ABSTRACT
The Fracture Mechanics approach has gained wide recognition, and has matured into wellaccepted methods and tools. Rivlin and Thomas (1953) and Thomas (1955) proposed the tearing energy as a criterion for characterizing mechanical conditions at a crack tip. The criterion found immediate application in studies of what magnitude of loading would cause a crack to tear, and what would be its rate of tearing (Greensmith and Thomas 1955). It was also applied to cases involving dynamic loading (Thomas 1958). Early studies focused on fatigue crack growth occurring with the load fully relaxed between each application. Later, Lindley (1973) looked into the effects of non-relaxing cycles. The advent of Finite Element Analysis enabled the energy release rate to be evaluated for real components and structures under complex loading (Lindley 1972), and the approach has been implemented through a variety of schemes (Parks 1977, Shih et al. 1986, Shivakumar et al. 1988, Steinmann 2000, Mueller and Maugin 2002), and is commercially offered in several finite element codes.
