Failure modelling in finite element analyses: Random material imperfections

A phenomenological failure model has been developed where the material is assumed to contain initial material imperfections that influence the material strength only through the largest imperfection. The imperfections are randomly distributed and characterized by material imperfection density functions. In a first approach one type of imperfection is assumed with an exponential imperfection density function. The model parameters are optimized, using results from a deterministic finite element analysis, to match a target function representing the probability of failure in a tensile test. The developed model manages to reproduce this data well.