Tensile strength and work of fracture of oriented polyethylene fibre

Abstract

In the present investigation the influence of strain rate and temperature on modulus, strength and work of fracture of high-performance polyethylene (HPPE) fibre is studied. At low temperature and/or high strain rates the fibre shows brittle failure, displaying a pronounced strain rate and temperature dependence of the tensile strength. At high temperatures and/or low strain rates a transition from a brittle to a ductile failure mode could be observed. This brittle-to-ductile transition is analysed in terms of competitive failure modes, which leads to a simple model that can be used to predict the strain-rate dependence of the transition temperature. In the brittle failure mode it is observed that an increase in strain rate and/or decrease in temperature leads to a reduction in work of fracture. This reduction could successfully be predicted by combining a previously published mathematical model for the deformation of HPPE fibres with the observed strain-rate dependence of the tensile strength. From the numerical simulations it can be deduced that a constant minimum level for the fracture energy will be reached at high strain rates or low temperatures.