11 - Crack path selection in adhesively bonded joints

Abstract

This chapter examines the fracture mechanics concepts that influence crack path selection behavior in adhesively bonded joints and reviews a recent study aimed at understanding and predicting crack path selection. The discussion briefly reviews relevant fracture mechanics and interface mechanics theory, illustrates results from experimental studies, and highlights both numerical and analytical modeling efforts. Several fracture mechanics criteria—maximum opening stress criterion, maximum energy release rate criterion, and mode-I fracture criterion. All three criteria are consistent with the mechanics notion that cracks tend to grow perpendicular to the largest tensile stress. These criteria, although developed primarily for cracks in homogeneous materials, can be extended to bi-materials systems such as adhesively bonded joints, coatings, and laminated materials. Specifically, the effects of mode mixity and the T-stress—both of which can be affected by specimen geometry, material properties, loading mode, and residual stress state—are provided in the chapter.