Ductile damage evolution under cyclic non-proportional loading paths

The characterization of ductile damage evolution, and its description, have been the object of extensive research in the continuum damage mechanic field. Starting from the pioneering works of Lemaitre (1985), Gurson (1977), Rousselier (1987), many different models have been developed. In detail, the stress triaxiality and the Lode angle parameters have been identified as the two main variables that affect the material ductility. The literature offers a great number of investigations under monotonic loading conditions, however, a proper characterization of the damage evolution under cyclic loading or non-proportional loading is still missing. In this paper, an unconventional coupled elastoplastic and damage constitutive model with a Mohr-Coulomb failure criterion (Bai and Wierzbicki, 2010) is presented. The ductile damage evolution law is modified in order to consider the damage evolution under non-proportional loading conditions. The idea is to compare the damage evolution of a steel bridge column subjected to three different non-proportional loading paths in order to identify the loading condition that compromise the structural integrity.