Method for calculating G, GI, and GII to simulate crack growth in 2D, multiple-material structures

• New method automatically calculates G, GI, and GII for growth at any kink angle.
• Cracks respond to material interfaces and many interfaces can join at crack tip.
• Same approach used to investigate crack growth regardless of location of crack tip.
• Complete framework for simulating crack growth through multi-region composite.
• Six examples and a crack propagation simulation demonstrate application of method.

A finite element approach for calculating the energy release rate (G) and individual modes (GI and GII) when simulating crack growth through a two-dimensional composite material is presented. A new mesh-substitution scheme is used with basic fracture mechanics concepts to automatically calculate G, GI, and GII for potential growth along material interfaces and at different kink angles. The method is general and can be used when investigating interface cracks, substrate cracks (i.e., cracks contained in a material region), and substrate cracks with tips touching one or more interfaces. For bimaterial interface cracks, a coupled energy release rate (GI–II) is determined, and complex stress intensity factor components are calculated. A complete crack propagation framework, which includes the developed methods, is presented and then used to simulate crack growth through a composite material.