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Abstract
The aim of this article is to provide some relevant statistical parameters for mechanical seal faces and to present some methods of modelling them in order to study mixed lubrication.
Three mechanical seals with faces of three different material combinations were analyzed at three operating times (unused, run-in, and worn). Surface roughness and waviness were analyzed. Generally speaking, the amplitude of the waves tends to increase with time, whereas roughness height shows the opposite trend, except in the case of the hard faces combination. The seal surfaces are extremely skewed, this phenomenon being enhanced by wear. The surfaces are nearly isotropic with a slightly higher correlation length in the sliding direction.
Two models with two different autocorrelation functions (ACFs) were used to simulate surfaces. These models, based on the Patir approach (Patir (1)), used the Johnson translation curves to impose non-Gaussian height distribution. Even if the models are able to reproduce experimental tendencies, there are some difficulties with the modeling of large structures, leading to the overestimation of summit density and underestimation of the radius of the asperities’ curvature. Generally speaking the exponential ACF gives better results than the bilinear ACF.
ACKNOWLEDGEMENT
Particular thanks are due to the Sealing Technology Department of the CETIM for supporting this research project.
Review led by Gregory Kostrzewsky