Figure 2.

A stack of unglazed ceramic tiles (simply piled on top of each other in (a) and intercalated with lattice layers 0.3 mm thick in (b)) were fractured using a vertical wedge-shaped stainless indentor in a quasi-static test (a Beta 100 electromechanical testing machine from Messphysik was used). The photographs provide an intuitive explanation of how a folded structure can result from a stack of layers, each behaving as a plate which is broken with a localized bending eventually resulting in a crack.