Effect of Tangential Loading on Critical Conditions for Radial Cracking in Brittle Coatings

Abstract

Results of Hertzian contact tests investigating the effects of superposed tangential loads on the critical conditions for radial cracking at the undersurfaces of brittle coatings on compliant substrates are reported. It is demonstrated that these effects are secondary, so that conventional normal indentation remains an appropriate test procedure for characterizing this highly deleterious mode of coating fracture under a wide range of complex loading conditions.