10. Development of a Generalized Entropic Framework for Damage Assessment

Data-driven stochastic and probabilistic methods that underlie reliability prediction and structural integrity assessment remain unchanged for decades. This paper develops an alternative approach to reliability assessment in terms of fundamental concepts of science within the irreversible thermodynamic framework. The common definition of damage, which is widely used to measure the reduction of reliability over time, is based on observable markers of damage at different geometric scales. Observable markers are typically based on evidences of any change in the physical or spatial properties or the materials, and exclude unobservable and highly localized damages. Thermodynamically, all forms of damage share a common characteristic: “energy dissipation”. Energy dissipation is a fundamental measure of irreversibility that within the context of non-equilibrium thermodynamics is quantified by “entropy generation”. The definition of damage in the context of thermodynamics allows for incorporation of all underlying dissipative processes including unobservable markers of damage. Using a theorem relating entropy generation to energy dissipation associated with damage producing failure mechanisms, this paper presents an approach that formally describes and measures the resulting damage.

Having developed the proposed damage model over time, one could determine the time that damage accumulates to a level where the component or structure can no longer endure the damage and fails. Existence of any uncertainties about the parameters and independent variables in this thermodynamic-based damage model leads to a time-to-failure distribution. Accordingly, such a distribution can be derived from the thermodynamic laws rather than estimated from the observed failure histories.