TY - CHAP A1 - Mlikota, Marjo A1 - Schmauder, Siegfried A1 - Mitevski, Bojan A1 - Weiß, Sabine ED - Deng, Jiamei ED - Liu, Quingjun T1 - Scientific Multiscale and Multidisciplinary Analysis of Deformation and Damage in the Case of Oligocrystalline Structures T2 - Computer Science and Engineering Technology N2 - This paper serves as an overview of the ongoing research in the field of multiscale and multidisciplinary analysis of deformation and damage in the case of oligocrystalline structures. The research focuses on experimental measurement and numerical calculation of ductile failure in the X2CrNiMo18-15-3 (AISI 316L) stainless steel. An embedding numerical technique is employed where crystal plasticity theory is used to represent plastic deformation in the material and element removal technique based on Rice&Tracey damage model for ductile void growth to simulate damage initiation inside the material, which is observed in the experiments. Additionally, the crystal plasticity model is supported by a hierarchical multiscale approach connecting nano-, micro- and meso-scales. Y1 - 2016 SN - 978-981-4651-00-4 SP - 113 EP - 118 PB - World Scientific Publishing CY - Singapore ER - TY - GEN A1 - Lasko, Galina A1 - Yang, Yitong A1 - Weiss, Sabine A1 - Schmauder, Siegfried A1 - Dogahe, Kiarash T1 - FEM Simulations of Fatigue Crack Initiation in the Oligocrystalline Microstructure of Stents T2 - Materials N2 - For over two decades, vascular stents have been widely used to treat clogged vessels,serving as a scaffold to enlarge the narrowed lumen and recover the arterial flow area. High-purityoligocrystalline austenitic steel is usually applied for the production of stents. Despite the popularityand benefit of stenting, it still may cause serious clinical adverse issues, such as in-stent restenosisand stent fracture. Therefore, the study of the mechanical properties of stents and in particularthe prediction of their life cycles are in the focus of materials research. In our contribution, withinthe finite element method, a two-scale model of crack initiation in the microstructure of stents iselaborated. The approach is developed on the basis of the physically based Tanaka–Mura model(TMM), considering the evolution of shear bands during the crack initiation phase. The model allowsfor the analysis of the microstructure with respect to the life cycles of real materials. The effects ofdifferent loading conditions, grain orientation, and thickness of the specimen on Wöhler curves wereanalysed. It was found that the microstructural features of oligocrystals are very sensitive to differentloading conditions with respect to their fatigue behaviour and play a major role in fatigue crackinitiation. Different grain-orientation distributions result in qualitative and quantitative differencesin stress distribution and in the number of cycles for crack initiation. It was found that presence ofa neutral zone in the cut-out of the microstructure under three-point-bending loading conditionschanges the qualitative and quantitative patterns of stress distribution and affects the number ofcycles for crack initiation. It was found that under both tensile and bending loading conditions,thicker specimens require more cycles for crack initiation. The Wöhler curves for crack initiation inoligocrystalline microstructures of stents could be compared with the ones in the experiment, takinginto account that for high cyclic fatigue (HCF), typically, more than 70% of the cycles refer to crackinitiation. The developed numerical tools could be used for the material design of stents KW - SCHM 746/222-1 KW - WE 2671/11-1 Y1 - 2023 UR - https://www.mdpi.com/1996-1944/16/17/6003 U6 - https://doi.org/10.3390/ma16176003 VL - 16 IS - 17 ER -