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

Mechanical Engineering Department, The University of Texas at Austin, Austin, TX 78712, USA
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Entropy 2019, 21(7), 685; https://doi.org/10.3390/e21070685
Received: 14 May 2019 / Revised: 13 June 2019 / Accepted: 9 July 2019 / Published: 12 July 2019
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Abstract

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. View Full-Text
Keywords: fatigue; system failure; degradation analysis; entropy generation; stress strain; plastic strain; thermodynamics; health monitoring fatigue; system failure; degradation analysis; entropy generation; stress strain; plastic strain; thermodynamics; health monitoring
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Osara, J.A.; Bryant, M.D. Thermodynamics of Fatigue: Degradation-Entropy Generation Methodology for System and Process Characterization and Failure Analysis. Entropy 2019, 21, 685.

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