Strain-rate and stress-state dependent ductile fracture model of S690 high-strength steel

Abstract

The stress-state and strain-rate dependent ductile fracture initiation property of S690 high-strength steel is investigated in this study through experiments and simulations. A total of 14 specimens, including uniaxial tension, notched tension, central hole, plane strain, and in-plane pure shear specimens, are tested in the experimental programme. The Cowper–Symonds-type rate correction term is considered in the yield function and the three-dimensional ductile fracture initiation locus. Linear and non-linear damage accumulation evolution laws are discussed for specimens under various degrees of non-proportional loading. The extended model with the damage evolution is implemented in a user-defined material subroutine, VUMAT, and applied to the numerical simulations. A hybrid experimental and numerical approach is adopted to calibrate the key parameters. Then, a stress-state and strain-rate dependent ductile fracture model of S690 high-strength steel is proposed and validated in this study.