Fracture surface features of polyethylene pipe samples

Slow crack growth behavior of medium‐density polyethylene pipe samples has been investigated by applying standard and nonstandard fracture mechanics test methods. Slow crack growth rate varied by several orders of magnitude among the PE2306 materials from different manufacturers. Slow crack generated surfaces exhibit fibrous textures of varying degrees of coarseness when examined under the scanning electron microscope. When the measured fiber heights, δ/2, of these samples were plotted against the applied stress intensity factor, K I , they showed a simple power law relationship (of exponent 2). Assuming that the pulled‐out fibers transmit almost uniform tensile stresses across the crazed zone at the crack front, the Dugdale‐Barenblatt model was introduced to predict the fiber height. Although the model needs further modification, it provides a general power law relationship between the fiber height and the applied stress intensity factor.