APPLICABILITY OF J-INTEGRAL TO TENSION-SOFTENING MATERIALS

This brief paper addresses the application of the J-integral to fractu re analysis and toughness characterization of quasi-brittle materials, with specific focus on the tension-softening behavior in the fracture process zone. Concern is often raised on the validity of the J-integr al when unloading occurs in the material points along which the J-inte gral contour path traverses, particularly during process-zone growth. This paper clarifies that this concern is misplaced. Whereas the J-int egral contour wraps around the tension-softening line springs of the b ridging elements in the process zone, the material points on the J-int egral contour undergoes elastic loading and unloading. Therefore appli cation of the J-integral to quasi-brittle materials does not violate t he basic tenet of the assumption of nonlinear elastic material behavio r underlying the J-integral theoretical formulation.