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Development and validation of microvibration models for a satellite reaction wheel assembly

By Zhe Zhang


Microvibrations are a critical concern on satellites equipped with instruments with high stability requirements. Amongst many sources of microvibration onboard, reaction wheel and momentum wheel assemblies are often considered the most significant. This thesis presents the development and validation of microvibration models for a cantilever configured wheel assembly designed with a soft-suspension system. Wheel assembly induced microvibrations under hard-mounted and coupled boundary conditions are studied. In particular, the wheel assembly semi-analytical microvibration model in a hard-mounted boundary condition is developed with harmonic excitations and the traditionally ignored broadband noise excitations are included. Some peculiar dynamics such as nonlinearity in the motor and high damping of the soft-suspension system are observed from the hard-mounted measurements conducted on a bespoke dynamometer.<br/><br/>Modeling strategies for these peculiar dynamics are developed and implemented in the wheel assembly microvibration modeling. This includes a systematic approach to extract stiffness and damping values of the suspension system, considering nonlinearity and high damping from measurements. The microvibrations produced by the wheel assembly in a coupled boundary condition are studied using a seismic mass to support the wheel assembly. A coupled microvibration measurement system, which allows the wheel assembly interface loads to be reconstructed by measuring the response accelerations on the seismic mass, is designed, built and validated. In addition, the wheel assembly driving point static and dynamic accelerance are measured and analytical expressions of the driving point dynamic accelerance are derived. The coupled microvibrations are predicted with wheel assembly static accelerance, dynamic accelerance and the standard method (i.e. no wheel accelerance). The predicted results have shown that the method developed in this thesis which uses the wheel assembly dynamic accelerance accurately simulates the microvibrations observed in practice

Topics: TL
Year: 2013
OAI identifier:
Provided by: e-Prints Soton

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