Finite element crack closure analysis of a compact tension specimen

Crack closure behaviour of a compact tension (CT) specimen subjected to a constant amplitude cyclic mechanical load, with load ratio R = −2 and the maximum load approaching and exceeding the yield strength based limit load of the specimen, has been examined by performing large strain elastic–plastic finite element (FE) crack growth analyses assuming kinematic hardening. Results from static analyses show that the near crack tip stress and plastic strain fields do not change significantly with further loading after crack closure takes place. Results from crack growth analyses show that the crack closure type depends on the maximum stress intensity factor (SIF) and the crack tip constraint conditions, and that the crack opening/closing loads can be correlated by the maximum SIF, for given crack tip constraint conditions (plane stress/strain). The equation given in the R5 procedure for the crack closure factor, q0, is conservative compared with the results obtained from the FE simulation.