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Material characterisation is fundamental to the effective design and analysis of elastomeric components; as a result many static test procedures and constitutive expressions have been developed over the years and subsequently used in Finite Element code. For many sealing applications quasi-static material properties have been used as an aid in design, typically for extreme and new structural configurations. Although it adequately captures the basic characteristics of a seal design it provides no information regarding the effects of dynamic excitation and how it affects the structural integrity of the seal. As a first order approximation interconversion relations were used to study dynamic effects on designs typically modeled with quasi-static material properties. Under dynamic loading it is possible for the contact force to fall below design tolerances.

The reliability of a valve stem seal (VSS) is directly related to its ability to deliver the correct rate of lubrication. Too little lubrication may result in valve stem wear; too much may result in ‘burnt’ valves and seats. The correct operational envelope will therefore depend upon an engineer's ability to predict how parameters such as seal geometry and material properties change over the life of the seal. This paper discusses the use of accumulative leakage measurements to study the life performance of a VSS as changes are made to ‘key’ design sealing features. A standard design VSS is used for ‘normal’ leakage bench marking. The results are to be used in the development of predictive leakage models that use both close scrutiny leakage testing and continued lubrication theory development.