Experiments and numerical simulations with the H-specimen on damage and fracture of ductile metals under non-proportional loading paths

Abstract

The paper deals with a series of new experiments and corresponding numerical simulations to study the effect of non-proportional loading paths on damage and fracture behavior of ductile metals. In this context, a thermodynamically consistent anisotropic continuum damage model is presented. It takes into account the effect of stress state on damage conditions as well as on evolution equations of damage strains. Different branches of the respective criteria are considered corresponding to various ductile damage and fracture mechanisms depending on stress state. New experiments with the two-dimensionally loaded H-specimen have been developed covering a wide range of stress triaxialities and Lode parameters in the tension, shear and compression domains. These tests are driven under different non-proportional loading paths. Formation of strain fields in critical regions of the specimens is recorded by digital image correlation technique. In addition, scanning electron microscope analysis of the fracture surfaces clearly shows various failure modes corresponding to these loading conditions. Furthermore, results of corresponding numerical simulations are discussed showing good agreement with available experimental data and are used to reveal stress states in critical specimens areas leading to different fracture modes.