Methods for Energy Release Rate Calculation,

This paper compares four methods for obtaining fracture mechanics parameters from finite element computer programs. Total energy release rate values are obtained using numerical differentiation, crack closure integral, modified crack closure integral, and crack opening displacements. A commonly used method, numerical differentiation of strain energy, does not yield the correct energy release rate when displacement and traction loads are applied simultaneously. The authors found that the relatively new crack closure integral method was preferable. Several test problems showed that, when properly applied, results from numerical differentiation and crack closure integral techniques were within 0.1 agreement. Author