Mixed hardening constitutive model of steel considering damage evolution

For more accurately simulating the metallic material degradation induced by cyclic load, elasto-plastic material model considering damage evolution and mixed hardening is presented based on the large strain elasto-plastic theory and the damage mechanics theory. Bi-linear mixed hardening model and Lemaitre's damage model are adopted. Making use of the material properties from tensile experiment, an approximation method for calculating the damage material parameters is presented. Using the user programmable features (UPFs) of ANSYS program, the material routine is developed and incorporated into ANSYS program. The hysteretic tests of a thick ring and steel members are simulated using the material model. The hysteretic curve and the crack initiation life from FE (finite element) analysis agree well with the results from the tests.