Figure 1. Schematic of brittle layer of thickness d and modulus E_C on a compliant substrate of modulus E_S, depicting sphere indenter of radius r_i. (Specimen radius r_c in general relation Eq. 1a is effectively infinite in the flat layer structure depicted here.) Damage modes: surface cone cracks (C); quasi-plastic yield zone (Y); inner-surface flexural radial cracks (R).