Based on magnetic levitation principle, the magnetic bearing flywheel is a new type of inertial actuator used in satellite attitude control. A locking device was used to eliminate the gap between the rotor and stator of magnetic bearing flywheel so as to protect it from shock and vibration damage during launch phase. The present pyrotechnical or motor actuated locking devices have the disadvantages of high shock, large size and un-resetable. A prototype shape memory alloys (SMA)actuated locking device for small space magnetic bearing flywheel was developed in this investigation. A method and procedures to design the actuator element based on Liang-s constitutive model was presented. Then the SMA locking device was assembled and the function, environment and vibration tests were carried out. Test results show that the device can complete lock function within 6 s and release function within 1 s under satellite power supply of 28 V. It can also undergo the environment and vibration tests which simulate the launch phase. It is concluded that the new SMA locking device owning advantages of great locking force, small size, low shock and easy to reset has a potential use in space engineering.
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