Condition monitoring of O-ring seals with integrated strain gauges and finite element analysis assisted signal evaluation

In recent years, it has been shown that the degradation of an O-ring gasket during its lifetime can be correlated with the change in signal of a strain gauge, which has been embedded into the gasket. Yet, the deduction of an easy to understand, direct performance indicator for the gasket has not been addressed. In this work, we present a method that allows the interpretation of the measured signal change and results in the calculation of a simple performance indicator. This is achieved by using a Finite Element Analysis assisted signal evaluation approach. A model of an installed gasket is modified until the simulation predictions match the experimental data. The model is based on the assumption that the degradation of the gaskets performance is mainly driven by stress relaxation phenomena inside the elastomer material. By tuning stress relaxation parameters, the signal change of an embedded strain gauge can be adjusted. The remaining contact pressure of the gasket-to-compression plate-interface can be calculated from simulation and can be used as performance indicator for the gasket as the contact pressure mainly determines the sealing capability of the gasket.