Vibration and cavitation in high-speed gears caused by faults

Abstract

In high-speed gear transmission, cavitation occurs easily due to vibration. When gear has pitting or crack fault, the cavitation will be more violent due to stronger vibration, causing potential safety hazards. However, researches on gear cavitation mechanism considering pitting and crack are limited. For studying the cavitation mechanism of faulty gear, a model combined computational fluid dynamics and faulty gear dynamics has been proposed, being regarded as the innovation of this paper. The dynamic characteristics of the faulty gear is obtained by solving the gear finite element model, and the results will be applied to the analysis of lubricating oil flow characteristics as boundary conditions. For proving the validity of the proposed model, the simulation results are compared with the available experimental results. Moreover, the novelty of this paper is to consider the influence of gear failures on cavitation, factors such as rotational speed, pitting depth and crack depth are discussed, tooth profile changes are also considered. The results indicate that gear faults have greater impact on cavitation at high speeds. At 10,000 rpm, with the deepening of pitting, the cavitation intensity will increase firstly and then decrease. When the pitting depth increases from 0.2 mm to 0.3 mm, the root mean square value of average vapour volume fraction decreases from 0.0752 to 0.0724. For cracked gears, the crack depth will affect the cavitation enhancement rate. The increase rate of cavitation decreases from 17.4 to 1.1% when crack depth increases from 1 to 4.5 mm. This study provides an effective tool for gear cavitation suppression and high reliability.