This paper describes the analysis of the mechanical behavior of the reinforced thermoplastic pipe (RTP) under internal pressure. RTP studied in this paper consists of a polyethylene liner, two layers of reinforced tape over wrapping the liner and an outer polyethylene coating. The reinforced tapes, carrying the major part of the loadings, are considered as homogeneous and transverse isotropic. A theoretical model based on the three-dimensional (3D) anisotropic elasticity theory is proposed to study mechanical behavior of RTP. Using ABAQUS, a finite element model is established to predict the mechanical behavior, damage evolution, burst capacity and failure mode of RTP. A failure initiation criteria and material degradation model is incorporated into the ABAQUS as individual subroutine. Model based on plydiscounting material degradation approach is adopted to simulate the damage progression by degrading the local material constitutive coefficients. Theoretical and FE results are presented and compared. Values of burst capacity and failure modes predicted from theoretical and FE simulation show good agreement with the experimental results.
Due to its high cost effectiveness, excellent corrosion resistance, and ease of installation, Reinforced Thermoplastic Pipe (RTP) is now increasingly being used for onshore and offshore operations. RTP studied in this paper consists of a polyethylene liner, two layers of reinforced tape over wrapping the liner and an outer polyethylene coating. The inner liner pipe and outer coating pipe are high density polyethylene (HDPE). Xia et al. (2001) developed the stress analysis of the multi-layered filament-wound composite pipes under internal pressure based on the 3D anisotropy elasticity theory. Kruijer et al. (2005) developed a multi-layer ‘generalized plane strain’ model based on a plane strain characterization for RTP under hydrostatic pressure. Kobayashi et al. (2007) proposed an elastic-plastic analysis on the filament wound carbon fibre-reinforced composite pipes by applying partially plastic thick-walled cylinder theory.