Practical method for analyzing singular index and intensity of singular stress field for three dimensional bonded plate

In this paper, the practical analysis methods are proposed for analyzing the singular index and the intensity of singular stress field (ISSF) at the vertex of the interface in the three dimensional (3D) bonded plate. The analysis methods focus FEM stresses at and around the vertex. The singular index is determined from the FEM stress ratio at the vertex obtained by performing FEM analyses on the finely and coarsely meshed models. Then, the ISSF is determined by the ratio of the average FEM stresses at and around the vertex obtained by performing the FEM analyses on the reference and unknown models under the same mesh pattern. The validity of the present methods was examined by the plane strain bonded plate and 3D bonded plate in the literature. It was found that the present methods for the singular index have the same accuracy as the FEM eigenvalue analysis. The asymptotic solutions with the singular index and ISSF by the present method correspond to FEM stress distributions. Since the ISSF by the body force method (BFM) is used as the reference solution, the present method for ISSF has the same accuracy as BFM. Moreover, the critical ISSF values were calculated in the experimental results of the butt joints with various adhesive thicknesses. In the case of the ductile epoxy adhesive, it was shown that the critical ISSF at the vertex by 3D model was more constant against the thickness than that by 2D model. The result is quite different from that of the brittle epoxy adhesive and can be never obtained by 2D model.2018 International Conference on Material Strength and Applied Mechanics (MSAM 2018), 10–13 April 2018, Kitakyushu City, Japa