Phase-transition-driven lattice relaxation for artificial muscle actuation

Artificial muscles are commonly limited by a trade-off between achievable work density and actuation rate. We present a theoretical framework in which crystallographic phase transitions provide a lattice-relaxation work source for artificial muscle actuation. Mechanical output arises from thermodynamically driven phase evolution coupled to elastic compatibility with an external load, rather than from resonant or vibrational motion. The available free-energy density across the transition sets geometry-independent bounds on recoverable work density, while thermal transport imposes a characteristic time scale that limits actuation bandwidth. These energetic and thermal constraints combine to define a universal performance envelope separating high-work-density, low-rate operation from high-rate, low-work-density operation. The framework establishes general design principles applicable to phase-transition artificial muscles and micro-actuators across material classes.