. Workshop Kompetenzverbund Kerntechnik "Komponentensicherheit und Werkstoffverhalten", MPA Stuttgart, Germany}, booktitle = {4. Workshop Kompetenzverbund Kerntechnik "Komponentensicherheit und Werkstoffverhalten", MPA Stuttgart, Germany}, subject = {Rissverhalten}, language = {en} } @inproceedings{NonnKalwa, author = {Nonn, Aida and Kalwa, Christoph}, title = {Modeling of damage behavior of high strength pipeline steel}, series = {18th European Conference on Fractur: Fracture of Materials and Structures from Micro to Macro Scale, August 30 - September 03, 2010, Dresden, Germany}, booktitle = {18th European Conference on Fractur: Fracture of Materials and Structures from Micro to Macro Scale, August 30 - September 03, 2010, Dresden, Germany}, language = {en} } @inproceedings{NonnErdelenPepplerWesseletal., author = {Nonn, Aida and Erdelen-Peppler, Marion and Wessel, Waldemar and Mahn, Denise}, title = {How reliable are the current testing procedures for the safety assurance against crack propagation in seamless gas pipelines}, series = {Proceedings of the ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering (OMAE2014), Volume 4A: Structures, Safety and Reliability, June 8-13, 2014, San Francisco, USA}, booktitle = {Proceedings of the ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering (OMAE2014), Volume 4A: Structures, Safety and Reliability, June 8-13, 2014, San Francisco, USA}, doi = {10.13140/2.1.3190.6567}, abstract = {The worldwide growing energy demand with the exploration of new gas fields has promoted the development of high toughness seamless pipeline steels which should sustain the increasing demands resulting from the complex loading situations. One of the most important prerequisites for safe installation and operation of long distance gas transmission pipelines is the detailed knowledge and characterization of their fracture performance for specific applications. However, recent industry experience has revealed concerns related to the limitations and reliability of current test methods for brittle-to-ductile transition evaluation. Regarding the transition temperature evaluation, the critical issues involve Drop-Weight Tear Testing (DWTT) and full-scale West-Jefferson (WJ) test applied to the smaller pipes with diameter less than 500mm. The DWTT leads frequently to invalid results in terms of abnormal fracture appearance and inverse fracture occurrence. It is still not clear if this behavior is only owed to a testing effect, which material characteristics cause it and how far it reflects the full-scale behavior. Similar observations were made for the West-Jefferson tests, which could not be assessed in the standard manner either. Again, the question was towards testing effects and the behavior of the pipeline transporting gaseous media remains unanswered. Therefore, this paper aims at identifying open questions on basis of a literature study and own experimental results and showing possible ways forward in demonstrating safety in design against propagating fracture.}, language = {en} } @inproceedings{NonnErdelenPepplerWesseletal., author = {Nonn, Aida and Erdelen-Peppler, Marion and Wessel, Waldemar and Harksen, Silke and Mahn, Denise}, title = {How to assure fracture-propagation control for seamless gas pipelines?}, series = {Proceedings of the 2014 10th International Pipeline Conference (IPC2014), Volume 3: Operations, Monitoring, and Maintenance, Materials and Joining, September 29-October 3, 2014, Calgary, Canada}, booktitle = {Proceedings of the 2014 10th International Pipeline Conference (IPC2014), Volume 3: Operations, Monitoring, and Maintenance, Materials and Joining, September 29-October 3, 2014, Calgary, Canada}, doi = {10.1115/IPC2014-33169}, abstract = {Fracture propagation control in gas transmission gas pipelines belongs to the major design requirements for safe operation at high internal pressures. However, the current tests such as Drop-Weight-Tear Test (DWTT) and full-scale West-Jefferson (WJ) test reach the limits of their applicability with respect to transition temperature evaluation for seamless quenched and tempered small diameter pipes reflecting nowadays alloying concepts related to mechanical properties. Hereby, different geometry and material effects are evident which might lead to misinterpretation and unreliability of testing results. This paper aims to discuss open issues addressed in the literature and in own experimental findings with respect to reliability and transferability of testing methods, fracture parameters and their representativeness of seamless quenched and tempered pipeline behavior. By applying damage mechanics approach, it is possible to quantify the prevailing stress state and thus to understand the mechanisms controlling specific fracture appearance (ductile or brittle). Furthermore, studies were performed with objective to quantify the effect of different parameters (geometry, material and loading) on the fracture performance of the pipeline. The results from these investigations will serve as a basis for a safe pipeline design against propagating fracture.}, language = {en} } @inproceedings{NonnParedesNordhagenetal., author = {Nonn, Aida and Paredes, Marcelo and Nordhagen, H. O. and Munkejord, S. T. and Wierzbicki, Tomasz}, title = {Challenges in fluid-structure modeling of crack propagation and arrest in modern steel pipelines}, series = {14th International Congress on Fracture (ICF14), 18-23 June 2017, Rhodes, Greece}, booktitle = {14th International Congress on Fracture (ICF14), 18-23 June 2017, Rhodes, Greece}, pages = {1351 -- 1352}, language = {en} } @inproceedings{NonnParedesKeimetal., author = {Nonn, Aida and Paredes, Marcelo and Keim, Vincent and Wierzbicki, Tomasz}, title = {Comparison of Fracture Models to Quantify the Effects of Material Plasticity on the Ductile Fracture Propagation in Pipelines}, series = {Proceedings of the 2018 12th International Pipeline Conference, Volume 3: Operations, Monitoring, and Maintenance, Materials and Joining, September 24-28, 2018, Calgary, Alberta, Canada}, booktitle = {Proceedings of the 2018 12th International Pipeline Conference, Volume 3: Operations, Monitoring, and Maintenance, Materials and Joining, September 24-28, 2018, Calgary, Alberta, Canada}, doi = {10.1115/IPC2018-78366}, abstract = {Various numerical approaches have been developed in the last years aimed to simulate the ductile fracture propagation in pipelines transporting CO2 or natural gas. However, a reliable quantification of the influence of material plasticity on the fracture resistance is still missing. Therefore, more accurate description of the material plasticity on the ductile fracture propagation is required based on a suitable numerical methodology. In this study, different plasticity and fracture models are compared regarding the ductile fracture propagation in X100 pipeline steel with the objective to quantify the influence of plasticity parameters on the fracture resistance. The plastic behavior of the investigated material is considered by the quadratic yield surface in conjunction with a non-associated quadratic plastic flow potential. The strain hardening can be appropriately described by the mixed Swift-Voce law. The simulations of ductile fracture are conducted by an uncoupled, modified Mohr-Coulomb (MMC) and the micromechanically based Gurson-Tvergaard-Needleman (GTN) models. In contract to the original GTN model, the MMC model is capable of describing ductile failure over wide range of stress states. Thus, ductile fracture resistance can be estimated for various load and fracture scenarios. Both models are used for the simulation of fracture propagation in DWTT and 3D pressurized pipe sections. The results from the present work can serve as a basis for establishing the correlation between plasticity parameters and ductile fracture propagation.}, language = {en} } @inproceedings{NonnDahlBleck, author = {Nonn, Aida and Dahl, Winfried and Bleck, Wolfgang Peter}, title = {Damage Modelling and Safety Assessment of the Hybrid Welded Structures}, series = {5th German-Japanese Seminar "Materials, Processes and Components", Fraunhofer Institute for Mechanics of Materials, Freiburg, Germany}, booktitle = {5th German-Japanese Seminar "Materials, Processes and Components", Fraunhofer Institute for Mechanics of Materials, Freiburg, Germany}, language = {en} } @article{BleckDahlNonnetal., author = {Bleck, Wolfgang Peter and Dahl, Winfried and Nonn, Aida and Amlung, Lars and Feldmann, Markus and Sch{\"a}fer, Dirk and Eichler, Bj{\"o}rn}, title = {Numerical and experimental analyses of damage behaviour of steel moment connection}, series = {Engineering Fracture Mechanics}, volume = {76}, journal = {Engineering Fracture Mechanics}, number = {10}, doi = {10.1016/j.engfracmech.2009.03.004}, pages = {1531 -- 1547}, abstract = {Plastic design allows the exploitation of the full resistance of steel structures by taking advantage of stress-redistributions due to plastic strains exceeding the yield strain. Especially in seismic design the utilization of material reserves and the formation of plastic hinges play an important role. In devastating earthquakes in Northridge (USA) and Kobe (Japan) brittle fracture of welded connections in steel moment frames occurred prior to formation of plastic hinges and utilization of plastic material reserves. The subsequent research works resulted in improved design rules and recommendations for these kinds of failure. But to guarantee sufficient ductile performance of these connections also in the upper shelf region, plastic and earthquake resistant design rules should take into account degradation of strain capacity and toughness properties due to quasi static and especially seismic loading. In the scope of the current European project "Plastotough", the main objective is to derive quantified toughness design rules in the upper shelf based on the strain requirements opposed to strain capacities. This paper gives an overview over the research work in performance and shows recent results from experimental and numerical analyses performed within this project for monotonic and cyclic loading.}, language = {en} } @inproceedings{NonnWesselSchmidt, author = {Nonn, Aida and Wessel, Waldemar and Schmidt, Tanja}, title = {Application of finite element analysis for assessment of fracture behavior of modern high toughness seamless pipeline steels}, series = {23rd International Society of Offshore and Polar Engineering 2013 (ISOPE 2013), Anchorage, USA}, booktitle = {23rd International Society of Offshore and Polar Engineering 2013 (ISOPE 2013), Anchorage, USA}, doi = {10.13140/2.1.4239.2322}, abstract = {Fracture behavior of seamless pipeline material X65Q acc. to API 5L has been studied both experimentally and numerically at different loading conditions (quasi-static vs. dynamic) and temperatures. The recent findings have shown difficulties in applying well established methods for determination of transition behavior or prediction of ductile crack arrest for the new generation of high-toughness steels. The irregular fracture performance (e.g. so-called "abnormal inverse fracture" appearance, significant scattering in ductile-to-brittle-transition-temperature region, etc.) suggests that the influence of pipe dimensions, loading parameters, crack initiation resistance as well as testing procedure on the fracture behavior has been neither understood nor properly described. This work aims to shed light on these questions regarding the applicability of conventional methods and to better illuminate most relevant parameters affecting fracture behavior of high toughness steels. To achieve this goal, experimental data basis for analysis of fracture behavior in transition and upper shelf regime has been established by conducting quasi-static fracture mechanics tests and dynamic tests on Battelle Drop Weight Tear (BDWT or DWT) specimens at different temperatures. The evaluation of obtained test results in upper shelf has been additionally complemented by numerical simulation of damage behavior. The results highlight the influence of stress conditions on fracture behavior with reference to pipe dimensions and loading conditions and, subsequently, may be used as a basis for revision of existing design methods.}, subject = {Rissfortschritt}, language = {en} } @inproceedings{VoellingNonnSchneider, author = {V{\"o}lling, Alexander and Nonn, Aida and Schneider, Ingo}, title = {Anwendung des Koh{\"a}sivzonenmodells zur Abbildung von duktilem dynamischen Rissfortschritt in Gasfernleitungen}, series = {45. Tagung des AK Bruch, Berlin, Germany}, booktitle = {45. Tagung des AK Bruch, Berlin, Germany}, pages = {253 -- 262}, subject = {Ferngasleitung}, language = {de} } @article{KeimParedesNonnetal., author = {Keim, Vincent and Paredes, Marcelo and Nonn, Aida and M{\"u}nstermann, Sebastian}, title = {FSI-simulation of ductile fracture propagation and arrest in pipelines}, series = {International Journal of Pressure Vessels and Piping}, volume = {182}, journal = {International Journal of Pressure Vessels and Piping}, number = {May}, publisher = {Elsevier}, doi = {10.1016/j.ijpvp.2020.104067}, abstract = {The fracture propagation and arrest control for pipelines transporting rich natural gases and high vapor pressure liquids is based on the Battelle Two-Curve Model (BTCM). Distinct limitations of this model were demonstrated for past and modern steels and gas mixtures. These can be related to the insufficient description of individual physical processes and interactions between the pipe material and transported mixture during the running ductile fracture. In the past, fluid-structure interaction (FSI) models enabled a more sophisticated, coupled analysis of the failure scenario. To quantify their capability of describing the multi-physical processes, the FSI models need to be verified by experimental data from full-scale burst tests (FSBT). Therefore, this paper deals with the simulation of five FSBTs from the literature on API grade X65 pipes with different pipe geometries, mixtures and initial conditions. The FSI is modeled by the coupled Euler-Lagrange (CEL) method. The modified Mohr-Coulomb (MMC) model is implemented in the CEL framework to describe the deformation and ductile fracture in the X65/L450 pipes. 3D Euler equations are used to calculate the mixture decompression with the GERG-2008 equation of state defining the volumetric behavior of a CO2-rich mixture, CH4 and H2. The extended model considers the effect of soil backfill on the pipe deformation and inertia. The numerical predictions agree well with the experimental findings in terms of the crack propagation speed and arrest length underlining the capability of the developed numerical tool.}, subject = {Bruchmechanik}, language = {en} } @article{KeimMarxNonnetal., author = {Keim, Vincent and Marx, P. and Nonn, Aida and M{\"u}nstermann, Sebastian}, title = {Fluid-structure-interaction modeling of dynamic fracture propagation in pipelines transporting natural gases and CO2-mixtures}, series = {International Journal of Pressure Vessels and Piping}, volume = {175}, journal = {International Journal of Pressure Vessels and Piping}, number = {August}, publisher = {Elsevier}, doi = {10.1016/j.ijpvp.2019.103934}, abstract = {As part of current design standards, the Battelle Two-Curve Model (BTCM) is still widely used to predict and secure ductile crack arrest in gas transmission pipelines. For modern linepipe steels and rich natural gases or CO2 mixtures, the BTCM might lead to incorrect predictions. On the one hand, it suffers from the insufficient description of the individual physical processes in the pipe material and fluid itself. Furthermore, the model does not account for fluid-structure-interaction (FSI) effects during simultaneous running-ductile fracture (RDF) and mixture decompression. Numerical FSI models allow for a more sophisticated, coupled analysis of the driving forces for the failure of pipelines. This paper deals with the development of an FSI model for the coupled prediction of 3D pressure profiles acting on the inner pipe wall during crack propagation. The coupled Euler-Lagrange (CEL) method is used to link the fluid and structure models. In a Lagrange formulation, the modified Bai-Wierzbicki (MBW) model describes the plastic deformation and ductile fracture as a function of the underlying stress/strain conditions. The fluid behavior is calculated in a 3D model space by Euler equations and the GERG-2008 reference equation of state (EOS). The coupled CEL model is used to predict the RDF in small-diameter pipe sections for different fluid mixtures. The calculated 3D pressure distributions ahead and behind the running crack tip (CT) significantly differ in axial and circumferential directions depending on the mixture composition. The predicted FSI between the pipe wall and fluid decompression in 3D CEL/FSI model provides reliable knowledge about the pressure loading of the pipeline during RDF.}, subject = {Fluid-Struktur-Wechselwirkung}, language = {en} } @article{KeimNonnMuenstermann, author = {Keim, Vincent and Nonn, Aida and M{\"u}nstermann, Sebastian}, title = {Application of the modified Bai-Wierzbicki model for the prediction of ductile fracture in pipelines}, series = {International Journal of Pressure Vessels and Piping}, volume = {171}, journal = {International Journal of Pressure Vessels and Piping}, number = {March}, publisher = {Elsevier}, doi = {10.1016/j.ijpvp.2019.02.010}, pages = {104 -- 116}, abstract = {The complex mechanical and corrosive loads of modern pipeline systems transporting oil, natural gas and CO2 impose steadily increasing requirements on material properties. The majority of current design standards still limit the application of modern high toughness linepipe steels due to the simple specification of material requirements in terms of energy levels from Charpy impact or Battelle Drop-Weight-Tear (BDWT) tests. In consequence, research activities have been conducted recently aiming at developing modified or novel experimental methods for the characterization of the ductile fracture behavior. To quantify the effects of various parameters on fracture behavior and derive suitable correlations, it is necessary to accompany these activities by numerical simulations with appropriate ductile damage models. In this paper, the MBW model is applied to study the structural behavior of pipelines in ductile fracture regime. Due to its precise incorporation of the underlying load conditions, the damage model is successfully used to simulate the slant fracture behavior in Battelle Drop weight tear test specimens and pipe sections. In comparison to ductile damage models applied in former studies, namely the Gurson-Tvergaard-Needleman and Cohesive Zone model, the presented numerical methodology allows for a more detailed investigation of loading, material and geometry effects on fracture and crack arrest behavior of pipelines.}, language = {en} } @article{KeimCerroneNonn, author = {Keim, Vincent and Cerrone, Albert R. and Nonn, Aida}, title = {Using local damage models to predict fracture in additively manufactured specimens}, series = {International Journal of Fracture}, volume = {218}, journal = {International Journal of Fracture}, number = {1}, publisher = {Springer Nature}, doi = {10.1007/s10704-019-00371-z}, pages = {135 -- 147}, abstract = {This paper explores the efficacy of employing local damage models, normally applied to ductile material systems manufactured by subtractive techniques, to additively manufactured laboratory specimens. While these specimens were ductile and metallic, their additive character (i.e. porosity and surface roughness) could have had potential to activate multiple life-limiting failure paths, thus obfuscating failure prediction. Herein, two damage models are considered and compared: the micromechanical Gurson-Tvergaard-Needleman model and a Crack Band model of the strain-based, phenomenological genre. Simulations used to calibrate elastic and plastic material properties and predict damage in a novel, non-standard specimen were quasi-static, explicit. Both damage models proved capable in resolving the experimentally-observed failure path and associated loading conditions. The analyses described herein were made as part of the Third Sandia Fracture Challenge.}, language = {en} } @article{SchimmerLadewigMotschetal., author = {Schimmer, Florian and Ladewig, Sven and Motsch, Nicole and Hausmann, Joachim M. and Ehrlich, Ingo}, title = {Comparison of Low-Velocity Impact Damage Behavior of Unidirectional Carbon Fiber-Reinforced Thermoset and Thermoplastic Composites}, series = {Key Engineering Materials}, volume = {809}, journal = {Key Engineering Materials}, publisher = {Trans Tech Publications}, issn = {1662-9795}, doi = {10.4028/www.scientific.net/KEM.809.9}, pages = {9 -- 14}, abstract = {This paper investigates the damage behavior of thermoset and thermoplastic fiber-reinforced composites. The specimens were subjected to low-velocity impacts (LVI) to produce barely visible impact damages (BVID). To compare the dependency of the matrix system and the laminate lay-up on the impact damage, four test series were set up. Therefore, laminates with an epoxy (EP) and a polyether ether ketone (PEEK) matrix in a quasi-isotropic (QI) [+45/0/-45/90]2s and an orthotropic (OT) fiber lay-up [0/90]4s were manufactured. To eliminate the influence of variant fiber systems, the thermoplastic tape and the thermoset prepreg contain similar carbon fibers (CF). After impact testing with three different impact energies, inner damages were investigated by using ultrasonic analyses. To get a deeper understanding of the interior damage mechanisms, cross sections of the damaged areas were examined via reflected light microscopy. By using these destructive and non-destructive test methods, significant differences in the damage behavior of composites with thermoplastic and thermoset matrix systems were identified for both laminate lay-ups.}, language = {en} } @article{WiesentSchultheissLullaetal., author = {Wiesent, Lisa and Schultheiß, Ulrich and Lulla, Philipp and Nonn, Aida and Noster, Ulf}, title = {Mechanical properties of small structures built by selective laser melting 316 L stainless steel - a phenomenological approach to improve component design}, series = {Materials Science \& Engineering Technology}, volume = {51}, journal = {Materials Science \& Engineering Technology}, number = {12}, publisher = {Wiley}, doi = {10.1002/mawe.202000038}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-14718}, pages = {1615 -- 1629}, abstract = {Experimental investigations are conducted to quantify the influence of specimen thickness and orientation on the mechanical properties of selective laser melted stainless steel 316 L. The results indicate that the mechanical strength and ductility increase with increasing specimen thickness until a saturation value is reached from a specimen thickness of about 2 mm. Specimen orientation dependency is pronounced for thin specimens (<1.5 mm), whereas only small deviations in strength are observed for thicker specimens with orientations of 30°, 45° and 90° to build direction. The mechanical properties of the specimen orientation of 0° to build direction shows great deviation to the other orientations and the smallest overall strength. A reliable design of selective laser melted components should account for specimen thickness and orientation, e. g. by a correction factor. Furthermore, it is recommended to avoid loads vertical (90°) and parallel (0°) to build direction to guarantee higher ductility and strength.}, language = {en} } @inproceedings{AltenbuchnerHaugWeber, author = {Altenbuchner, Amelie and Haug, Sonja and Weber, Karsten}, title = {Exploratory Analysis of Motion Tracking Data in the Rehabilitation Process of Geriatric Trauma Patients}, series = {Studies in Health Technology and Informatic. Volume 260: dHealth 2019 - From eHealth to dHealth}, booktitle = {Studies in Health Technology and Informatic. Volume 260: dHealth 2019 - From eHealth to dHealth}, editor = {Hayn, Dieter and Eggerth, A. and Schreier, G{\"u}nter}, publisher = {IOS Press}, doi = {10.3233/978-1-61499-971-3-138}, pages = {138 -- 145}, abstract = {Background: This article is based on an ongoing long-term study, in which customary motion trackers measure steps during rehabilitation of geriatric trauma patients (Med=86 years). Objectives: Exploring steps after 28 days of measurement. Finding similarities in the data by running cluster analysis and formulating linear regressions models to predict steps through time. Methods: Two types of motion trackers (FitBitAlta HR and Garmin v{\´i}vofit 3) have been used to measure patients' (N=24) steps after hip fracture in two study groups. Cluster analysis detected three clusters for progress in number of steps that were tested for group differences with ANOVA. Regression analysis tested models for individual patients. Results: Three-cluster solutions showed significant differences for the average amount of steps after 5, 14, 21 and 28 days. Regression models could predict 71 \% of the individual patients' progress in study group 2. Conclusion: The long-term study will provide more data in the future to examine the three-cluster solution and to find out in what stage of rehabilitation the measurement of the steps could be used to predict individual rehabilitation.}, language = {en} } @article{KofianiNonnWierzbicki, author = {Kofiani, Kirki and Nonn, Aida and Wierzbicki, Tomasz}, title = {New calibration method for high and low triaxiality and validation on SENT specimens of API X70}, series = {International Journal of Pressure Vessels and Piping}, volume = {111-112}, journal = {International Journal of Pressure Vessels and Piping}, doi = {10.1016/j.ijpvp.2013.07.004}, pages = {187 -- 201}, abstract = {The determination of the exact mechanical properties of material is essential for an optimal and safe design of linepipes. It is especially important for the prevention of over-engineering and the reliable assessment of complex accidental loading, such as extreme bending due to loss of buoyancy of support, or abrupt ground movement. Currently, the focus of research in offshore deepwater installations and linepipes is towards pre-cracked structures with high triaxiality stress states and complex loading histories. At the same time, low triaxiality stress states must be correctly studied in order to represent shear dominated failure in pipes. A comprehensive experimental and numerical program was undertaken to determine the mechanical properties of the traditional API X70 grade of steel. The material was characterized for anisotropic plasticity, fracture initiation and uncracked ductility for various states of stress. The same material was also used for pre-cracked fracture toughness assessment. The experimental program included flat and round specimens. The first type of tests on flat butterfly-shaped, central hole, notched and circular disk specimens; were selected to address the low stress triaxiality range. Tests on round notched bar specimens and SENT fracture mechanics tests extended the characterization and verification process to higher stress triaxiality values. This program covered a wide range of stress conditions and demonstrated their effect on the material resistance to crack extension. Each test conducted was numerically simulated using solid finite element models, matching the exact geometric and loading history features. The numerical simulation provided information on the local stress and strain fields around the location of the potential or existing cracks. Based on the above hybrid experimental/numerical technique tailored for pipe applications, the MMC fracture model was calibrated. The model relates the material ductility not only to stress triaxiality but also to the Lode parameter. The predictive capabilities of the MMC were then evaluated in the case of SENT testing, used extensively in the pipeline industry. It was shown that the present fracture model calibration can describe fracture behavior of SENT experiments.}, language = {en} } @article{CerroneWawrzynekNonnetal., author = {Cerrone, Albert R. and Wawrzynek, Paul and Nonn, Aida and Paulino, Glaucio H. and Ingraffea, Anthony R.}, title = {Implementation and verification of the Park-Paulino-Roesler cohesive zone model in 3D}, series = {Engineering Fracture Mechanics}, volume = {120}, journal = {Engineering Fracture Mechanics}, doi = {10.1016/j.engfracmech.2014.03.010}, pages = {26 -- 42}, abstract = {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.}, language = {en} } @article{CerroneNonnHochhalteretal., author = {Cerrone, Albert R. and Nonn, Aida and Hochhalter, Jacob D. and Bomarito, Geoffrey F. and Warner, J. E. and Carter, Bruce J.}, title = {Predicting failure of the Second Sandia Fracture Challenge geometry with a real-world, time constrained, over-the-counter methodology}, series = {International Journal of Fracture}, volume = {198}, journal = {International Journal of Fracture}, number = {1-2}, doi = {10.1007/s10704-016-0086-x}, pages = {117 -- 126}, abstract = {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.}, language = {en} } @article{NonnDahlBleck, author = {Nonn, Aida and Dahl, Winfried and Bleck, Wolfgang Peter}, title = {Numerical modelling of damage behaviour of laser-hybrid welds}, series = {Engineering Fracture Mechanics}, volume = {75}, journal = {Engineering Fracture Mechanics}, doi = {10.1016/j.engfracmech.2007.10.015}, pages = {3251 -- 3263}, abstract = {The effect of laser-hybrid welds on deformation and failure behaviour of fracture mechanics specimens is investigated in order to provide quantitative prediction of damage tolerance and residual strength. The simulation of crack initiation and crack extension in hybrid welds is performed by applying GTN damage model. The identification of damage parameters requires combined numerical and experimental analyses. The tendency to crack path deviation during crack growth depends strongly on the constraint development at the interface between base and weld metal. In order to quantify the influence of local stress state on the crack path deviation, the initial crack location is varied. Finally, the results from fracture mechanics tests are compared to real component, beam-column-connection, with respect to fracture resistance.}, language = {en} } @article{RueckBierlMatysik, author = {R{\"u}ck, Thomas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Development and characterization of a laboratory setup for photoacoustic NO2 determination based on the excitation of electronic 2B2 and 2B1 states using a low-cost semiconductor laser}, series = {Sensors and Actuators A: Physical}, volume = {258}, journal = {Sensors and Actuators A: Physical}, publisher = {Elsevier}, address = {Amsterdam, Niederlande}, doi = {10.1016/j.sna.2017.03.024}, pages = {193 -- 200}, abstract = {This work gives a detailed characterization of a laboratory setup for photoacoustic NO2 trace gas detection at the ppb level. The signal generation is based on the excitation of electronic 2B2 and 2B1 states using a low-cost semiconductor laser emitting at 450 nm. An acoustic resonator was used for signal amplification and the modulation frequency of the laser was determined to 3395 Hz in order to gain maximum signal amplification. The quality of resonant amplification was determined to 7.9. The gas samples were NO2 calibration gases diluted with pure nitrogen. The signal-to-noise ratio (SNR) dependency on the flow rate Q and the lock-in time constant τLIA was investigated, respectively, and the optimum values were specified to Q = 500 mL/min and τLIA = 2 s. In case of ambient noise, increasing τLIA to 10 s was evaluated as sufficient for SNR preservation. The noise level was measured in the absence of NO2 and it was determined to be composed of 51\% electronic noise and 49\% gas flow noise. With the analyte concentration ranging from 300 ppbV to 100 ppmV, the linear dependency of the photoacoustic amplitude on the NO2 concentration was specified, the sensitivity was determined to 110 μV/ppmV and the maximum measurement error was calculated to ±0.8\%. The detection limit was determined to 2.0 ppbV. Furthermore, the stability of the signal was investigated and a maximum drift of ±1\% was observed within a measuring period of 30 min. The response time τ90 was specified to 58 s. All results considered, this photoacoustic measuring system, which is based on low-cost signal generation and detection units, provides an excellent basis in view of developing a portable device for photoacoustic trace gas detection.}, language = {en} } @inproceedings{HauslerRothAumeretal., author = {Hausler, Peter and Roth, Carina and Aumer, F. and Vitzthumecker, Thomas and Genslein, Christa and Hirsch, Thomas and Bierl, Rudolf}, title = {Miniaturisiertes Sensorsystem zur Oberfl{\"a}chenplasmonenresonanzspektroskopie}, series = {118. Jahrestagung der deutschen Gesellschaft f{\"u}r angewandte Optik (DGaO), 6.-10. Juni 2017, Dresden}, booktitle = {118. Jahrestagung der deutschen Gesellschaft f{\"u}r angewandte Optik (DGaO), 6.-10. Juni 2017, Dresden}, abstract = {Die Oberfl{\"a}chenplasmonenresonanzspektroskopie (SPR) wird aufgrund ihrer Vorz{\"u}ge der zerst{\"o}rungs- und markierungsfreien Messung, sowie der hohen Sensitivit{\"a}t sehr erfolgreich im Labormaßstab eingesetzt. Aufgrund der hohen Kosten geschieht dies bislang haupts{\"a}chlich in der Bioanalytik und dem Wirkstoffscreening. Gezeigt wird ein Ansatz, mit dem diese Technologie auf ein ultrakompaktes, kosteng{\"u}nstiges Sensorsystem {\"u}bertragen wird, welches in der Lage ist, hoch-sensitiv {\"A}nderungen im Brechungsindex von 10-6 Einheiten (RIU) zu detektieren. F{\"u}r Wasser bewirkt eine Temperaturschwankung von 1 K bereits eine {\"A}nderung von 1 mRIU. Daher wird durch ein integriertes Referenzsystem, sowie die Miniaturisierung erreicht, dass das System gegen{\"u}ber Temperaturschwankungen, weitestgehend stabil ist. In dem MOEMS wird anstatt der konventionellen 1-Punkt bzw. 2-Punkt Messung ein bildgebendes Verfahren angewendet. Die Sensorfl{\"a}che von 15 x 15 mm wird dabei mit einem handels{\"u}blichen 4 Mio. Pixel CMOS Sensor ausgewertet. Um verl{\"a}ssliche Datenpunkte zu erhalten ben{\"o}tigt man eine Fl{\"a}che von 10 x 10 Pixel. Demzufolge k{\"o}nnen auf dem Sensor theoretisch bis zu 40.000 Sensorspots parallel ausgewertet werden.}, language = {de} } @inproceedings{RothHauslerBierl, author = {Roth, Carina and Hausler, Peter and Bierl, Rudolf}, title = {Einbindung eines 2D-Photodetektors in einen hochintegrierten SPR-Imaging-Sensor}, series = {118. Jahrestagung der deutschen Gesellschaft f{\"u}r angewandte Optik (DGaO), 6.-10. Juni 2017, Dresden}, booktitle = {118. Jahrestagung der deutschen Gesellschaft f{\"u}r angewandte Optik (DGaO), 6.-10. Juni 2017, Dresden}, abstract = {Mit der Oberfl{\"a}chenplasmonenresonanzspektroskopie (SPR) k{\"o}nnen Brechungsindex{\"a}nderungen eines Analyten von bis zu 10-6 RIU detektiert werden. Das SPR-Imaging bietet heute gegen{\"u}ber der konventionellen SPR-Analyse die M{\"o}glichkeit, mehrere einzelne Messungen parallel durchf{\"u}hren zu k{\"o}nnen. Mit Hilfe eines zweidimensionalen Sensorchips und einer leistungsf{\"a}higen Boardlevelkamera k{\"o}nnen die Abbildungen des Chips direkt an einen Rechner {\"u}bertragen und dort verarbeitet werden. Aufgrund unterschiedlicher Winkelstellungen und der Geometrie des Aufbaus entstehen Stauchungen und Streckungen des abgebildeten Sensorchips, die mit verschiedenen Ans{\"a}tzen aus der Bildverarbeitung ausgeglichen werden, um die Bilder miteinander vergleichen zu k{\"o}nnen. Zudem wird die G{\"u}te der Referenz- und Messbereiche des Chips bestimmt. Diese Algorithmen sind nur m{\"o}glich aufgrund der heutigen, leistungsf{\"a}higen Rechner und der immer gr{\"o}ßer werdenden Durchsatzraten der Kameras. Dabei kommt in dieser Anwendung der relativ neue Kamerastandard USB3 Vision zum Einsatz. Dieser zeichnet sich zus{\"a}tzlich durch das Plug and Play und seinen Standardstecker, der an (fast) jedem Rechner vorhanden ist, aus.}, language = {de} } @inproceedings{GensleinHauserKirchneretal., author = {Genslein, Christa and Hauser, Peter and Kirchner, Eva-Maria and Bierl, Rudolf and Baeumner, Antje J. and Hirsch, Thomas}, title = {Detection of small molecules with surface plasmon resonance by synergistic plasmonic effects of nanostructured surfaces and graphene}, series = {SPIE Proceedings, Plasmonics in Biology and Medicine XIV, 2017, San Francisco, California}, volume = {10080}, booktitle = {SPIE Proceedings, Plasmonics in Biology and Medicine XIV, 2017, San Francisco, California}, number = {1008001F}, doi = {10.1117/12.2252256}, abstract = {Surface plasmon resonance depends on the dielectric medium at the vicinity and makes it a quasi-universal detector. Therefore, and due to the label-free nature, SPR is a widely used sensing tool for real-time monitoring molecular interactions of various analytes. However, detection of highly diluted analytes and small molecules (< 400 Da) is still challenging. Gold nanohole arrays provide plasmonic hotspots with improved surface sensitivity and 2D carbon nanomaterials enable binding near the surface. Both effects together are promising in the development of SPR sensors for the efficient determination of small molecules. Graphene is known for efficient binding of molecules with delocalized aromatic π-systems. Additionally, the electromagnetic field is locally enhanced and modulated by the interaction of graphene photonics with the plasmonics of metal nanostructures. The advantages of chemical vapor deposition (CVD) graphene over reduced graphene oxide (rGO) is illustrated by a proof of concept study. In comparison to substrates consisting of a continuous film the surface sensitivity is enhanced for a nanohole arrays and further improved for CVD graphene functionalization in contrast to rGO. The feasibility of the sensor was demonstrated for the detection of adenine down to a concentration of 0.9 μM.}, language = {en} } @article{ZaglerLandgrafRuecketal., author = {Zagler, Andreas and Landgraf, Ferdinand and R{\"u}ck, Thomas and Bierl, Rudolf}, title = {Entwicklung eines mikromechanischen kapazitiven Schalldetektors im resonanten Betrieb f{\"u}r die photoakustische Spurengasanalyse}, series = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, journal = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, publisher = {VDE-Verlag}, address = {Berlin}, language = {de} } @inproceedings{WeiglGaidaRuecketal., author = {Weigl, Stefan and Gaida, Peter and R{\"u}ck, Thomas and Bierl, Rudolf}, title = {Portable Measurement Unit for NO2 Trace Gas Detection}, series = {PHOTOPTICS 2018, 6th International Conference on Photonics, Optics and Laser Technology, 25 - 27 January 2018, Funchal Madeira}, booktitle = {PHOTOPTICS 2018, 6th International Conference on Photonics, Optics and Laser Technology, 25 - 27 January 2018, Funchal Madeira}, language = {en} } @misc{HauslerRothVitzthumeckeretal., author = {Hausler, Peter and Roth, Carina and Vitzthumecker, Thomas and Fischer, Johannes and Bierl, Rudolf}, title = {Motionless SPR-angle scan with a miniaturized device}, series = {Europtrode XIV, Naples, 25-28 March 2018}, journal = {Europtrode XIV, Naples, 25-28 March 2018}, language = {en} } @inproceedings{RueckLaeppleBierl, author = {R{\"u}ck, Thomas and L{\"a}pple, I. and Bierl, Rudolf}, title = {Photoakustische Spurengasanalytik von NO2 im ppt-Bereich (10^-12) bei Verwendung kosteng{\"u}nstiger Einzelkomponenten}, series = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, booktitle = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, publisher = {VDE-Verlag}, address = {Berlin}, isbn = {978-3-8007-4491-6}, language = {de} } @inproceedings{ZhouLandgrafRuecketal., author = {Zhou, Qi and Landgraf, Ferdinand and R{\"u}ck, Thomas and Bierl, Rudolf}, title = {Resonance frequency tuning and process design of a micromechanical capacitive cantilever in a photoacoustic trace-gas sensing device}, series = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, booktitle = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, publisher = {VDE-Verlag}, address = {Berlin}, isbn = {978-3-8007-4491-6}, abstract = {Photoacoustic spectroscopy is an efficient method to detect the concentration of trace gases with following advantages: short response time, high sensitivity, continuous and real-time monitoring and the option of miniaturization without the need of complex mirror-based multi-pass cell designs. A micromechanical cantilever is used as a key component in a two-part "Cantilever-Resonator" system that detects the weak photoacoustic signal. The resonance frequency of cantilever needs to be tuned to match the resonance frequency of resonator in order to achieve the maximum vibration amplitude of the "Cantilever-Resonator" system. This paper reports a post-fabrication method to tune the resonance frequency of cantilevers via focused ion beam (FIB) and a capacitive solution for the cantilever to transform the acoustic signal to electrical signal.}, language = {en} } @inproceedings{Fischer, author = {Fischer, Johannes}, title = {Miniaturisierter plasmonischer Sensor f{\"u}r das Monitoring von Weichmachern in Gew{\"a}sserproben}, series = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, booktitle = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, publisher = {VDE-Verlag}, address = {Berlin}, isbn = {978-3-8007-4491-6}, language = {de} } @inproceedings{HauslerGensleinRothetal., author = {Hausler, Peter and Genslein, Christa and Roth, Carina and Hirsch, Thomas and Bierl, Rudolf}, title = {Mikro-Opto-Elektro-Mechanisches Sensorsystem zur Oberfl{\"a}chenplasmonenresonanzspektroskopie}, series = {MikroSystemTechnik Kongress 2017 : MEMS, Mikroelektronik, Systeme 23.-25. Oktober 2017 in M{\"u}nchen}, booktitle = {MikroSystemTechnik Kongress 2017 : MEMS, Mikroelektronik, Systeme 23.-25. Oktober 2017 in M{\"u}nchen}, number = {CD-ROM}, publisher = {VDE-Verlag}, address = {Berlin}, isbn = {978-3-8007-4491-6}, pages = {645 -- 647}, abstract = {Gezeigt wird die Miniaturisierung eines Messsystems f{\"u}r Oberfl{\"a}chenplasmonenresonanzspektroskopie (SPR), einer markierungs-, sowie zerst{\"o}rungsfreien als auch hoch sensitiven Technologie. Aufgrund der hohen Kosten klassischer SPR-Ger{\"a}te wird sie bisher jedoch vornehmlich in der Bio- und Medizintechnik eingesetzt. Das Messprinzip erm{\"o}glicht die Erfassung von Brechungsindex{\"a}nderungen nahe einer Oberfl{\"a}che. Der Transfer dieser Technologie von Laborger{\"a}ten hin zu einem miniaturisierten Sensorsystem senkt die Kosten, macht das System robuster und erm{\"o}glicht so ein wesentlich breiteres Anwendungsspektrum. Ein sehr vielversprechendes Merkmal des hier vorgestellten Systems ist die M{\"o}glichkeit den SPR-Effekt winkelabh{\"a}ngig zur Lichtquelle ohne bewegliche Bauteile zu verfolgen. The miniaturization of Surface Plasmon Resonance (SPR) technology, which mainly finds its applications in pharmaceutical screening and biotechnology so far, is described. SPR spectroscopy is a label-free, non destructive and highly sensitive measurement principle which is capable of detecting changes in the refractive index in striking distance to a gold surface. A transfer of this technology to a miniaturized sensor will broaden the range of possible applications. A promising feature which is included in the miniaturized system is the angle-dependent recording of the SPR signals without moving parts.}, language = {de} } @inproceedings{GaidaWeiglRuecketal., author = {Gaida, Peter and Weigl, Stefan and R{\"u}ck, Thomas and Bierl, Rudolf}, title = {Portable photoakustische Messeinheit zur NO2 Detektion im Spurenbereich}, series = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, booktitle = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, publisher = {VDE-Verlag}, address = {Berlin}, isbn = {978-3-8007-4491-6}, language = {de} } @article{GensleinHauslerKirchneretal., author = {Genslein, Christa and Hausler, Peter and Kirchner, Eva-Maria and Bierl, Rudolf and Baeumner, Antje J. and Hirsch, Thomas}, title = {Graphene-enhanced plasmonic nanohole arrays for environmental sensing in aqueous samples}, series = {Beilstein Journal of Nanotechnology}, journal = {Beilstein Journal of Nanotechnology}, number = {7}, doi = {10.3762/bjnano.7.150}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:355-epub-398623}, pages = {1564 -- 1573}, abstract = {The label-free nature of surface plasmon resonance techniques (SPR) enables a fast, specific, and sensitive analysis of molecular interactions. However, detection of highly diluted concentrations and small molecules is still challenging. It is shown here that in contrast to continuous gold films, gold nanohole arrays can significantly improve the performance of SPR devices in angle-dependent measurement mode, as a signal amplification arises from localized surface plasmons at the nanostructures. This leads consequently to an increased sensing capability of molecules bound to the nanohole array surface. Furthermore, a reduced graphene oxide (rGO) sensor surface was layered over the nanohole array. Reduced graphene oxide is a 2D nanomaterial consisting of sp2-hybridized carbon atoms and is an attractive receptor surface for SPR as it omits any bulk phase and therefore allows fast response times. In fact, it was found that nanohole arrays demonstrated a higher shift in the resonance angle of 250-380\% compared to a continuous gold film. At the same time the nanohole array structure as characterized by its diameter-to-periodicity ratio had minimal influence on the binding capacity of the sensor surface. As a simple and environmentally highly relevant model, binding of the plasticizer diethyl phthalate (DEP) via π-stacking was monitored on the rGO gold nanohole array realizing a limit of detection of as low as 20 nM. The concentration-dependent signal change was studied with the best performing rGO-modified nanohole arrays. Compared to continuous gold films a diameter-to-periodicity ratio (D/P) of 0.43 lead to a 12-fold signal enhancement. Finally, the effect of environmental waters on the sensor was evaluated using samples from sea, lake and river waters spiked with analytically relevant amounts of DEP during which significant changes in the SPR signal are observed. It is expected that this concept can be successfully transferred to enhance the sensitivity in SPR sensors.}, language = {en} } @inproceedings{HollerHauslerRothetal., author = {Holler, Sven and Hausler, Peter and Roth, Carina and Bierl, Rudolf}, title = {Gestapelte Au-Al-Au und Au-Ag-Au Schichten als aktive Schichten f{\"u}r die Oberfl{\"a}chenplasmonenresonanzspektroskopie}, series = {5. Landshuter Symposium Mikrosystemtechnik, M{\"a}rz 2016}, booktitle = {5. Landshuter Symposium Mikrosystemtechnik, M{\"a}rz 2016}, publisher = {Fachhochschule Landshut}, address = {Landshut}, isbn = {978-3-9812696-9-7}, pages = {192 -- 198}, language = {de} } @inproceedings{RothHauslerBierl, author = {Roth, Carina and Hausler, Peter and Bierl, Rudolf}, title = {Einbindung eines CMOS-Detektors in einen hochintegrierten SPR-Sensor}, series = {5. Landshuter Symposium Mikrosystemtechnik, M{\"a}rz 2016}, booktitle = {5. Landshuter Symposium Mikrosystemtechnik, M{\"a}rz 2016}, publisher = {Fachhochschule Landshut}, address = {Landshut}, isbn = {78-3-9812696-9-7}, pages = {200 -- 205}, language = {de} }