Considerations in Using FEA for Layered Vessel Construction

Abstract

This paper will examine some of the considerations for using finite element analysis when evaluating pressure vessels constructed using the layered-shell construction. Since the layers of the shell interact through contact and at the circumferential welds, these particular aspects are discussed. Special attention is paid to the proper selection of the initial gap between the layers. The use of an elastic-plastic stress-strain curve is also discussed. Since the material model is non-linear, the path-dependency of the loading sequence is demonstrated, including the inclusion of the initial hydrostatic test. The techniques presented will be demonstrated using an example of a typical layered shell pressure vessel. Since the evaluation of this type of vessel is usually undertaken in a fitness-for-service sense, and fatigue is often the primary damage mechanism, the remaining fatigue life of this typical pressure vessel is calculated.