Numerical Analysis Of EHL And Its Application In Gear Transmission

Applying the combination of Newton iteration and gradient method, this paper analyzes theoretically the elastohydrodynamic lubrication of line contacts, and then researches practically that of involute spur gear. This paper uses the Newton-Raphson method as the main calculation tool. In view of the disadvantage of Newtonian method being strict to the choice of original value, the combination of selecting original value in advance with gradient method and citing the down-mountain factor in the iteration process accelerates the convergence velocity. The calculations show that this method achieves convergent solution through three to seven iterations. This method is presented firstly to solve the persistent ailment of the convergence being difficult, when Newton method is used to solve the EHL problems under the high speed or heavy load conditions. It is applicable for the cases of dimensionless rate parameter in the range from 10-12 to 10-10 , or of dimensionless load parameter in the range from 10-3 to 10-5, which may involve completely the practical applications of industrial gearing. After the numerical analysis, for gearing lubrication, the significant results.are achieved as follows:1. The value of second pressure-peak of gearing EHL pressure might reach about seven or eight times of maximum Hertzian stress. Therefore, in the prevail national or international calculation'- standards of gear strength, it is not scientific to design the fatigue strength in gear contacts based on Hertzian stress, and the results are sometimes not dependable.2. As the gear rotational speed increases the film thickness noticeably increases. However, the film thickness don't increase in single way with the increase of the module and number of gear-teeth.3. When the transmission ratio is equal to or less than 5, the film thickness goes up with its increasing. When the transmission ratio is more than 5. the film curve takes on concavity, but there is the phenomenon of neck contract in the exit.4. The different gear parameters effect on the EHL pressure in different degrees.