Experimental and numerical study on the dry/wet burst failure of reinforced thermoplastic pipes

This paper investigates the burst failure of reinforced thermoplastic pipes (RTPs) via combined experimental and numerical research. Two completely different burst forms appeared during the experiments. The dry burst form occurs with matrix cracks, fiber breakage and crack of liner and coating, which is a common burst morphology. A new burst morphology, which is never reported in open literature, is observed in the experiments. This burst morphology, defined as wet burst form, presents a long dent in the coating and invisible composite damage. In order to simulate the burst failure of RTPs, a numerical model was proposed, in which element removal criteria and the nonlinear stiffness degradation model based on Hashin-Yeh failure criterion were employed to conduct progressive failure analysis on 3D composites. It was found that the wet burst form has lower burst pressure and causes larger damaged area, which is more dangerous in engineering. For the damage propagation, progressive failure occurs on middle composites and induces the final burst when the dry burst form occurs. As for the wet burst form, water flows into the middle of RTPs, which causes the delamination, matrix crack and bulge of coating. During the process, fibers play few roles in bearing loads.