Contact Elasticity of Seal Elastomers

Abstract

The calculation of Young’s modulus of an elastomer is based on the optical measurement of the contact between a transparent spherical indenter and the elastomer. The technique is based on Hertzian contact analysis and agrees with the work done by others on the depth of penetration of indenters. A critical comparison of this method is made with conventional hardness tests. Experimental work establishes the fact that determinations of Young’s modulus based on indentations in thin samples are permissible only if the strains in the elastomer are kept below a calculable limit. The dependence of elastomer modulus on prior strain is described and fluid-elastomer interactions are examined in detail.