On mixed-mode fracture of PVC foam

This paper reports on mixed-mode fracture in rigid cellular PVC foam based on experimental and numerical analyses. Experiments were performed on sharp -cracked specimens using the compact-tension-shear (CTS) test loading devic e. Foams of three different densities were tested. The CTS specimen was, in association with a special loading device, an appropriate apparatus for ex perimental mixed-mode fracture analysis. Experimentally-obtained fracture t oughness results show good consistency. K-IC fracture toughness was margina lly different in different directions. The ratio K-IIC/K-IC was found to be between 0.4 and 0.65 depending on the foam density. For mixed-mode loading , Richard's criterion - using experimentally obtained K-IC and K-IIC - was the best in predicting accurately fracture locus and fracture angle. When n o experimental data were used, the maximum hoop stress criterion predicted best kinking angle. The principal strain criterion predicted the best fract ure locus. Fracture boundary curve and kinking angle were best predicted fo r low mode II contribution.