“…where x ∈ , ω k = 2π k/T , j = 1, 2 and contact area would be unknown beforehand and must be determined as a part of the solution, see, for example, [39,42,43], where the nonlinear effects due to the crack closure were analysed for cracks under time-harmonic loading in homogeneous and heterogeneous elastic materials. Considering this crack face interaction effect for the case of transient impact loading will be the next natural stage of the research.…”