Fracture analysis of composite pressure vessel using FEM

Abstract

A finite element-based numerical method is applied to predict the possibility of propagation of existing delamination/patch in a filament wound composite pressure vessel in this work. Strain energy release rates (SERRs’) in the three principal modes are predicted along the circumference of delamination for two different load cases, i.e., internal pressure load when two diametrically opposite patches are existing in the nozzle end side dome portion, and combined load due to thrust and bending when a patch is located in the nozzle end side skirt region of the composite pressure vessel (CPV). The problem is modeled in ANSYS software and a three-dimensional finite element approach in association with virtual crack closure technique (VCCT) is used to analyze the fracture behavior of the CPV under two load cases as stated. In both the load cases, SERR is found to be maximum at the bottom side of the patch, Mode-I being dominant under pressure load, and Mode-II in axial load. Delamination growth is observed at 26.5% of applied pressure in Case-1 and 57.5% of axial load in Case-2. This fracture analysis approach can be extended to composite structural components in defense and aerospace applications.