Simulation-Free Identification of the Reduced Hosford-Coulomb Ductile Fracture Criterion for Nimonic Sheets Assisted by the Virtual Fields Method

Abstract

An inverse method assisted by the finite element-based virtual fields (FE-VFM) is proposed to identify the ductile fracture criteria without finite element analyses. The proposed method was applied to obtain the reduced Hosford–Coulomb (HC) fracture criterion of Nimonic thin sheets. In the proposed method, the strain hardening of the Nimonic sheets was inversely measured by the FE-VFM using digital image correlation measurements in notched tensile tests. Then, damage fields were optimized to identify the material parameters of the HC model with the stress and strain fields calculated by the FE-VFM. Finally, the measured fracture criterion was converted into a fracture-forming limit diagram (FFLD) for validation. The predicted FFLD showed good agreement with the experimental results.