Crack Closure Effects in a Cracked Cylinder Under Pressure

Abstract

The circumferential stress varies through the wall thickness when a cylinder is subjected to internal or external pressure. Internal pressure will induce tensile circumferential stress while external pressure compressive stress, in terms of the thick-walled cylinder theory [1]. The resultant stress due to the synergetic contribution of internal and external pressure may be tensile at the inner surface and compressive at the outer surface or vice versa in some cases, depending on the load levels, which would lead to crack-face closure at the compressive edges when the cylinder contains an axial crack. Historically, crack problems in shells were formulated in terms of either the classical theory [2] or the transverse shear theory [3], which were all based on the linearized shallow shell theory [4]–[6]. However, one deficiency of these solutions is that the crack face interpenetration or overlap was allowed at the compressive edge when a bending load was involved, which is physically unrealistic. In reality, crack-face closure on the compressive edge may occur when a shell or plate containing a through-the-thickness crack is subjected to bending load. The present research is aimed to develop a formulation for the determination of stress intensity factor for a cylinder containing an axial crack, which incorporates the effect of the crack-face closure.