Evaluation of ductile fracture toughness for Mode I cracks subject to three-dimensional constraint conditions

Abstract

Evaluating the properties related to the fracture mechanics and behavior of cracked structures is pivotal in structural integrity analysis. Accurate theoretical predictions and experimental methods for determining fracture toughness are significant in advancing the fracture strength theory of ductile materials and addressing fracture-related issues in such structures. This study developed models that reflect the dimensionless relationships among load, J-integral, maximum principal stress, and stress triaxiality for Mode I cracked specimens under three-dimensional constraints. These models are developed for ductile materials conforming to the Ramberg–Osgood law based on energy density equivalence and finite element analysis. Combined with the critical fracture criterion under high constraints, an effective method for quantitatively evaluating the fracture toughness of Mode I cracks under three-dimensional constraints was established. Notably, the trends observed in the derived critical J-integral vs. thickness relations align with conventional fracture test results. This research can aid in the accurate predictions of the fracture behavior for ductile structural materials under differing levels of crack tip constraint.