Interfacial crack-tip constraints and J-integrals in plastically mismatched bi-materials

The effect of the T-stress and plastic mismatch on interfacial crack-tip stress under small scale yielding condition is investigated in this paper via detailed finite element analyses. The mismatch in plastic strength/hardening is focused, and plane strain elastic–plastic crack-tip fields have been modeled with modified boundary layer formulation. Plastic mismatches as well as compressive T-stresses in bi-material are shown to affect the interfacial crack-tip constraint substantially. Simple patching of slip-line fields is presented to characterize the interfacial crack-tip stress fields. Effects of T-stress and plastic hardening mismatch on asymmetry of the J-integral for bi-materials, and its implication on interfacial toughness are also discussed.