On the relationship between mechanical energy rate and heat dissipated rate during fatigue for a C45 steel depending on stress ratio

This work deals with the analysis in the frequency domain of the temperature signal and mechanical energy rate of C45 steel under two different fatigue stepwise loading series at stress ratios of 0.1 and −1. It was first investigated the energy distribution among the harmonic components of the signals to understand possible variations caused by a different stress ratio. In addition, the second amplitude harmonic (SAH) of heat dissipated and mechanical energy rates have been considered in the analysis, and their relationship was investigated. It has been shown as it depends only on the material, and hence, it is valid whatever the kind of the test is without any assumption on the energy supplied to the material or material hysteresis loop stabilization. The adopted approach allows the analysis of intrinsic dissipations by means of rapid, full-field, and contactless techniques without any specific requirement on loading condition or temperature signal stabilization.