Influence of cyclic softening on the energy release rate of an edge crack under simple tension

Prior to the advent of finite element analysis for nonlinearly elastic materials at finite strains, the problem of computing the mechanical fields surrounding the tip of a crack in an elastomer was considered completely intractable (Gent and Mars 2013). This limitation, along with recognition that the stress-concentrating power of the crack tip is responsible for crack growth, inspired Rivlin and Thomas (1953) to develop an energetic theory for the analysis of cracks, following Griffith’s original concept (Griffith 1921). The approach considers the supply of energy associated with growth of a crack, and it avoids the need to understand crack tip fields in detail. It has proven so elegant and powerful that it has been widely adopted into practice. For a general overview of fracture mechanics in elastomers, see Lake (2003) or Thomas (1994).