Prediction of progressive fracture of SMC by application of bridging laws

Experimentally obtained load vs. displacement curves from compact tension tests (CT) of two different SMC materials are analyzed in this paper. Three different CT specimen geometries are considered. Progressive fracture is attained in all tests. This gives rise to a long post-peak tail part in the load vs. displacement curve. By implementing bridging laws and volumetric stiffness degradation of bulk SMC in an FEM model we are able to reproduce the two larger geometries considered (50 mm×50 mm and 100 mm×100 mm) with high accuracy. Discrepancy between model predictions and experiments for the smallest geometry considered (20×20 mm) was observed. This was due to premature compressive failure on the side opposite to the CT specimen precrack. The successful use of bridging laws strongly suggests that they are intrinsic properties governing fracture behavior of SMC materials. The fact that our bridging laws were determined based on independent tests on different specimen geometry is adding strong arguments to preceding conclusion.