A Failure Mechanism of Pressure Vessels from Filament-wound Hoop Layer

Abstract

This article studied a possible mechanism of a failure from a thick hoop layer of a filament-wound rocket motor case with long cylindrical portion analytically and numerically. The hoop-wound fibers at the cylindrical portion was slightly inclined from the circumferential direction as a finite width prepreg tape was wound without overlapping or gap by alternately feeding in forward and backward direction. Fiber stress concentration in the hoop layer due to possible damage states was assessed through analytical studies and a rough estimate of the stress concentration was given by explicit functions. The possible damage consisted of transverse cracks slightly inclined from each other and debonding of the interface between the hoop layer and the base layer. The approximate analytical solution agreed well with the numerical results in spite of simplification. The results could show the possibility of stress enhancement due to damage in the thick hoop layer made of two slight inclined fibers and important guideline for the design of filament winding pressure vessels.