Studies on Fracture Mechanics Design of Electro-Fusion Joint Made of High Density Polyethylene

摘要

Cylindrical non-fused sharp notch is produced between the electro-fusion Polyethylene joint and the outerrncircumferential edge of the Polyethylene pipe in their fusing process. Fracture toughness of Polyethylene andrnthe value of the stress intensity factor at the tip of the sharp notch are required for the joint to be designedrnsafely based on linear fracture mechanics. In this study, three point bending tests are performed for a singlernedge notch specimen over the temperature range from -196 to -120. Fracture toughness is evaluated using thernload at which a crack propagation initiates from the notch tip of the specimen. Fracture toughness takes arnminimum value of 3.47MPa·m1/2 at -120. Using finite element method with three-dimensional singularrnelements, the monographs on both the Mode I and the Mode II stress intensity factors for variousrncombinations of the geometry of the joint are established. As an example, the safety of the electro-fusionrnjoint EF100 is demonstrated from the view point of linear fracture mechanics.