Self-contact in rubber/foam components: rubber gasket

Components that deform and change their shape substantially can fold and have different parts of the surface come into contact with each other. In such cases it can be difficult to predict at the outset of the analysis where such contact may occur and, therefore, it can be difficult to define two independent surfaces to make up a contact pair.

This model is used to analyze an oil pan gasket, which enhances the sealing of the oil pan against the engine block. A primary objective of gasket designers is to reach or exceed a threshold value of contact pressure at the gasket bead/cover/engine block interfaces. Experience shows that, above such a threshold, oil will not leak. Another item of interest is the load-deflection curve obtained when compressing the gasket cross-section since it is indicative of the bolt load required to attain a certain gap between the oil pan and the engine block. Finally, the analysis provides details to ensure that stresses and strains are within acceptable bounds.

The rubber gasket is embedded in a plastic backbone. It has two planes of symmetry and a bead that, when compressed, provides the sealing effect (Figure 1). A flat rigid surface, parallel to one of the symmetry planes, pushes the gasket into the backbone. The geometry of the gasket is such that it folds in two different locations. In this model the entire free surface of the gasket and of the backbone is declared as a single surface allowed to contact itself. This modeling technique, although very simple, is more expensive because of the extensive contact searches required, as well as a larger wavefront of the equation system when using Abaqus/Standard.

The analysis is performed using both Abaqus/Standard and Abaqus/Explicit.