Effect of material failure criteria on collision behavior of metro vehicle end structures

This study comprehensively analyzes the failure behavior of metro vehicle end structures (VESs) during collisions, using the common material SUS301L-MT in a stainless steel metro and its VES as the research object. First, constitutive and failure tests are performed on the material, the macro-micro characterization of its mechanical properties is performed, and the failure strains and morphologies under various stress states are obtained and discussed. Subsequently, two failure criteria, Von Mises (VM) and Generalized Incremental Stress State Dependent Damage Model (GISSMO), are calibrated and established. Finally, the crashworthiness evaluation indexes of the VES are defined, and vertical offset collisions of metro VESs for different speed levels are numerically analyzed. The results show that the stress triaxiality significantly affects the failure strain of stainless steel SUS301L-MT, with the maximal difference for different stress states reaching 51.10%. SUS301L-MT stainless steel exhibits strain-rate strengthening and yield hysteresis effects. Overall, the numerical results for the VM criterion are worse than for the GISSMO criterion, which more accurately describes the collision behavior of metro VESs under complex stress states.