3-DIMENSIONAL FEM STRESS-ANALYSIS FOR BONDED DISSIMILAR PLATES WITH VARIOUS THICKNESSES

The distributions of stress induced by an applied stress ob in five jo int plate specimens (copper/silicon nitride) with different thicknesse s were calculated using three-dimensional (3-D) FEM stress analysis an d the results were compared with those obtained using two-dimensional (2-D) FEM stress analysis. Along the longitudinal center line perpendi cular to the interface on the surface of the specimen, the 3-D FEM cal culation predicted a maximum stress of approximately 1.3 sigma(0) in t he interfacial region in the silicon nitride, with a minimum stress of 0.9 sigma(0) appearing in the copper. On the other hand, the 2-D FEM predicted only slight change in the stress in the interfacial region, giving a value close to the applied stress sigma(0). The maximum stres s decreased more rapidly with decreasing thickness of the specimen, an d the stress value agreed more closely with the value calculated by th e 2-D FEM as the distance from the interface increased.