Experimental and numerical study of the interaction between dynamically loaded cracks and pre-existing flaws in edge impacted PMMA specimens

Dynamic fracture tests are carried out for four groups of hole-containing edge impacted PMMA specimens. The crack growth velocity, crack path, and dynamic toughness are extracted from the experiments using high-speed photography and digital image correlation. The importance of the interaction between the in-coming stress wave and the pre-existing hole is revealed and analyzed. We found that the location and size of the pre-existing holes have a significant effect on the rate and spatial distribution build-up of strain energy near the crack tip due to wave scattering effects from the holes. A micromechanical damage model is calibrated to the experimental data from two of the specimens' designs and evaluated for its predictive capabilities using the other experimental configurations. The studied model is shown to be in reasonable agreement with the experimental data, and its limitations are discussed.