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Article Citation - WoS: 12Skeletonization-based beam finite element models for stochastic bicontinuous materials: Application to simulations of nanoporous gold(Cambridge Univ Press, 2018) Soyarslan, Celal; Argeso, Hakan; Borgmann, SwantjeAn efficient representative volume element generation strategy is developed in modeling nanoporous materials. It uses periodic 3D beam finite element (FE) models derived from skeletonization of spinodal-like stochastic microstructures produced by a leveled random field. To mimic stiffening with agglomeration of the mass at junctions, an increased Young's modulus is assigned to the elements within the junction zone. The effective Young's modulus, Poisson's ratio, and universal anisotropy index are computed. A good agreement of the Young's modulus predictions with those obtained from experimental results for phase volume fractions 0.20 < phi(B) < 0.50 is observed. Moreover, the elastic anisotropy index of the generated beam networks shows sufficient proximity to isotropy. Finally, it is demonstrated that, as compared to the simulation statistics of voxel-FE models, for the beam-FE models over 500-fold computational acceleration with 250-fold less memory requirement is provided.Article Citation - WoS: 39Citation - Scopus: 44Application of Continuum Damage Mechanics in Discontinuous Crack Formation: Forward Extrusion Chevron(Wiley-v C H verlag Gmbh, 2008) Soyarslan, Celal; Tekkaya, A. Erman; Akyuz, UgurhanMaterializing Continuum Damage Mechanics (CDM), numerical modeling of discrete internal cracks, namely central bursts, in direct forward extrusion process is presented. Accordingly, in a thermodynamically consistent setting, a local Lemaitre variant damage model with quasi-unilateral evolution is coupled with hyperelastic-plasticity. The formulations are constructed in the principal axes where simultaneous local integration schemes are efficiently developed. To this end, the framework is implemented as ABAQUS/VUMAT subroutine to be used in an explicit FE solution scheme, and utilized in direct forward extrusion simulations for bearing steel, 100Cr6. Discontinuous cracks are obtained with the element deletion procedure, where the elements reaching the critical damage value are removed from the mesh. The periodicity of the cracks shows well accordance with the experimental facts. The investigations reveal that, application of the quasi-unilateral conditions together with the crack closure parameter has an indispensable effect on the damage accumulation zones by determining their internal or superficial character. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
