Helical Gear Wear Prediction Under the Mixed Elastohydrodynamic Lubrication Regime

Abstract

To monitor the gradual wear process of gears, the wear behavior at different lifetime phases has to be fully understood in theory. The traditional Archard’s wear model was mainly developed for dry contact. However, for the most gear transmission systems, the gears normally work under the mixed EHL regime, and the two contact gear surfaces are separated by a thin film to avoid the asperity contact. Therefore, the traditional Archard’s wear model is inappropriate to estimate the wear depth of the lubricated contact. Moreover, the numerical simulation of helical gear wear was rarely studied because of the time-varying characteristics. To simulate the wear depth of helical gear in more realistic, the helical gear was regarded as a combination of a number of spur gears with a continuous different angle. By estimating the wear depth of each slice of the spur gear, the wear depth of the helical gear can be achieved. Besides, this paper employs a modified Archard’s wear model which is suitable for the contact in the mixed EHL regime. In this model, the asperity contact pressure was derived from the Hertzian contact theory, and both the friction effect, contact temperature, surface roughness, load sharing, and lubricant characteristics were considered for more realistic operating conditions. The sliding distance at each meshing position was determined by the single point observation method. The numerical results illustrate that the wear depth simulated from the mixed EHL regime is much lower than that under the dry contact condition, which is in good accordance with the lubrication theory. In addition, the wear depth increases with the operating load but decreases with the operating speed.