Rotina computacional para análise de estanqueidade em motores de combustão interna

Abstract

Sealing between the cylinder head and the valve cover in internal combustion engines depends on the interaction between surface roughness and the behavior of the silicone sealant during assembly. In this work, a computational method was developed to evaluate metal–polymer sealing based on 3D surface roughness parameters and Persson’s theory for rough elastic contacts. The methodology integrated optical interferometry measurements, power spectral density, computation, and extraction of multiscale parameters, which were used to model the real contact area, the percolation threshold, and the fluid squeeze-out behavior of the silicone. The results showed that roughness and anisotropy play a determining role in valley connectivity and in the formation of preferential fluid-flow channels. The metal–polymer pairing significantly altered the spectral morphology of the interface, reducing the aluminum anisotropy and stabilizing the statistical distribution of heights. Combined surfaces exhibited an intermediate contact regime, in which the mean surface slope emerged as the primary controlling parameter of percolation, in agreement with multiscale theoretical predictions. The squeeze-out analysis indicated that highly anisotropic or excessively rough surfaces tend to retain larger volumes of sealant, whereas combined surfaces promote balanced drainage and more stable hydraulic closure. The developed method enables a direct correlation between topographic parameters and sealing performance, providing a robust tool for diagnosing failures and optimizing machined and molded surfaces in automotive applications.