Validation of a FEM-Based Method to Predict Crack Initiation from Arbitrary-Shaped Notches

In this paper, specimens that contain cavities are tested and the critical force for crack initiation is compared to predictions made by the Coupled Criterion (CC). First, the material parameters Young’s modulus, Poisson’s ratio, fracture toughness, and critical stress are calibrated with tensile tests of three specimen shapes. Then, the critical force and crack initiation position are predicted for three other specimen shapes, called validation specimens. The predictions made by CC use stresses and incremental energy release rates that are computed by the Finite Element Method (FEM) and the Scaling Law based Meta Model (SLMM+AC). The predictions are validated against the tensile test results of the validation specimens. A Monte Carlo approach is used to compute prediction intervals for the critical force to make a statement about the quality of the predictions. The position of the crack initiation was predicted accurately, but the predicted critical loads deviated from the measured load up to 25%.