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Reaction wheel assemblies are one of the most important microvibration sources on typical modern satellites. In this paper microvibrations induced by a cantilevered reaction wheel assembly are modelled and validated against microvibration test results. The disturbance model is developed using energy method. A microvibration measurement platform is designed to measure its disturbances. Disturbance test results are analyzed in detail. The peculiar dynamic characteristics such as nonlinearity and high damping of harmonic responses in the test results are discussed. Estimations of damping values used in the disturbance model are introduced. A new method developed to model harmonic excitations is discussed. Furthermore, novel methods to identify harmonics and extract model parameters from test results are presented. The empirical modeling method developed for broadband noise excitations are also introduced and validated.

A dynamic model of power split transmission system with face gear and cylindrical gear is established. The factors including time-varying mesh stiffness, torsional stiffness, supporting stiffness, and clearance are considered in the model. The influence of the torsional stiffness of compound gear shaft on the load sharing coefficient is analyzed. The results show that the influence of the torsional stiffness of the compound gear shaft is obvious. Because the torsional stiffness of the output gear components is larger and the torsional stiffness of the input gear is smaller, so the input stage's deformation coordination ability is strong. Therefore, with the increase of the torsional stiffness of the compound gear shaft, the load sharing coefficient of the power input stages is improved, but the load sharing coefficient of the split torque stages and power confluence stages is worse. Hence, the torsional stiffness ratio of the transmission shaft should be rationally allocated under the condition that the torsional stiffness of the compound shaft is small.