层状陶瓷的材料力和裂纹力评估方法

Abstract

Characteristics of J_far(0), J_far(a), J_far(a)-J_far(0)and J_tip were analyzed for ceramic laminates under bending loads based on the J-integral theory. Here J_far(0) and J_far(a) were the far-field J-integrals corresponding to crack lengths 0 and a respectively. The crack was perpendicular to the interfaces. A basic assumption was that the crack length was small compared with the laminate thickness, and the stress and strain fields in the region far from the crack were little influenced by the crack. Both J_far(0) and J_far(a) were path-dependent, because the lengths of the interfaces enclosed by the path of integration varied with the path. However, J_far(a)-J_far(0) became path-independent when the path was far from the crack. J_far(a)-J_far(0) was seen as a parameter to represent the global driving force for fracture. The purpose is to make the present method available to evaluate the inhibiting or boosting effects of material inhomogeneities on the crack tip driving force by J_tip-(J_far(a)-J_far(0)).