<title>On-orbit experiments and applications of shape memory alloy mechanisms</title>

Abstract

Spacecraft require a variety ofmechanisms to accomplish mission-related functions such as deployment, articulation, and positioning. Current off-the-shelf devices such as pyrotechnic separation nuts, paraffin actuators, and other electromechanical devices may not be able to meet future satellite requirements, such as low shock and vibration, and zero contamination. The Air Force Research Laboratory (AFRL), with corporate and government partners, has developed Shape Memory Alloy (SMA) spacecraft release mechanisms and hinges as alternatives. In order to meet future goals, the SMA devices have been designed to reduce shock and vibration, reduce parts, and eliminate pyrotechnics. This paper will focus on descriptions and results of on-orbit SMA mechanism experiments and applications. AFRL has flown SMA release devices as part ofthe Shape Memory Alloy Release Device (SMARD) experiment on MightySat I. The SMARD experiment, that compared the shock and release times oftwo SMA devices with those of current off-the-shelf devices, was conducted in May 1 999 with extremely successful results. In addition, four AFRL funded SMA release mechanisms successfully deployed the Air Force Academy FalconSat spacecraft from the Orbital Sub-Orbital Program Space Launch Vehicle (OSP-I) in January 00. AFRL has also conducted an on-orbit experiment with SMA hinges. The hinges were flown as part of the Lightweight Flexible Solar Array (LFSA) program, that was a joint AFRLIDARPA/NASA/Lockheed Martin program to develop innovative solar array technologies. Six SMA hinges were launched as part of the LFSA experiment on the Space Shuttle Columbia (STS-93) in July 1999 with successful results.

Functional properties of TiNi conical working elements in the holding and release device

“…One of the promising devices types are SMA holding and release devices for space applications [Razov and Cherniavsky, 2003;Hartl and Lagoudas, 2007;Rongqiang et al, 2016]. SMA holding and release devices have characteristics better than classical pyrotechnic devices [Peffer et al, 2000]. In connection with these control tasks, it is necessary to know the dependence of their functional properties on the largest possible number of initial and external parameters for each working element made of SMA [Collado et al, 2014;Hartl et al, 2015].…”

Research on a low-impact unlocking trigger device of heavy load based on shape memory alloy fiber

“…To overcome the limitations of the traditional pyrotechnic devices, new joining connection and separation technology based on smart materials has been developed, 2 and the locking mechanism of many new joining mechanism has been developed, including shape memory alloy (SMA) release devices, [3][4][5][6] paraffin drive devices, [7][8][9][10] thermal cutting devices, 11,12 and other devices. 2,13 All these devices have been tested in space flight and successfully applied to multiple models. In these smart materials, the memory alloy has the highest working density 14 (it is 100 times the working density of the motor), and it can lift weight 100 times heavier than itself.…”

Functional verification and performance tests of an ultra-low shock non-explosive actuator for hold-down and release mechanisms for space applications

“…1 Pyrotechnic-based release actuators, a wellestablished solution in this overall domain, despite having a good mass to preload ratio, generate high shocks and are a source of contamination, a good example being the pyrotechnic device mentioned by Peffer et al 2 that with a mass of just 120 grams generates a shock acceleration peak of about 7200 g. In addition, they require heavy and costly safety and handling procedures, and are not reusable. 3 All these aspects generate significant constraints at both platform and equipment levels in all phases of the development and implementation into a spacecraft. This is even more critical for small satellites because of the close proximity of the equipment to the shock source.…”