Abstract
In this paper, the elasto-plastic and viscoelastic properties of two grades of polyethylene are investigated by cylindrical macro-indentation. Indentation tests, including relaxation tests, are performed with a cylindrical indenter having a flat-tip diameter of 1 mm. The bulk properties, such as the indentation modulus and the yield stress, are extracted from the indentation stress-displacement curves. The indentation relaxation data of polyethylene are analyzed using the steady-state creep model and the generalized Maxwell model. Based on experimental data and the Prony series model, equilibrium stress, relaxation ratio and relaxation time are determined, while the creep exponent and the characteristic relaxation time are estimated using the steady-state creep model. Keywords:cylindrical macro-indentation, relaxation tests, steady-state creep model