Abstract:Energy release rate is an important parameter characterizing fracture behaviors of materials. In classic fracture mechanics, only formulae for the energy release rate of linear elastic cracked structures are given by compliance method, especially limited to fixed loading or displacement boundary conditions. Moreover, the fracture toughness and toughening mechanism of hyperelastic materials such as biomaterials and polymer (rubber-like materials) are attracting more and more attention of researchers. The paper aims to develop general formulae to calculate the energy release rate of nonlinear elastic structures under arbitrary loading conditions, and these formulae also facilitate to evaluate the stability of crack growth. During the deducing process, several important but misleading concepts are further clarified.