Development of a fuel-powered shape memory alloy actuator system: I. Numerical analysis

This work (Part I) discusses the numerical analysis of a fuel-powered shape memory alloy actuator system (FPSMAAS) that utilizes fuels with high energy densities, such as propane, as its energy source and thus reduces or eliminates the dependence on electrical power supplies, such as batteries. The main component of the actuator, a shape memory alloy (SMA) element, operates as a heat engine and converts the thermal energy of fuel combustion to mechanical energy. The incorporation of the high energy density fuel and actuator control hardware and software inside the unit makes for a compact actuator system, requiring only low-power, digital actuator control signals as input. Due to the relatively high recovery stress and strain of SMAs, the compact actuator can provide significant force and stroke. Convection heating and cooling of the SMA also results in relatively high actuation frequencies. Finally, if the compact actuator is utilized in the context of a larger system producing excess parasitic heat, the energy density of the actuator subsystem increases. The numerical analysis of the SMA element/strip was conducted using commercial software, including FLUENT and ABAQUS. The goal of the analysis was to estimate actuation frequency and actuation strain. In addition, a multi-channel combustor and a micro-tube heat exchanger were designed and analyzed. These results were compared to experimental tests and measurements ( Part II).