Quantitative assessment of deformation-induced damage in polyethylene pressure pipe

This paper presents results from a study that quantifies the influence of excessive deformation on the damage development in polyethylene (PE) pressure pipe. The experimental investigation is through the application of a novel two-stage approach to the D-split test of notched pipe ring (NPR) specimens. The first test is to introduce damage by subjecting the specimens to different levels of tensile strain at crosshead speeds of 0.01, 1, 10 or 100 mm/min. The second test is to apply monotonic tensile loading at a crosshead speed of 0.01 mm/min to characterize the mechanical properties for specimens that have had damage generated in the first test. Experimental results suggest that elastic modulus and yield stress decrease and yield strain increases with increase of the strain introduced in the first test. Variation of experimentally measured elastic modulus is used to establish influence of crosshead speed on the damage evolution in the PE pressure pipe.