An Entropy-Based Damage Characterization

Abstract

This paper presents a scientific basis for the description of the causes of damage within an irreversible thermodynamic framework and the effects of damage as observable variables that signify degradation of structural integrity. The approach relies on the fundamentals of irreversible thermodynamics and specifically the notion of entropy generation as a measure of degradation and damage. We first review the state-of-the-art advances in entropic treatment of damage followed by a discussion on generalization of the entropic concept to damage characterization that may offers a better definition of damage metric commonly used for structural integrity assessment. In general, this approach provides the opportunity to described reliability and risk of structures in terms of fundamental science concepts. Over the years, many studies have focused on materials damage assessment by determining physics-based cause and affect relationships, the goal of this paper is to put this work in perspective and encourage future work of materials damage based on the entropy concept.

A Thermodynamic Entropy Approach to Reliability Assessment with Applications to Corrosion Fatigue

“…An interesting aspect of the principle of entropy increase is the special light it sheds on the concept of time direction and evolution of events. In accordance with the principle of entropy increase, manufactured organized components return to their natural conditions through degradation, which reduces the integrity of material properties to the point where the components are no longer functional [2].…”

“…The benefit of employing entropy generation to characterize materials damage is that entropy generation can provide a unified measure of damage, allowing for incorporation of multiple competing and common-cause degradation mechanisms that can be explicitly expressed in terms of physically measurable quantities. Furthermore, entropy as a thermodynamic state function is independent of the path of the failure (which commonly depends on factors such as environmental condition, geometry, load, and frequency of load) from the initial state to the final failed state of the material, considering a known endurance limit [2,21].…”

“…A comprehensive review of applications of entropy concepts in various research areas is given by Martyushev and Seleznev and Amiri and Modarres [2,12]. Entropy can be used to quantify the behavior of irreversible degradation, including plasticity and dislocations [13,14], erosion-corrosion [15], wear and fracture [16][17][18][19][20], fatigue [21][22][23][24][25][26], fretting corrosion [27], thermal degradation [28], and associated failure of tribological components [29,30].…”

“…In thermodynamics, dissipation of energy (in processes such as chemical reactions, release of heat, diffusion of materials, and plastic deformation) is the basic measure of irreversibility and the main feature of degradation processes in material [2,8]. In turn, dissipation of energy can be quantified by the entropy generation within the context of irreversible thermodynamics [9][10][11].…”

Evaluation of fatigue crack growth rate for iron-carbon metals based on degradation-entropy generation theorem

“…The driving motivation regarding the creation of the Degradation-Entropy Generation (DEG) theorem is often described as the fundamental understanding that entropy monotonically increases and free energy monotonically decreases for every natural processes understanding that an entropy-generating irreversible process accompanies all aging phenomena. Following the strategy of entropy increase, manufactured organized components turns into their natural conditions through degradation which reduces the integrity of material properties and being finally non-functional [11]. However, within the framework of fracture mechanics, the entropy generated from crack propagation is an aspect which has not been thoroughly investigated.…”