Structural response validation of composite cylindrical pressure vessels using FEA

Abstract

Cylindrical pressure vessels constructed using filament winding technique are a good example of the advantages that fibre-reinforced composite materials offer over common structural materials on a specific/unit weight basis. The high specific properties of composite materials over metals can reduce the weight of pressure vessels with a high potential for applications in submarines and ROV/AUV. An innovative method for the optimisation of composite cylindrical structures is through simulation of the pressure vessel response using as parameterised finite element model. In this paper the effect of boundary conditions has been analysed for a cylindrical pressure vessel of carbon-epoxy composite material subjected to internal pressure. For the said study, a parametric Finite Element model using an 8 noded layered solid brick element has been created in the finite element analysis software ANSYS using its Parametric Design Language features. The elasticity solution for a single layer circular tube has also been presented in reference to the works of Herakovich and Pindera towards validation of the numerical model. Pressure vessel finite element models, with different boundary conditions have been used to study convergence in comparison to the exact solution. A comparison of the through thickness distribution of stresses from different finite element cylindrical models in ANSYS against the exact solution for a composite tube under internal pressure have been presented for the validation of the numerical model and proposed boundary conditions. It has been demonstrated that only one element in circumferential direction using displacement coupling conditions at the boundary is sufficient, which would significantly enhance the computational efficiency of a structural analysis and make these models computationally efficient even for a non-linear analysis with axi-symmetric loads for both static and dynamic cases.