The effect of geometry on fracture strength measurement using DCDC samples

The fracture behavior of poly(methyl methacrylate) (PMMA) is studied using double cleavage drilled compression (DCDC) experiments. Increasing sample thickness is found to increase the stresses required to propagate long cracks. Crack surface features show a correlation with regimes of crack growth. Decreasing hole size leads to significant inelastic deformation during testing and, after unloading, the formation of new stress-relieving cracks at the central hole. A computational model using the experimental data estimates the critical stress intensity factor of PMMA to be 0.6–0.75 MPa m½. Photoelastic observations are used to compare experimentally observed and simulated stress distributions.