A study of crack propagation in high-density polyethylene

Abstract

In recent published work a method was proposed to calculate fracture toughness during the crack-propagation phase of the loading of notched specimens. In this paper, it is proposed that the fracture toughness, J can have a value that does not exceed the product of the ultimate work to failure of the material, Wf, times a charactersitic remaining ligament length bm. It is proposed that crack propagation is unstable at ligament lengths less than bm and does not, therefore, demand further strain–energy input. The fracture toughness J at any particular remaining ligament length b can be calculated from a term that is related to the area under the curve of the net section stress vs. the ratio of plastic load point displacement of remaining ligament length. Experimental data on the loading of double-edge-notched specimens of high-density polyethylene that were extended to failure were used to test the proposed theory. The experimental results were encouraging, although not conclusive, in supporting the proposed method of relating the crack toughness to the known material properties of the subject material.