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Interfacial Crack-tip Constraints and J-integrals in Plastically Hardening Bimaterials under Full Yielding

완전소성하 변형경화 이종접합재의 계면균열선단 구속상태 및 J-적분

  • 이형일 (서강대학교 기계공학과) ;
  • 김용범 (서강대학교 대학원 기계공학과)
  • Published : 2003.07.01

Abstract

This paper investigates the effects of T-stress and plastic hardening mismatch on the interfacial crack-tip stress field via finite element analyses. Plane strain elastic-plastic crack-tip fields are modeled with both MBL formulation and a full SEC specimen under pure bending. Modified Prandtl slip line fields illustrate the effects of T-stress on crack-tip constraint in homogeneous material. Compressive T-stress substantially reduces the interfacial crack-tip constraint, but increases the J-contribution by lower hardening material, J$\_$L/. For bimaterials with two elastic-plastic materials, increasing plastic hardening mismatch increases both crack-tip stress constraint in the lower hardening material and J$\_$L/. The fracture toughness for bimaterial joints would consequently be much lower than that of lower hardening homogeneous material. The implication of unbalanced J-integral in bimaterials is also discussed.

Keywords

Bimaterial;Plastic Hardening Mismatch;J-integral;T-stress;Biaxiality;Constraint;Finite Element Analysis;Modified Boundary Layer Formulation;Full Specimen;Slip Line Field

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