Constraint-corrected J-R curve based on three-dimensional finite element analyses

摘要

Three-dimensional (3D) finite element analyses are carried out on single-edge bend [SE (B)] specimens for which the J-integral resistance curves (J-R curves) have been experimentally determined to develop the constraint-corrected J-R curves for the X80 grade pipe steel. The constraint parameters considered in this study include Q_(HRR), Q_(SSY), Q_(SSY_m), Q_(LM), Q_(BM1), Q_(BM2), A_2, h and T_z. The constraint-corrected J-R curves were developed on the basis of the constraint parameters obtained from finite element analysis and experimentally determined J-R curves associated with deeply cracked and medium-cracked SE(B) specimens and validated against shallow-cracked SE(B) specimens. The analysis results indicate that all the constraint parameters considered in this study except Q_(HRR), Q_(SSY), Q_(SSY_m) and Q_(LM) lead to reasonably accurate constraint-corrected J-R curves if the crack extensions are relatively small (≤0.7 mm). For larger crack extensions (≤1.5 mm), the Q_(BM1 -based constraint-corrected J-R curve leads to the most accurate predictions of J among all the constraint parameters considered.