Thermodynamics of Fatigue: Degradation-Entropy Generation Methodology for System and Process Characterization and Failure Analysis

Jude A. Osara, Michael D. Bryant

Research output: Contribution to journalSpecial issueAcademicpeer-review

12 Citations (Scopus)
20 Downloads (Pure)


Formulated is a new instantaneous fatigue model and predictor based on ab initio irreversible thermodynamics. The method combines the first and second laws of thermodynamics with the Helmholtz free energy, then applies the result to the degradation-entropy generation theorem to relate a desired fatigue measure—stress, strain, cycles or time to failure—to the loads, materials and environmental conditions (including temperature and heat) via the irreversible entropies generated by the dissipative processes that degrade the fatigued material. The formulations are then verified with fatigue data from the literature, for a steel shaft under bending and torsion. A near 100% agreement between the fatigue model and measurements is achieved. The model also introduces new material and design parameters to characterize fatigue.
Original languageEnglish
Article number685
Issue number7
Publication statusPublished - Jul 2019
Externally publishedYes


  • fatigue
  • system failure
  • degradation analysis
  • entropy generation
  • stress strain
  • plastic strain
  • thermodynamics
  • health monitoring

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