Shape Memory Alloy Design for a Lightweight and Low Stow Volume Expandable Solar Concentrator

Shape memory alloys (SMAs) offer a lightweight, compact choice for expandable solar concentrator reflector components due to their high energy density capacity capable of actuating into the designed shape once released from stow configuration. By processing three SMA systems into triangular chips, with excellent thermomechanical stability, seamless integration into innovative actuation designs becomes feasible. These designs can enhance thermomechanical responsiveness and minimize energy consumption, weight, and mechanical complexity of the systemIntroducing Ni-to-Cu in the NiTi SMA composition results in an SMA with a narrow hysteresis when compared to standard binary NiTi SMAs. In this study, NiTi and NiTiCu SMA compositions were thermomechanical processed using conventional methods such as hot rolling at 800°C to produce plates and cut into triangular chips with an edge length of 1.5, 3, and 6 in, (3.8, 7.6, and 15.2 cm). Each processing step undergoes comprehensive characterization to monitor microstructural and thermomechanical property changes using differential scanning calorimetry, microscopy, spectroscopy, and X-ray diffraction techniques. The NiTi and NiTiCu triangular chips were shape-set utilizing a custom-made apparatus and load to attain the intended curved surface with dimensions specified for a reflector component within a solar concentrator. These chips were produced from NiTiCu button, as well as commercially available NiTi SM495 plates. The chips were then thermomechanical cycled until stabilized when necessary.