Photo elastic analysis of stress intensity factors at notches

Simulated cracks from three notch geometries were analysed using two dimensional photoelasticity. The specimens were manufactured from epoxy-resin sheet (CT1200) and the notches machined using a diamond impregnated saw. The notches were semi-circular, U-shaped and V-shaped and the crack length was varied up to 0.6 of the specimen width. The specimens were subjected to pure Mode I loading and the fringe patterns used to calculate the Mode I stress intensity factor. A previously suggested notch correction term gives the ration of the stress intensity factor of a notched to an unnotched specimen. The correction term was determined for all three notches geometries and all crack lengths and the experimental data compared to a previously suggested empirical equation and Finite Element (FE) results. The three sets of results compared well although the FE results were closer to the empirical equation than the photoelastic results. The notch correction factor provides a simple but effective way of calculation stress intensity factors within notches.