Fast evaluation of the fatigue lifetime of rubber-like materials based on a heat build-up protocol and micro-tomography measurements

The temperature of rubber-like materials increases under cyclic loadings, due to their dissipative behaviour and low thermal conductivity. This well-known phenomenon, called heat build-up, has attracted the attention of researchers for a long time. But, to our knowledge, no published studies have tried to link this temperature rise to fatigue behaviour, as already done for many metallic materials. Two main points are discussed in this paper. The first one is dedicated to heat build-up measurements: a specific experimental protocol was developed to capture the instantaneous heat build-up and, based on this protocol, a "heat build-up test" was defined in order to link the temperature rise to the principal maximum strain, which is a commonly used variable for fatigue criterion. A discussion on the correlation between these results and the fatigue behaviour is opened. This relation is illustrated for several industrial materials by a comparison between heat build-up measurements and fatigue life duration. The second point investigates the ability to couple X-ray tomography measurements presented elsewhere [1] to the former heat build-up results in order to predict the initiation lifetime. An approach based on a critical energy criterion was proposed and the comparison to a classic Wohler curve approach gave very good results.