Modeling Degradation Using Thermodynamic Entropy

Michael D. Bryant
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Full Paper
phmc_14_076.pdf926.16 KBSeptember 23, 2014 - 3:06pm

Manufacture transforms raw materials into finished components. Aging and degradation irreversibly transforms the material structures, which compromises components. Degradation is driven by irreversible dissipative processes that dissipate energy and disorganize material structures. The second and third laws of thermodynamics assert that all these processes must generate entropy. Since aging and degradation involve irreversible dissipative processes, the entropy generated by these irreversible processes is a fundamental and natural quantity to describe aging and degradation.

This recognition led to a Thermodynamic Degradation Paradigm, with formulation and proof of a Degradation Entropy Generation Theorem, wherein the rate of degradation was related to the irreversible entropies produced by the underlying dissipative physical processes. This paradigm permits a structured approach to modeling degradation of any kind. If properly applied, the Degradation Entropy Generation Theorem leads to a differential equation in the degradation variable which depends on the environmental and operational variables of the system. This approach has led to models for wear, fatigue, and battery degradation, which are consistent with all prior models, and which has accurately predicted degradation and failure.

This presentation will review the Thermodynamic Degradation Paradigm, review the recently published Degradation Entropy Generation Theorem, and apply the paradigm and theorem to form predictive models of degradation including wear, fatigue, and battery degradation, among others.

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Submission Keywords: 
failure analysis
Submission Topic Areas: 
Physics of failure
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