Optimization in Polymer Composite Piping Design

Polymer composite piping that is composed of a fiber reinforcement phase embedded in a continuous polymer matrix is associated with high specific strength and excellent corrosion properties. The fiber reinforcement is often considered to dominate the mechanical performance of composite structures. Consequently, principal design parameters for composite piping are usually associated with the fiber architecture, which in many practical applications has been limited to simple angle-ply configurations. Nevertheless, the function of the polymer phase is not limited to merely providing rigidity to the otherwise pliable fiber architecture. In fact, the often quoted high strength of composites is sustained by a load-sharing mechanism that the matrix enables between filaments. In this manner, the effect of localized flaws and filament damage is mitigated, and only the accumulation of numerous micro damage events leads to component failure. An additional function of the polymer matrix is to prevent ingress of fluid into the composite and possible leakage in pressure-bearing components. The design of composite piping therefore needs to consider a matrix-sensitive damage criterion. In view of variable loading conditions and multi-angle fiber architectures this study investigates design optimization techniques intended to yield better performance in terms of strength and especially fluid permeation resistance.