Numerical simulation of the effects of the load multiaxiality and deformation process parameters on the fatigue life of metals

摘要

We analyze well-known experimental data on the effect of the load multiaxiality and the type of deformation trajectory on the process of damage accumulation in fatigue. In the framework of the continuum mechanics for damaged media, we refine the criterion for the governing equations that describe processes of elastoplastic deformation and damage accumulation in structural materials (metals and alloys) under multiaxial nonproportional paths of low-cycle fatigue. The damaged-media model consists of three interrelated constituents: governing relations for the material elastoplastic behavior with the account of the fracture process effects, equations describing the damage-accumulation kinetics, and the strength criterion of the damaged material. In order to provide a quantitative assessment of the governing equations, a numerical simulation of constructing the equi-damaged surfaces was performed, and the results calculated were compared with the experimental data. We investigated the influence of multiaxial stressed state and the type of deformation trajectory on the high-cycle fatigue life of metals. It is shown that the refined version of the governing relations for the damaged media provides adequate description of the main effects of cyclic elastoplastic deformation and damage accumulation under multiaxial stressed state conditions and arbitrary deformation trajectories of the material.