Finite element formulations for fracture mechanics

The paper describes a finite element method technique to deal with the determination of strain energy release rates for situations with initial strains. The technique, called Overlay Method, has been calibrated for a linear elastic fracture mechanics situation, based on the classical Griffith Energy Postulate. For elastoplastic fracture mechanics the overlay method does not solve the problem around the ambiguity of the Extended Griffith Energy Balance, which has to be solved by artificial devices. No numerical results can be presented yet in this field. (author)