TY - JOUR A1 - Romano, Marco A1 - Ehrlich, Ingo A1 - Gebbeken, Norbert T1 - Structural mechanic material damping in fabric reinforced composites BT - a review JF - Archives of Materials Science and Engineering (ArchivesMSE) N2 - 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. Y1 - 2017 U6 - https://doi.org/10.5604/01.3001.0010.7747 VL - 88 IS - 1 SP - 12 EP - 41 ER - TY - JOUR A1 - Valentino, Piergiorgio A1 - Sgambitterra, Emanuele A1 - Furgiuele, Franco A1 - Romano, Marco A1 - Ehrlich, Ingo A1 - Gebbeken, Norbert T1 - Mechanical characterization of basalt woven fabric composites BT - numerical and experimental investigation JF - Frattura ed Integrità Strutturale (Fracture and Structural Integrity) N2 - Basalt fabric composite, with different twill wave reinforcements, i.e. twill 2/2 and twill 1/3, have been studied in this work by means of experimental tests and numerical finite element (FE) simulations. As fabric reinforcements show repeating undulations of warp and fill yarn, simple mixtures law cannot be applied. As a consequence, the mesoscopic scale, lying between the microscopic and the macroscopic one, has to be taken into account to mechanically characterize a fabric reinforced composite. The aim of this work is to evaluate the stiffness of a fabric reinforced composite in warp and fill direction. In particular a numerical FE model, assuming elliptical sections and sinusoidal shape of the yarns, has been implemented and experimental tests have been carried out in order to validate the proposed model. Finally, the strength and the failure modes le orientation, have been experimentally investigated. Y1 - 2014 U6 - https://doi.org/10.3221/IGF-ESIS.28.01 VL - 8 IS - 28 SP - 1 EP - 11 ER - TY - JOUR A1 - Romano, Marco A1 - Hoinkes, Carl J. J. A1 - Ehrlich, Ingo A1 - Höcherl, Johannes A1 - Gebbeken, Norbert T1 - Experimental investigation of fibre reinforced plastics with hybrid layups under high-velocity impact loads JF - Frattura ed Integrità Strutturale (Fracture and Structural Integrity) N2 - 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. Y1 - 2014 U6 - https://doi.org/10.3221/IGF-ESIS.29.34 VL - 8 IS - 29 SP - 384 EP - 398 ER - TY - RPRT A1 - Putzer, Michael A1 - Rasmussen, John A1 - Ehrlich, Ingo A1 - Gebbeken, Norbert A1 - Dendorfer, Sebastian ED - Baier, Wolfgang T1 - Muskuloskelettale Simulation zur Untersuchung des Einflusses geometrischer Parameter der Wirbelkörper auf die Belastung der Lendenwirbelsäule T2 - Forschungsbericht 2013 / Ostbayerische Technische Hochschule Regensburg Y1 - 2013 UR - https://doi.org/10.35096/othr/pub-799 SP - 60 EP - 61 CY - Regensburg ER - TY - JOUR A1 - Wiesent, Lisa A1 - Spear, Ashley A1 - Nonn, Aida T1 - Computational analysis of the effects of geometric irregularities on the interaction of an additively manufactured 316L stainless steel stent and a coronary artery JF - Journal of the Mechanical Behavior of Biomedical Materials N2 - Customized additively manufactured (laser powder bed fused (L-PBF)) stents could improve the treatment of complex lesions by enhancing stent-artery conformity. However, geometric irregularities inherent for L-PBF stents are expected to influence not only their mechanical behavior but also their interaction with the artery. In this study, the influence of geometrical irregularities on stent-artery interaction is evaluated within a numerical framework. Thus, computed arterial stresses induced by a reconstructed L-PBF stent model are compared to those induced by the intended stent model (also representing a stent geometry obtained from conventional manufacturing processes) and a modified CAD stent model that accounts for the increased strut thickness inherent for L-PBF stents. It was found that, similar to conventionally manufactured stents, arterial stresses are initially related to the basic stent design/topology, with the highest stresses occurring at the indentations of the stent struts. Compared to the stent CAD model, the L-PBF stent induces distinctly higher and more maximum volume stresses within the plaque and the arterial wall. In return, the modified CAD model overestimates the arterial stresses induced by the L-PBF stent due to its homogeneously increased strut thickness and thus its homogeneously increased geometric stiffness compared with the L-PBF stent. Therefore, the L-PBF-induced geometric irregularities must be explicitly considered when evaluating the L-PBF stent-induced stresses because the intended stent CAD model underestimates the arterial stresses, whereas the modified CAD model overestimates them. The arterial stresses induced by the L-PBF stent were still within the range of values reported for conventional stents in literature, suggesting that the use of L-PBF stents is conceivable in principle. However, because geometric irregularities, such as protruding features from the stent surface, could potentially damage the artery or lead to premature stent failure, further improvement of L-PBF stents is essential. KW - Laser powder bed fusion (L-PBF) KW - Cardiovascular stents KW - Finite element analysis (FEA) KW - Geometrical imperfections KW - Stent-artery interaction Y1 - 2022 U6 - https://doi.org/10.1016/j.jmbbm.2021.104878 SN - 1751-6161 VL - 125 PB - Elsevier ER - 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 -