High-Power Shape Memory Alloy Catapult Actuator for High-Speed and High-Force Applications

Abstract

Nickel-Titanium (NiTi) based shape memory alloy (SMA) wires are already often used in industrial actuator applications. Their high energy density allows the building of light-weight actuator systems with high forces using small installation spaces. Combined with the biocompatibility of NiTi, a huge field of applications can be covered by SMA actuated systems. In systems like emergency brakes or switch disconnectors, which require high forces as well as high actuation speed, the high-power capability of NiTi actuators is exploited. The presented work details the development and characterization of a giant power catapult demonstrator, that combines the high-speed and high-force capability of SMA wires. To illustrate the vast force, speed, and power potential of SMA wires, a bowling ball is launched from its resting position vertically into the air using SMA wires. For demonstration purposes, a target altitude for the bowling ball of 500 mm is chosen. With the height and the overall accelerated mass given, an actuation force F≅ 920 N is needed. The instantaneous energy release from the designed power source results in the targeted flight height and an overall peak power of P≅ 0.5 MW.