Study of the Stiffness of a Polymer Pinion Tooth in a Polymer-Metallic Spur Gear System

Over the years, the gear mesh stiffness is being studied extensively by researchers due to its ability to give a better understanding of a gear box dynamic behaviour. Many studies have used various methods to model the mesh stiffness of metallic spur gears such as square wave signal and finite element modelling. These models are based on combining the mesh stiffness pattern of each tooth involved in the gear meshing. This has proven to be effective in case of metallic gears. However, due to the viscoelastic behaviour of polymer, it is no longer possible to model the contact stiffness of a polymer pinion paired with a metal gear as a square-wave signal. In this study, the viscoelastic behaviour is taken into consideration. A Rheological model based on parallel Maxwell cells, called generalized Maxwell model, is used to model the contact behaviour of a polymer gear tooth. This model is ideal for steady-state harmonic excitation, which is the case of spur gears. The proposed approach is applied in the case of a pure nylon 6,6 gear paired with a metal pinion. It is then compared to the contact behaviour of a metallic gear tooth also paired with a metallic pinion.