Effect of punch and specimen dimensions on the confined compression behavior of S-2 glass/epoxy composites

The behavior of composite materials under transverse loading is often characterized using quasi-static experimental methods. A complete characterization requires experimentation for a range of specimen and impactor dimensions, necessitating a sizeable test matrix. However, if dimensional effects on specimen damage behavior can be understood, the number of tests required can be reduced. The present study considers confined compression testing of an S-2 glass/SC15 resin composite under quasi-static loading to understand damage initiation and propagation during penetration. A test matrix of 29 punch–specimen combinations was tested to determine the fracture behavior and applied load at failure. A finite element (FE) model of the experiments was also created to study the internal stress distributions. Characteristic fracture angles and applied stresses at failure were observed to be independent of punch–specimen dimensions. However, varying the dimensions of the punch and specimen was found to change the behavior of the internal stresses. Various failure criteria were evaluated using the numerical stress distributions to predict damage initiation. A Mohr–Coulomb compression–shear interaction on the fracture plane was found to best explain the observed experimental behavior.