Stress-Strain Behaviour of a Low Density Polyethylene under Complex Strain

Abstract

A description of a simple non-linear form of viscoelasticity in terms of logarithmic strain is given together with a correction factor. Apparatus is described for determining relaxation data in simple tension and results are given for a low density polyethylene. These results are then used in conjunction with the theory to predict behaviour in simple tension at various strain rates, at various constant strain ratios in loading only, stress relaxation under complex stress and in tests with varying strain ratios. An apparatus is described to obtain such data and the results are compared with the theoretical predictions.