Optimization of winding process for composite pressure vessels

Abstract

The winding of composite pressure vessels and pipes is always realized with some pretensioning, and some external loads may be applied. It is important to determine an optimal preload regime that ensures the maximum load-carrying capacity of the vessel subjected to internal pressure. In the present paper the optimal preload distribution is analyzed in the winding process for cylindrical and spherical pressure vessels that are treated as growing viscoelastic bodies subjected to ageing. In the case of cylindrical pressure vessels, an explicit solution for the dependence of the optimal preload intensity on the polar radius is derived for a nonageing material, and an approximate analytical solution is obtained for an ageing ribbon material. The influence of the rheological characteristics of the material on the optimal pretensioning is studied numerically. In the case of spherical pressure vessels, the optimal regime of internal pressure applied during the winding process is obtained that ensures a uniform residual stress distribution over the vessel cross-section. Both ageing and nonageing viscoelastic materials, as well as the optimal loading of a spherical vessel at finite strains, are analyzed. The new solutions obtained and the formulated recommendations are of special practical interest and importance for the optimal design and manufacturing of composite pressure vessels and pipes.