Honeywell-FRAM of Stratford, Ontario manufacture a wide variety of air filters typically used in automotive engine applications. These air filters incorporate a flexible molded polyurethane sealing bead. In a number of these sealing beads, tearing failures are occurring during service.

To develop an understanding of the causes of failure, a two dimensional finite element model of the sealing bead/housing cross-section was developed. A uniaxial tensile test and a confined compression test were performed to characterize the sealing bead material. Two elastomer material models, the modified Ogden model and the Foam model were fit to the data from the mechanical tests. For validation of the model, an experiment was also developed in which the seal was subjected to planar compression. At large compressions of the seal, good agreement was found between the experimental results and the finite element model employing the Foam material model. This model was used for all subsequent analysis.

A model of the existing sealing bead design showed regions of high strain which could cause tearing of the seal. This model also showed that the pressure distributions at the seal/housing interface are highly non-uniform. Alternative seal and housing designs were developed and modeled in which the maximum strains were greatly reduced. These # designs also require high closure forces but accommodate larger variations in the manufacturing tolerances.