Contact Mechanics of Rough Surfaces in Hermetic Sealing Studies

Abstract

It is indicated that the sealing capacity depends on the contact characteristics-the relative contact area and the gap density in the joint. To determine the contact characteristics, a discrete roughness model is used in the form of a set of spherical segments, the distribution of which in height is related to the bearing curve described by the regularized beta function. The contact of a single asperity is considered with taking into account the influence of the remaining contacting asperities. The equations for determining the relative contact area and gap density in the joint depending on the dimensionless force parameters for elastic and elastic-plastic contacts are provided.

Contact geometry during indentation of a sphere into an elastoplastic half-space

“…The operational performance of the joints of machine parts, including tightness, are determined of the relative contact area and the density of the gaps at the junction of rough surfaces [1,2]. For determining contact characteristics at the junction of rough surfaces, various roughness models are widely used, in which microasperities (hereinafter, asperities) are represented as spherical segments with the same radius.…”

“…Moreover, the asperities height distribution corresponds to the normal law [3] or the surface bearing curve [1,4]. It should be noted that in [2] the equation of the entire profile bearing curve is used, and not only its initial part as in [1,2,4]. For elastic contact of asperities, Hertz theory is used to determine contact characteristics.…”

“…The volume of gaps in the joint is determined by the total volume of gaps per one asperity, which is determined by the geometry of the contactthe indentation depth of the asperity h , the contact depth c h and the profile of the deformable surface. If the problem of determining the density of gaps is solved for an elastic contact of asperities, including under the mutual influence of asperities [2,9,10], then for an elastic-plastic contact this solution is associated with "sink-in / pile-up" effects ( Fig. 1).…”

Relative contact area in metal-polymer joints

“…An important characteristic in determining the performance of joints of machine parts is the relative contact area. As follows from [1][2][3], as well as from the recent publications of the authors [4][5][6][7], for determining the relative contact area and especially with the use of lowmodulus materials, the mutual influence of microasperities should be taken into account. In these studies, using the discrete roughness model, analytical equations are given for determining the relative contact area as a function of the dimensionless force elastic geometric parameter y f .…”

“…It follows from [4][5][6][7] that without taking into account the mutual influence of the asperities, with using a discrete roughness model, the case is possible when 1 = η . This contradicts the data of [11][12][13][14][15] devoted to the study of almost full contact between rough surfaces.…”