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Abstract
An FFT-based approach for fast estimation of pressure distribution in point EHL contacts of rough surfaces is developed in order to reduce computing time, as full numerical deterministic models may require several days to analyze one case on a personal computer. As is known, any 3-dimensional surface roughness can be decomposed into a series of sinusoidal waves with different wavelengths and orientation angles. Based on an assumption that each elemental wave causes basically a sinusoidal pressure fluctuation with the same frequency and orientation angle, an EHL system model and an input/output relationship are derived. Five constants in the relationship are determined through fitting numerical results from 50 selected cases. By means of Fast Fourier Transform (FFT), the system model could give an estimated pressure distribution for full film EHL or mixed lubrication within a few seconds. Sample cases show however, that, the estimated pressure is in agreement with full numerical solutions only for some selected rough surfaces. The estimation error becomes quite significant for 3-D isotropic roughness. Generally the agreement may be fairly good for the pressure profiles in the direction perpendicular to the roughness ridges, but it is poor for those in the direction parallel to the ridges. It is believed that errors associated with the simplified model and curve fitting can possibly be reduced, but those related to the inaccurate assumption on roughness/pressure correspondence are difficult to remove, which may leave a deficiency in the proposed approach. The authors believe that the results presented in this paper may provide useful information for other researchers who are interested in developing fast approaches for EHL and mixed lubrication.
Presented at the 54th Annuel Meeting In Las Vegas, Nevada May 23–27, 1999
Notes
Presented at the 54th Annuel Meeting In Las Vegas, Nevada May 23–27, 1999