Nonlinear vibration analysis of spacecraft with local nonlinearity

Most spacecraft are usually assembled from some simple substructures by different kinds of connectors, which include various kinds of joints and hinges. Most of the connectors have properties of nonlinearity, and can strongly affect the dynamic characteristics of spacecraft. Mathematical models of such spacecraft usually have a large number of degrees of freedom (DOFs), but their nonlinear connectors are generally spatially localized. In general, it is impractical and time-consuming to directly calculate the frequency response of the spacecraft using current methods. To enhance the calculation efficiency of the frequency response, an improved approach is proposed in the present paper. With describing functions (DFs) and linear receptance data, the kinetic equations are firstly converted into a set of complex algebraic equations whose dimension is only associated with nonlinear DOFs and interested DOFs. Subsequently the number of iterative equations is reduced and only related to nonlinear DOFs. Hence the improved approach can be applicable to large-scale and complicated finite element (FE) models. An FE model of a satellite with some nonlinear joints is used to show and demonstrate the usefulness of the proposed method. Besides, the effects induced by nonlinear joints on payloads’ vibration of the satellite are discussed.