Simulation of the crack growth in the weld of the polyolefin pipes

The aim of this work was to study the effect of the material properties change due to the butt welding on the stress intensity factor in polyolefin pipe. The gradient change of the Young’s modulus was assumed. The crack was located in the middle of the affected zone. The stress intensity factors estimated in both graded region and basic material (homogenous case) were compared. Strong influence of the graded region on the value of the stress intensity factor was observed. Therefore, for realistic estimation of the welded pipe lifetime the change of the material properties inside the polymer weld should be taken into account