Unified definition of stress intensity factors at a sharp three-dimensional jointed corner

Abstract

In the manufacture of electronic devices and MEMS, a wide variety of materials are jointed. For light-weight automobiles, CFRP materials are jointed with metallic materials. In these products, jointed interfacial corners are singular stress points, and sometimes fractures occur from such corners. Evaluating the severity of the singular stress field is important to protect these corners from fracture. In our previous studies, we proposed a definition of the stress intensity factors (SIFs) of two-dimensional (2D) jointed interfacial corners. We can use this SIFs formula to evaluate the singular stress field around a jointed interfacial corner with a smooth edge front in a three-dimensional (3D) object. However, fractures sometimes occur from sharp 3D jointed corners. In our previous paper, we proposed a numerical method for calculating the scalar parameters that describe the singular stress fields around sharp 3D corners. In this study, we propose a unified definition of SIFs at sharp 3D jointed corners between anisotropic dissimilar materials. The definition is compatible with the SIFs of 2D corners, of interfacial cracks and of cracks in uniform material. Furthermore, the proposed SIFs can describe the singular stress along any directions around a sharp 3D jointed corner.

Keywords

• three dimensional sharp corner
• jointed anisotropic dissimilar materials
• eignevalue
• eigenfunction
• scalar parameters
• stress intensity factor