Plane strain compression testing of polyoxymethylene at varying strain rates and elevated temperatures

Abstract

In this paper, the behaviour of three grades of polyoxymethylene (POM) in plane strain compression (PSC) has been studied at temperatures ranging from 120 to 160°C and strain rates ranging from 10⁻³ to 10⁻¹ s⁻¹ in order to provide material property data for modelling solid state orientation processes. All materials showed a similar stress–strain response characterised by an initial short linear viscoelastic region with a rounded yield point followed by an extended plastic regime with an approximately constant positive slope, indicative of linear strain hardening. It was demonstrated that the deformation behaviour of POM is strongly dependent on both temperature and strain rate. In addition, the plastic flow stress was found to be a linear function of the equivalent strain rate, suggesting an Eyring type thermally activated process. Finally, a simplified finite element material model was developed and shown to give good predictions of the PSC test data.