Beyond Miner’s Rule Part II: Free Energy Damage Equivalence Applications

In part I of the paper published [1] last year, we extend the concept of damage originally developed empirically by Miner, using the concept of thermodynamic work and free energy. We first explain the equivalency of free energy to damage where a products free energy is the amount of useful work that a product can deliver. Knowledge of this provides useful lifetime estimates. We develop ways to measure the free energy in products to help assess its lifetime. The main approach is to use what we call a product's “Ultimate” work energy. In this paper, we explore practical applications in the area of fatigue and battery cycle life. Often when a new approach comes along, it is not easy to fully appreciate its applicability. Therefore, in this paper we will provide these new added examples applied to Aluminum fatigue and battery cycle life; These somewhat different areas 1) fatigue of metals and 2) an energy device, allows one to gain deeper insight into the free energy approach to determining a products useful life time. This will exemplify the efficiency of the “Ultimate” work energy damage equivalence approach for doing common but challenging problems. Example illustrate that tools like the SN curve while obviously illustrative, are not necessary the best way to characterize materials, as well this approach is anticipated to reduce experimental measurement time. If materials engineers instead of publishing SN curve data would instead provide tables of materials' free energy say in Joules, this would have more to offer in assessing useful life.