Title:

Predicting fracture toughness with microstructure sensitivity using an elasto-viscoplastic fast Fourier transform model

This research presents a formulation of an elasto-viscoplastic fast Fourier transform (EVPFFT) model that can handle nonperiodic boundary conditions and local displacement boundary conditions imposed over a microstructural cell. The formulation is applied to simulate fracture toughness of stainless steel 304, and the method is verified using a crystal plasticity finite element model. The process of preparing mesh of notched specimens is described, which involved creating Phyton scripts for cutting in Abaqus and Sculpt scripts for meshing in Cubit of complex microstructural cells of measured data processed in Dream3D. In contrast, the EVPFFT model circumvents mesh generation of notched specimens. Given that and the efficiency of the EVPFFT model, a statistical distribution of fracture toughness is obtained using EVPFFT in function of local microstructures surrounding notches. Such distribution is then used to reduce uncertainty in macroscopic, empirical models of material performance under service conditions. The efficiency of the fast Fourier transform algorithm is demonstrated, making it suitable for running on high-performance computer platforms. The methodology developed in this research provides a practical simulation tool for predicting fracture toughness of explicit microstructures, and the distribution of fracture toughness is obtained in function of cracks embedded in these structures.

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