Influence of temperature- and strain rate-dependent viscoplastic properties of polyoxymethylene on the thermo-mechanical response of a steel-polyoxymethylene spur gear pair

The nonlinear material properties of thermoplastics like polyoxymethylene (POM) can influence the thermomechanical response of polymer gears to applied running loads. In the presented study, the non-elastic strain rateand temperature-dependent mechanical characteristics of POM are examined, along with their influence on the mechanical response of the polymer gear at the tooth root and contact interface, and the resulting heat generation driving the commonly exhibited temperature rise during gear meshing/running. A detailed experimental study of these properties was conducted, employing standardized and partly customized tensile and bending tests. Using a suitable viscoplastic constitutive material model, calibrated based on the obtained experimental results, a numerical structural-contact analysis of the gear meshing process was performed, which could subsequently be used for a more detailed evaluation of the generated frictional heat and resulting temperature rise during gear running. While a significant influence of the viscoplastic material properties on the mechanical contact response and the flash temperature rise on the POM gear was identified, no major impact on the long term nominal temperature rise was recognized.