Plastic J-integral calculations using the load separation method for the double edge notch tension specimen

The load separation method was used to determine the plastic work factor (ηpl) for the double edge notch tension (DENT) geometry for power-law hardening materials. The resulting expression for ηpl compares favorably to the results of Rice, Paris, and Merkle. The results were also compared to ηpl calculated from the plastic J results in EPRI Handbook NP-1931 and substantial differences were noted. A dependence on gage length was identified in the load separation results which indicate a gage length to half-width ratio of at least 3 is required to ensure that all of the plastic displacement is fully sensed and that ηpl is independent of gage length. Additionally, a coupling term between crack size and material hardening exponent was identified in the geometric load separation function G.