Testing the frequency response of a mounting plate with a spring-loaded rotor

In order to work properly, all devices on board a spacecraft, such as telescopes, cameras, sensors, aiming devices, etc., must be able to correct internal perturbations. Spacecraft dynamics is mainly determined by the rotation of on-board rotors. In this study, a test mounting plate is used to model mechanical vibrations of the spacecraft load-carrying structure in the case when the flywheels of the spacecraft flight control system are rotating. Two vibration modes of the mounting plate with a spring-loaded rotor are analyzed in the frequency range from 10 to 30 Hz. Rotating unbalance is ignored. A technique for testing the frequency response of the mounting plate is proposed. A computer DC cooling fan is chosen as a rotor. The required moment of inertia is provided by wrapping an adhesive tape. It is shown that the level of noise in the signal measured depends on the place of the rotor frequency in the frequency range under. consideration. The mounting plate with a spring-loaded rotor is analyzed by the finite element method using MSC.Nastran.Rotordynamics. The rotor attachment to the mounting plate is modeled by the set of six springs corresponding to the six degrees of freedom. The stiffness of the rotor attachment to the plate is computed by minimizing the difference between the calculation and experimental results. The Campbell diagram of the mounting plate with a rotor is presented. The difference between the calculation and experimental results is within 8 %.

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