A temperature-only system degradation analysis based on thermal entropy and the degradation-entropy generation methodology

System degradation and material transformation are detected, analyzed and predicted using only temperature measurements. The method combines fundamental thermal energy and entropy balances with the degradation-entropy generation theorem to characterize multi-physics system-process interactions. Various experimental measurements verify the analysis and results. A universally consistent system- and process-independent model is derived, that relates heat transfer and heat storage to the system's phenomenological transformation and renders new material and process parameters for system analysis. The recently proposed maximum work-based DEG methodology is reviewed and compared to the temperature-only approach of this article. Applications to general fatigue, grease aging and lithium-ion battery degradation cycling are presented. System- and process-characteristic degradation coefficients are obtained from measured data. Similar to the maximum work models, a near 100% correlation between the temperature-only model and the nonlinear data from uncontrolled experimental measurements is observed. Model-predicted trends accord with established system behavior. The approach can be easily adapted to all systems undergoing active thermal transformations for performance characterization and optimization.