Sensitivity of Material Parameters in the Finite Element Computation of Microvoid Nucleation and Growth

A suitable range of microvoided material parameters is defined to perform a set of finite element computations. The sensitivity analysis is focussed on nucleation and growth of microvoids; the related modifications on microvoid volume fraction, effective plastic strain, hydrostatic stress, dimensions, and load are given through two reference models, the tensile test of a single axisymmetric Q4 element and the upset of a clamped cylinder. It is shown that refined analysis requires the determination of four supplementary material parameters, the initial microvoid volume fraction, the effective plastic strain at incipient nucleation, the potential nucleated microvoid volume fraction consistent with the inclusion volume fraction and the Gaussian standard deviation of inclusions distribution. Nevertheless, for large plastic strain occurrences, an accurate identification of the effective plastic strain at incipient nucleation and the standard deviation of inclusions distribution parameters is not necessary.