Theoretical and Numerical Study on Disappearance of Free-Edge Stress Singularity by Inserting an Interlayer to Bonded Dissimilar Materials

Abstract

The free-edge stress singularity usually develops near the intersection of the free-surface and the interface for the bonded dissimilar materials. When two materials are bonded by using an adhesive, an adhesive layer may develop between two bonded materials. To defuse the residual stress which develops because of the difference of the coefficient of thermal expansion, an interlayer may be inserted between two materials. On the other hands, the free-edge stress singularity disappears for certain pair of materials. In this study, the disappearance of free-edge stress singularity by inserting the interlayer to the bonded dissimilar materials for which free-edge stress singularity develops were investigated theoretically and numerically. It was found that the free-edge stress singularity disappeared by inserting a proper material to the bonded dissimilar materials. It was theoretically shown that there existed combination of material parameters of such an interlayer. Stress distributions on the interface of bonded dissimilar materials with an interlayer were calculated by using the boundary element method, and disappearance of free-edge stress singularity was confirmed numerically. When the interlayer was very thin, stress distribution near the intersection of the interface and free-surface was controlled by the free-edge stress singularity of the bonded dissimilar materials without the interlayer.