Fracture analysis of A6063-T6 materials used as liner of composite overwrapped and type I pressure vessels under internal pressure

Abstract

Burst pressure is used as a safety design limit for a pressure vessel. This research aimed at finding burst pressure of three models of cylindrical pressure vessels, i.e. a) composite overwrapped pressure vessel (COPV) with an aluminum liner, b) aluminum pressure vessel with the same thickness as the liner of COPV, and c) aluminum pressure vessel with the same thickness as the total thickness of COPV. Non-linear finite element simulations,were used as a numerical tool to find stress, strain, and deformation of the cylinder. It was found that the aluminum material used as an aluminum liner of COPV has a higher burst pressure up to 55 MPa, while burst pressure of the other two aluminum cylinders only reaches 11.6 and 17.6 MPa. These results show good correlations with the theoretical calculation, which is calculated by using Faupel formulae and the Barlow Equation. In order to investigate the effect of using the CFRP layer on the severity of the crack defect in the aluminum liner, fracture analysis was held to find the stress intensity factor (SIF) along the crack front of a semielliptical crack. It was found that using CFRP layers, the stress intensity factor and energy release rate are reduced to 64.84% and 87.09%, respectively.