THE DEVELOPMENT OF A SELF-RESETABLE, LOW-SHOCK HOLD-DOWN AND RELEASE MECHANISM

Abstract

Satellite systems are often equipped with deployable structures. Such structures (e.g. solar arrays) are stowed and preloaded to the structure of the satellite prior to launch. The preloading and the release are handled by hold-down and release mechanisms (HDRM). Many hold-down and release mechanisms are nowadays commercially available. The release bolt of the mechanism is the interface between the deployable structure and the satellites body. This bolt is released for deployment of the structure. Usually this bolt can be either fractured by a shape-memory alloy cylinder (SMA), by explosives, or it can be freed by internal kinematics to remove blocking elements holding the bolt in place to allow separation of the I/F. Those release methods are widely implemented in commercial products. The new HDRM technology developed at DLR termed CREAM (Collet Release Mechanism) omits those methods and instead fixes the bolt through a frictional mechanism. Several major improvements can be achieved by this strategy: simplicity in the design, low-shock characteristics or selfresetability. The frictional locking mechanism is realized based on a self-locking clamping device used widely in industry, but tailored to the needs of space applications. This mechanism allows unique simplicity in the handling of the device. This paper will start with a state-of-the-art review on existing hold-down and release mechanism. This shall identify individual advantageous and drawbacks of the different technologies. The major requirements for the development of CREAM are outlined afterwards. It further describes the CREAM technology in principle and continuous with the design description of the 1.5 kN CREAM HDRM model. The paper describes the prequalification of this unit and the outcome of the test campaigns. The commercialization process together with the industrial partner, DCUBED, is outlined at the end of the paper.