DETERMINATION OF DYNAMIC RESPONSE AND DYNAMIC FRACTURE TOUGHNESS (K//I//d( sigma ) OF DCB MODEL UNDER STEP LOADING.

The DCB model is an universal model often used in dynamic fracture mechanics. Particularly, it has found wide application in experimental research and numerical analysis of dynamic crack propagation and arrest. To the author's best knowledge, there is no paper available in the open literature concerning dynamic crack initiation using this model and the dynamic response of this model under the step loading. The contributions of this paper are as follows: (1) the dynamic stress intensity factor of DCB model with different crack lengths are calculated under step loading by using the distorted isoparametric element method; (2) the pin displacement, the dynamic stress intensity factor and dynamic energy release rate are formulated approximately; (3) a simple and available method to determine the initial dynamic fracture toughness by using the DCB model is given; and (4) this paper points out that the bending criterion of crack propagation, given by Z. J. Bilek and S. J. Burns, holds true only if the crack length is much greater than the height of DCB model.