Constant strength design of filament wound thick-walled cylindrical structure considering variation of fiber volume content

In filament wound thick-walled cylindrical pipe or vessel, the winding tension makes stress state of fiber layer change, which forms a non-uniform structure through thickness. According to the analysis of stress state and constitutive relation of fiber bundle in winding process, the relationship between the fiber volume content and the stress state was obtained. Based on the orthotropic constitutive relations and discrete superposition method of a double layered cylinder model, a calculation method to determine the residual tension for given winding tension in filament wound thick-walled cylindrical structure was established, where the distribution of fiber volume content through wall thickness was calculated for a constant winding tension. Using Tsai-Wu failure criteria, the strength of filament layer was investigated in thick-walled cylindrical structure with non-uniform fiber volume content. It is found that winding process makes the fiber volume content and strength of inner layer higher than those of the outer layer, where the influence of non-unform material property should be considered in analyzing and designing of filament wound thick-walled cylindrical structure. Uniform distribution of strength through thickness can be achieved by design of variational winding tension.