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

Abstract

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).

Modelling and simulation of a novel shape memory alloy actuated compliant parallel manipulator

“…The advantages derived from using the commercially available finite element packages are enormous. FEM analysis of SMA adaptive trusses [24], fuel-powered SMA actuator system [25], superelastic nitinol stent [26], NiTi stent and spinal vertebrae spacer [27], superelastic tubing [19], SMA strip actuator [28] and design of nitinol components [29] using ABAQUS have already been documented well in the literatures. Similarly, FEM of a SMA actuator [30], active vibration control of smart structures [31], and SMA micro-actuators with large deflection [32] using ANSYS have also been reported.…”

Comparative study of robotic artificial actuators and biological muscle

“…Another challenge is the low efficiency, which is approximately 10% theoretically and usually less than 5%, in practice; these values are much lower than the efficiency of biological muscle (Figure 7(a)). 108,115 Most SMA actuators are based on a spring configuration but the stress distribution is not constant over the spring cross section, which require a larger volume of material to be heated or cooled for the same output force and further reduces the actuator's efficiency. For optimal use of the NiTi SMA, a straight wire configuration is recommended due to a greater amount of work generated from less material volume.…”

“…118,153 The high strain and stress produces a high work density of 3.4 MJ/m 3 and a high specific power of 3.6 kW/kg. 53,65,114,115 The strain rate of DEAs is 450%/s due to the charges' quick response to an electric field. Furthermore, due to its simplicity and low modulus, this DEA is suitable for applications where mechanical compliancy and compact sizes are essential.…”

“…118 The actuation efficiency ranges from 60% to 80%; this high efficiency is primarily attributed to the direct transformation from electric energy to mechanical energy. 114,115 However, the high voltage used to drive the DEA is unacceptable in various applications and enforces an external electric source. 154,155 A large dielectric constant that corresponds to a greater capacitance is desired, which reduces the actuation electric field.…”

Wavelength Dependent Remote Power Supply for Shape Memory Alloy

“…The need of a contactless (remote) power supply source (Boeij et al, 2008) is increasing significantly in the field of Micro-Electro-Mechanical-System (MEMS) due to the difficulties faced by using electrical energy for example the size of batteries for a fully autonomous micro-system or the presence of wires in the working area of the micro-actuator. Jun et al (2007) presented a fuel-powered SMA actuator system to reduce or eliminate the dependence on electrical power supplies. Another possible way for remote supply (with no wires in the working area of the micro-actuator) is to use laser sources.…”