Effects of Thickness and Winding Angle of the Laminate on Internal Pressure Capacity of Thermoplastic Composite Pipes

Abstract

Thermoplastic composite pipes (TCPs) are increasingly used to transport hydrocarbons and water in the oil and gas industry due to their superior properties including corrosion resistance, thermal insulation, light weight, etc. The cross-section of TCPs generally consists of three layers: inner liner, composite laminate, and outer jacket. Three layers are bonded together and form a solid-wall construction. Inner liner and outer jacket made of thermoplastic polymer provide protective barriers for the laminate to against the inner fluid and outer environment. The laminate is constructed by an even number of helically wounded continuous fiber reinforced thermoplastic composite tapes. In this study, mechanical behaviors of a TCP under an internal pressure were investigated by using analytical and finite element analysis (FEA) methods. The analytical method which is based on the three-dimensional (3D) anisotropy elastic theory can take account of non-uniformly distributed stress and strain through the thickness of the pipe wall. FEA models were setup by using the software ABAQUS to predict the stress distribution of the pipe. 3D Tsai-Wu failure criterion was used to predict the maximum internal pressure of the pipe. Effects of some critical parameters, such as the winding angle of composite tapes and the number of reinforced plies, on the internal pressure capacity of TCPs were studied. Results obtained from the analytical and FEA methods were fairly agreed with each other, which showed that with the increasing of the number of reinforced plies the internal pressure capacity of a TCP gradually increases and approaches to an extreme value. In addition, the optimal winding angle which results the maximum internal pressure is not a constant value, instead, it varies with the increasing thickness of the laminate layer. This study provides useful tools and guidance for the design and analysis of TCPs, and is currently under validation through experiments.

Stress Distribution and Fracture Toughness of Underground Reinforced Plastic Pipe Composite

“…Moreover, the effects of the layup and fiber orientation were studied. Another finite element study [ 11 , 12 ] investigated the effect of thickness, winding direction, and the number of fabric plies of composite cylinders under internal pressure on the characteristic mechanical properties using the analytical finite element method. The hoop stress distribution or the circumferential thickness tensile strength was calculated numerically and experimentally using a split-disk test method [ 13 ], which was based on a progressive damage model through finite element analysis of a cracked disk.…”