ABSTRACT

ABSTRACT: Many industries work extensively with NBR and HNBR elastomers because they work well at high temperatures and in hostile chemical environments such as organic solvents. Both elastomers are widely used in applications such as dynamic sealing, where they can be exposed to high strain rates, high frequencies, high temperatures and in contact with oil based fluids. Therefore, characterising their fatigue properties under these extreme conditions is essential when trying to predict failure in service. Using a fracture mechanics based approach enables a prediction of the lifetime of a component. This requires the material’s tear resistance to be measured first. This behaviour is expressed as the relationship between the strain energy release rate (sometimes known as the tearing energy) and the fatigue crack growth rate under different conditions. The experimental process required to measure cyclic pure shear fatigue crack growth test of two HNBR samples before and after ageing at 100°C for 168 hours is described and the results are discussed.