A study of dynamic caustics around running interface crack tip

Based on the first invariant Of stress singular field in the vicinity of ru nning tip of an interface crack, mapping equations of the caustic curve on the reference plane and the initial curve on the specimen plane are develop ed. The dynamic caustics are analyzed for the crack propagating along;the i nterface between two bonded dissimilar materials. The variation of;the caus tic configurations is shown with the velocity change of the running crack a nd the ratio change of the stress intensity factors. Two characteristic dim ensions are proposed that are not only practically measurable from optical caustic contours but also suitable to represent the behavior of transient c austics.