Effect of strain rate on bending and transmission characteristics of injection molded polyamide 66 spur gears

摘要

Polymer material exhibits time-dependent mechanical behavior due to its viscoelastic characteristics. Thus, unlike steel gears, polymer gears exhibit complex behavior when transmitting loads at various rotational speeds. In general, gear tooth surfaces exhibit complex stress due to their nonconformal geometry. Hence, the nonlinear material and nonlinear geometric aspects of polymer gear mesh prompted an investigation of the bending and transmission characteristics of injection molded polyamide 66 gears at various strain rate conditions. The injection molded tensile specimens made from the gear material were subjected to various rates of loading. The stress-strain performance at various rates of loading was evaluated and used to model linear and nonlinear gear materials for the numerical analysis. The numerical investigation was carried out on the steel-polyamide gear pair with the commercial finite element analysis tool ABAQUS (R) to predict the bending stress and static transmission error. The predicted static transmission error of the gear pair was compared with the experimental results obtained using an in-house developed gear test rig. The bending stress with the linear material models was higher than that of the nonlinear material models. An increase in bending stress with the strain rate was observed in the case of the nonlinear material models. The static transmission error predicted with the nonlinear material model at a higher strain rate was lower for both the single tooth contact and the double teeth contacts.