Characterisation of Fatigue Crack Growth in Silicone for Deap Technology

In this paper, the fatigue crack growth characteristics of Elastosil R RT 625 are determined by performing fatigue crack experiments based on ISO 27727. Elastosil R RT 625 is a silicone rubber used by Danfoss PolyPower A/S as the dielectric material in their DEAP elements. Cracks were characterised by a large amount of crack tip roughening, and a crack pattern that oscillated around the mean crack propagation direction.

The amount of deviation from the expected crack path was proportional to the strain-level in the test. Despite the rough oscillating crack appearance, a linear relationship between the crack length and the amount of cycles was obtained. When plotting the crack growth per cycle against the applied load, the existence of a power law domain which can be described by Paris’ Law was observed.

The silicone rubber had a significantly lower b exponent than a large range of other rubbers.