Measures of Entropy to Characterize Fatigue Damage in Metallic Materials.
Huisung Yun,Mohammad Modarres +1 more
TLDR
Three entropic theorems—thermodynamics, information, and statistical mechanics—support approaches used to estimate theEntropic-based fatigue damage, and an empirically-based pseudo-Boltzmann constant equivalent to the Boltzmann Constant is demonstrated.Abstract:
This paper presents the entropic damage indicators for metallic material fatigue processes obtained from three associated energy dissipation sources. Since its inception, reliability engineering has employed statistical and probabilistic models to assess the reliability and integrity of components and systems. To supplement the traditional techniques, an empirically-based approach, called physics of failure (PoF), has recently become popular. The prerequisite for a PoF analysis is an understanding of the mechanics of the failure process. Entropy, the measure of disorder and uncertainty, introduced from the second law of thermodynamics, has emerged as a fundamental and promising metric to characterize all mechanistic degradation phenomena and their interactions. Entropy has already been used as a fundamental and scale-independent metric to predict damage and failure. In this paper, three entropic-based metrics are examined and demonstrated for application to fatigue damage. We collected experimental data on energy dissipations associated with fatigue damage, in the forms of mechanical, thermal, and acoustic emission (AE) energies, and estimated and correlated the corresponding entropy generations with the observed fatigue damages in metallic materials. Three entropic theorems—thermodynamics, information, and statistical mechanics—support approaches used to estimate the entropic-based fatigue damage. Classical thermodynamic entropy provided a reasonably constant level of entropic endurance to fatigue failure. Jeffreys divergence in statistical mechanics and AE information entropy also correlated well with fatigue damage. Finally, an extension of the relationship between thermodynamic entropy and Jeffreys divergence from molecular-scale to macro-scale applications in fatigue failure resulted in an empirically-based pseudo-Boltzmann constant equivalent to the Boltzmann constant.read more
Citations
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A new method for detecting fatigue crack initiation in aluminum alloy using acoustic emission waveform information entropy
TL;DR: In this paper, the authors used the information entropy of acoustic emission (AE) signals to identify precursors to fatigue crack initiation in AA7075-T6 airframes.
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Low Cycle Fatigue Life Prediction Using Unified Mechanics Theory in Ti-6Al-4V Alloys.
TL;DR: The unified mechanics theory can be used to predict fatigue life of Ti-6Al-4V alloys by using simple predictive models that are based on fundamental equation of the material, which is based on thermodynamics associated with degradation of materials.
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Noise Reduction in Spur Gear Systems.
Aurelio Liguori,Enrico Armentani,Alcide Bertocco,Andrea Formato,Arcangelo Pellegrino,Francesco Villecco +5 more
TL;DR: A static analysis was carried out in order to describe how stresses resulting from meshing gears affect theoustic emissions, and it was shown that changing the material from steel to ductile iron improved the gear noise, while increasing the rotational speed or the friction increased the acoustic emissions.
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A Review of Damage, Void Evolution, and Fatigue Life Prediction Models
Hsiao Wei Lee,Cemal Basaran +1 more
TL;DR: Degradation, damage evolution, and fatigue models in the literature for various engineering materials, mostly metals and composites, are reviewed in this article, where the development and applications of unified mechanics theory is reviewed.
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Experimental determination of entropy and exergy in low cycle fatigue
TL;DR: In this paper, the existence of a threshold of entropy and exergy in low cycle fatigue for a flat Al-2024 specimen measuring the heat generated during a fatigue test was observed.
References
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Journal ArticleDOI
Information Theory and Statistical Mechanics. II
TL;DR: In this article, the authors consider statistical mechanics as a form of statistical inference rather than as a physical theory, and show that the usual computational rules, starting with the determination of the partition function, are an immediate consequence of the maximum-entropy principle.
Book ChapterDOI
Cumulative damage in fatigue
TL;DR: The aircraft designer today is faced with the necessity of estimating not only the strength of a structure, but also its life — a task with which he was not confronted before.
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TL;DR: Theoretical Bases for Calculating the ARE Examples of the Calculations of Efficacy and ARE Analysis of Count Data.
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Entropy production fluctuation theorem and the nonequilibrium work relation for free energy differences
TL;DR: A generalized version of the fluctuation theorem is derived for stochastic, microscopically reversible dynamics and this generalized theorem provides a succinct proof of the nonequilibrium work relation.
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