“…The penny-shaped crack is assumed to have internal pressure applied to its surface. The penny-shaped crack problem subjected to internal pressure has been studied by many researchers (Aizikovich et al, 2015(Aizikovich et al, , 2010(Aizikovich et al, , 2009Lowengrub and Sneddon, 1974;Sakamoto, 2003;Sakamoto et al, 1999Sakamoto et al, , 1989Selvadurai, 2000;Sneddon, 1946) because the problem is equivalent to the essential crack problem of elastic materials subjected to a uniform axial stress according to superposition principle for theory of linear elasticity. The reason of considering the crack subjected to internal pressure is that the crack problem can be formulated as a mixed boundary value problem (Selvadurai, 2000).…”