Multiple cracking of elastic coatings under transient thermal load

A periodic array of cracks in an elastic coating bonded to a homogeneous substrate is considered. The medium is subjected to mechanical loads and/or thermal loads. The problem is formulated in terms of a singular integral equation with the crack face displacement as the unknown variable. In addition to the time-varying stress intensity factors and stresses for various parameters of the problem, the effect of periodic cracking on the relaxation of the transient stress on the coating surface is discussed. Solution techniques for a single elastic layer and an elastic coating bonded to an infinite substrate are given. It is found that, if the crack density attains a saturation value, the transient thermal stress in the medium could be released significantly, suggesting that further cracking is difficult.