Shape Memory Alloy Thermal Management in Aerospace

A shape memory alloy (SMA) activated thermal joint was developed for switching conduction paths on and off in space thermal control systems (TCS). Here, high force SMA compressive elements are used to make and break mechanical contact at a thermal interface to close and open thermal conduction paths between payloads and radiators. This enables protection against adverse heating in direct sunlight or the ability to hibernate to conserve power within the TCS in response to changing environmental conditions such as a lunar day-night cycle. First, low hysteresis NiTi-X (X: Pt, Pd, Cu) SMAs are developed to application requirements and evaluated for reducing power to actuate and/or passively responding to environmental conditions. Second, a thermal-mechanical contact, finite element method (FEM) model is developed to optimize size, weight, power (SWAP) and closed-to-open thermal conduction ratios through the thermal interface. Lastly, a flight-like thermal joint is designed, built and thermal-vacuum tested to validate the technology for commercial communication satellites and lunar applications. Results show active thermal joint capabilities that can outperform status quo solutions in SWAP by more than an order of magnitude with closed-to-open thermal conductance ratios exceeding 1000:1.