Investigation on the Mechanical Behavior of Polyethylene Pipes Reinforced by Winding Steel Wires under Radial Compression

A steel-wire reinforced thermoplastic pipe (PSP) consists of high-density polyethylene (HDPE) as a matrix and helically wound steel wires as reinforcements. Due to its unique structure and material combination, the PSP possesses relatively great strength and excellent corrosion resistance as a cost-effective composite pipe. In this work, it is the first time, to the best of our knowledge, to study and predict the mechanical behavior of the PSP under radial compression. Experimental investigations were conducted to obtain the force-displacement curves of the PSP with different structural parameters under radial compression, as well as the strain along different directions. A theoretical model and a finite-element model (FEM) of the PSP under radial compression were proposed to predict the mechanical responses of the pipe. The theoretical model was based on the laminated plate theory, and the FEM considered the nonlinear mechanical properties of the steel wire and the HDPE. After the comparison of the experimental results, both the theoretical model and FEM were validated to predict the ring stiffness of the pipe. In terms of accuracy of the prediction, the theoretical model could deliver satisfactory results with a maximum error of 3.07% within a small radial deformation of 3%, and the FEM could provide excellent prediction with a maximum error of 11.18% throughout the whole compression process with a radial deformation of up to 60%. Further, based on the FEM, the mechanical behavior of the PSP was analyzed, and the influence of different structural parameters was studied on the resistance of the PSP to the radial deformation. FEM results revealed that the existence of steel wires is important for radial deformation resistance, but its number has limited influence, while wall thickness and pipe diameter significantly impact mechanical performance, as increasing wall thickness enhances radial deformation resistance but a larger diameter reduces it. This study might provide the theoretical basis and practical guidance for composite pipe design.