Control of friction by imposing vibration between sliding surfaces and its influence on the efficiency of gears

Udaykant Jadav, Priyang

Abstract

The worm and wheel type gear arrangement is the usual choice for heavy duty applications requiring large operating torques. However, it is dominated by the sliding action of gear teeth which causes high frictional losses that significantly impact efficiency. The use of vibration is investigated as a method of reducing the frictional losses in worm gearing.
Pre-existing mathematical models that describe the mechanism of friction reduction due to in-plane vibration are further developed and executed analytically. Comparable results of friction reduction are obtained when the models are implemented into 3D finite element simulations of a sliding mass driven across a vibrating surface. The 3D numerical simulations are extended to evaluate the effect of vibration on friction in a worm gearset operating under load. Axial sinusoidal vibration applied to the worm enables an 80% reduction of input torque to generate the same output torque. This constitutes a five-fold increase in gearset mechanical advantage but a drop in overall system efficiency due to electrical power consumed to generate the vibration. The extent of input torque reduction is governed by the ratio of vibration velocity amplitude to the contact sliding velocity of the gearset.
Vibration experiments are conducted using a custom disc-on-disc friction test rig representing a contact similar to that of worm gearing. Test variables include lubricant type, vibration mode, vibration waveform, vibration frequency and sliding speed. In extension to previous studies that have investigated vibration-friction interactions only under dry pure-sliding conditions, disc-on-disc vibration experiments demonstrate presence of the friction reduction effect also under lubricated sliding-rolling conditions. Sinusoidal wave vibration produces greater friction reduction than triangular, and contrary to previous studies, transverse vibration experiments produce greater friction reduction than longitudinal.
As friction is intrinsic to the mechanics of everyday life, this research has relevance to any application seeking to reduce this dissipative contact force. In particular, this research shows that friction in lubricated sliding-rolling contact can be reduced by imposing vibration. In worm gearing this improves the mechanical advantage but impacts the overall system efficiency. This is not considered a problem if vibration can be temporarily activated for a momentary boost in mechanical advantage when it is most needed.

• Thesis Type: Thesis
• Deposit Date: Apr 29, 2022
• Publicly Available Date: Oct 4, 2024
• Public URL: https://uwe-repository.worktribe.com/output/9434292
• Award Date: Oct 3, 2022