Failure and debonding of thin circular and square tiles (islands) bonded with a compliant interlayer

Abstract

This paper presents analytical solutions for the stresses in circular thin films bonded to a substrate with a thin compliant interlayer. The axisymmetric results are shown to be an excellent approximation for square tiles (islands), provided one defines an effective diameter equal to the average of the square's diagonal and width. An analytical result is also presented for the energy release rate associated with convergent circular delamination cracks (from the outer edges of the tile inwards). These solutions are used to generate regime maps that indicate active failure mechanisms (tile yielding, interlayer yielding and delamination) as a function of constituent properties and tile size. These regime maps clearly indicate acceptable tile sizes and/or the required material properties to avoid all modes of failure.