Effect of friction on the contact stress of a coated polymer gear

Abstract

Polymer gears are used extensively in various applications. However, durability issues have been emerging because of friction at gear tooth contact areas. To extend the lifetime of polymer gears, a low-frictional coating has been considered as a possible strategy. In this study, a finite element simulation method was performed to investigate the contact stress between a pair of coated polymer gears. The simulation included various friction coefficients (COFs) for studying the effects of friction during the operation. Numerical results revealed that the friction causes the contact stress to shift over the roll angle, which is attributed to the direction of the sliding friction based on a free-body diagram. We also investigated the effects of coating and found that a thin coating has little effect on the bulk deformation behavior of the gear. Moreover, the stress distribution in the coating at the pitch point was investigated as the COF increased. Under zero friction, three notable stress regions were observed: 1) the center of the surface, 2) the end of the contact, and 3) the overall contact area. As COF was increased in the micro-slip region of the contact interface, both tensile and compressive stresses in the coating increased. This study provides significant aid to engineers for understanding the stress response of the coating applied to polymer gears to achieve an optimal design.

Formation of discrete periodic nanolayered coatings through tailoring of nanointerfaces—Toward zero macroscale wear

“…7, H and I) (58). According to previous studies (59,60), an additional bending effect at the edges of the contact zone coating can be caused by the groove geometry and the pile-ups. This bending can, in turn, result in generation of compressive and tensile stresses in addition to the stresses caused by the contact.…”

Experimental Investigation of the Wear Behaviour of Coated Polymer Gears

“…The experimental results indicated that the PTFE-coating provided the greatest reduction of friction and wear for the analysed polymer gears. Furthermore, Bae et al [ 31 ] proposed an FEM-model to investigate the contact stress response of a coated polymer gear with the frictional effect during gear operation. Their numerical results have shown that a coating of 2 μm thickness had a negligible effect on the contact stress during the mesh cycle, because the thickness was insufficient to affect the bulk deformation behaviour of the polymer gears.…”

Nonlinear characteristics of a multi-degree-of-freedom wind turbine’s gear transmission system involving friction

“…Chen et al [21] studied the calculation method of friction coefficient and meshing efficiency of plastic wire gear pair under dry friction condition, the dynamic characteristics of the system under dry friction condition are obtained. Bae et al [22] adopts finite element simulation method to the contact stress between coated polymer gears considering different friction coefficients. Keller et al [23] established a thermal elastohydrodynamic model for the single tooth gear.…”