Fracture Behavior of Cracked Ring Specimen at Different Crack Positions

The previous research review of piping systems revealed that the plastic pipe companies suffered from many problems in natural gas pipeline systems. One of the most significant problems that appeared in the piping systems are external cracks due to manufacturing processes, welding technique, and installation processes. The principal goal of the present experimental study is to predict the crack growth behavior and energy release rate of cracked ring specimens made from high-density polyethylene (HDPE) under different crack position angles and various crosshead speeds. The effect of loading rate on the external radial crack at different crack position angles plays an important role in the prediction of fracture behavior of plastic pipe materials. For this reason, it is necessary to conduct a study for the fracture analysis of pipe ring specimens under tension loading with double external cracks at constant radial crack length to width ratio equal a/W=0.5. A precracking machine is designed especially in the present experimental study to simulate the actual radial cracks at outer surface of pipe ring specimens. The effects of crosshead speed and crack position angle revealed a significant effect on the energy release rate and maximum applied load under tensile load.