Brian R. Lawn, K S. Lee, Herzl Chai, Antonia Pajares, D K. Kim, S Wuttiphan, I M. Peterson, X Z. Hu
A conceptually new approach to the design of brittle coating structures on soft substrates, based on prevention of crack initiation rather than on customary crack containment, is outlined. Concentrated loads produce two competing coating fracture modes classical cone cracks initiating from the upper coating surface; and less well documented (but more insidious) radial cracks initiating from the lower coating surface. Analytical expressions for critical fracture loads are given in terms of basic geometrical and material parameters. The analysis provides simple design guidelines to optimal coating damage resistance, with predictions that run somewhat counter to conventional fracture mechanics.