Finite element and fracture mechanics analyses of filament-wound pressure vessels with thin metallic liners

This dissertation provides the theoretical background and concept for analyzing the filament-wound pressure vessels with thin metallic liners. The thin metallic liner is serving mainly as a permeation barrier to hold liquid or gas, while the composite is sized to carry majority of the pressure loads. The bilinear material model is selected to simulate the material stress-strain curve which governs the metal linear behavior. An equivalent Poisson\u27s ratio is proposed to take into account the apparent change of Poisson\u27s ratio when liner stress exceeds the yield strength of material. The subjects investigated in this dissertation are classical lamination theory, quadratic failure criterion, bilinear material model, finite element analysis for axisymmetric solids, and linear elastic fracture mechanics. The objective of this dissertation is to establish a rational analysis procedure for filament-wound pressure vessels with metal liners. Four sample cases are analyzed to demonstrate the capabilities of the developed finite element program FEASY4ND in solving the axisymmetric shell problems. The cases investigated include the parametric study on Poisson\u27s ratio, the thick-walled and thin-walled sphere analyses, and analysis of a sample filament-wound pressure vessel with a thin metallic liner. The filament-wound pressure vessel is analyzed at proof, operating, and design burst pressures. The liner cycle life is calculated based on the principle of linear elastic fracture mechanics. The effect of crack geometry (a/2c), compressive effectivity factor f, proof pressure, operating pressure, and edge effect on the liner cycle life are also investigated. An empirical formula for conservatively predicting the liner cycle life of the sample pressure vessel in terms of the ratio of operating and proof pressures, and compressive effectivity factor is derived using least-squares curve-fit technique