Spacecraft require a variety of separation and release devices to accomplish mission related functions such as separation from the launch vehicle, deployment of solar arrays and other appendages. Existing technologies may not be able to meet mechanism requirements for future lightweight satellite programs. The use of pyrotechnics for example will expose fragile sensors and electronics to high shock levels and sensitive optics might be subject to contamination. SMA (Shape Memory Alloys) are one class of actuator material that provides a solution to these design problems. SMA's utilize a thermally activated reversible phase transformation to recover their original heat treated shape (up to 8 % strain) or to generate high recovery stresses (greater than 700 Mpa) when heated above a critical transition temperature. NiTiCu alloy actuators have been fabricated to provide synchronized, shockless separation within release mechanisms. In addition, a shape memory damper has been incorporated to absorb the elastic energy of the preload bolt and to electrically reset the device during ground testing. Direct resistive heating of the SMA actuators was accomplished using a programmable electric control system. Release times less than 40 msec have been determined using 90 watt-sec of power. Accelerometer data indicate less than 500 g's of shock were generated using a bolt preload of 1350 kgs. Consequently, SMA devices are an effective method of provide shockless separation.


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    Title :

    Shape memory actuated release devices


    Additional title:

    Startmechanismen mit Formgedächtnislegierung für die Raumfahrttechnik


    Contributors:
    Carpanter, B. (author) / Clark, C. (author) / Weens, W. (author)


    Publication date :

    1996


    Size :

    7 Seiten, 5 Bilder, 1 Tabelle, 2 Quellen




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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