13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- 3. Numerical experiments 3.1. Variation of intensity of stress singularity K1φφ with respect to radius of curvature R In this study, a structure made by resin with silicon plate inclusion shown in Fig.3 is employed as a numerical model. Nodal distribution around target area and material properties are shown in Fig.4 and Tab.1. In case of computational model of R=0, order of stress singularity λ at vertex on silicon surface is obtained as 0.436. In this study, the radius of curvature R at vertex of silicon plate is changed as shown in Tab.2. In case that tensile stress, 10MPa, is applied to top surface, stress distribution σφφ on surface in silicon plate with respect to angle φ is shown in Fig.5. It is seen that gradient of stress distribution σφφ is almost same for each angle φ. Next, comparison of stress distribution σφφ on silicon surface at angle direction φ=315° is carried out. The result is shown in Fig.6. It is found that stress value decreases with increasing the radius of curvature R and constant stress region of σφφ near point O, i.e., stress singularity disappearance region, increases with increasing the radius of curvature R. Here, in Fig. 6, solid line indicates fitting line by σφφ= K1φφr －0.436. In addition, relationship between intensity of stress singularity K1φφ and radius of curvature R is shown in Fig.7. From this result, it is found that intensity of stress singularity K1φφ almost linearly decreases with increasing the radius of curvature R. Silicon plate Resin Target area 10MPa 6mm 4mm 0.6mm 0.6mm 1.2mm Figure 3. Computational model r φ O R Figure 4. Nodal distribution around target area
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