DAMAGE OCCURRENCE UNDER DYNAMIC LOADING FOR ANISOTROPIC STRAIN-RATE SENSITIVE MATERIALS

A damage model is integrated into the explicit finite element framewor k to predict the damage evolution which occurrs under dynamic loading in the crash or stamping process. This damage model is based on the de scription of the growth, nucleation and coalescence of the microvoids. The microvoid growth is related to the plastic incompressibility equa tion. The microvoid nucleation is controlled by either the plastic str ain or stress. The microvoid coalescence is described by a specific fu nction. This damage process leads to the progressive loss of the struc tures stress carrying capacity. The ductile fracture occurs once it ha s vanished. The model is adapted to take the material behaviour anisot ropy and damage anisotropy into account. The sensitivity of the damage evolution under dynamic loadings in the case of porous strain rate se nsitive material is analysed using single tensile tests. Static and dy namic tensile tests of a notched specimen are performed. Influences of the strain rate and the shape of specimen on the failure mode and los s of the structure's stress carrying capacity are shown.