The Energy-Efficiency Dynamics of Materials: Strength, Toughness, and Fatigue — An EET Framework for Mechanical Performance

Materials are the physical embodiment of constrained-state energy. Their mechanical properties—strength, toughness, fatigue life—reflect the ability to store, dissipate, and reorganize energy under external loads. Yet current theories describe these properties through separate empirical frameworks (Griffith theory, Paris law, S-N curves) without a unifying first-principles foundation. This paper develops a framework within Energy-Efficiency Theory (EET). Starting from Yang's three causal-functional postulates, we propose that materials are constrained-state energy structures, and mechanical performance is governed by the competition between energy storage and energy release. The Energy-Efficiency Regulator…