Continuous Compression Stress Relaxation of Rubber Materials - Testing and Simulation

Rubber is extensively used as gasket and seal materials. The force applied during clamp-up is stored in the deformed rubber and exerts back pressure against the flanges maintaining a tight seal. This sealing force will decrease with stress relaxation. lt will also change with temperature variation and resultant expansion or contraction of the seal, and change as the rubber swells or shrinks in the fluid being sealed.

Stress relaxation is regarded as being the most convenient method of evaluating the suitability of a given rubber material for sealing applications (Zhang and Birley 1992, Bunting et al., 1992). However, the conventional test, particularly the short-term test, can be misleading, since in actual application the rubber will function over a wide temperature range between metal flanges. The current continuous compression stress relaxation (CCSR) test aims to offer an improved method of evaluating rubber compounds.