Finite element crack propagation calculation using trial cracks

We present a method to perform finite element calculations for crack propagation problems with arbitrary crack directions in two dimensions. The crack direction (angle of propagation) is determined by inserting small “trial cracks” at the crack tip and measuring the energy release rate when these trial cracks are opened. Several finite element calculations are performed for each crack length increment. In this way, the energy release rate can be calculated even in cases where other methods fail. After explaining the algorithm, it is applied to two test problems: a three-point bending specimen with central or offset initial crack and crack propagation near an elastic inclusion.