The Dynamical Modeling And Random Responses Of A Bolted Acquisition Device Based On Model Updating

With the rapid development of the aerospace industry in our country, more and more electronic equipment are used in the spacecraft. The equipment always subjects to random vibration loadings during test, assembly and work. And the vibration in the equipment may cause several of failures. In order to guarantee the reliability of the electronic equipment, it is necessary to establish its dynamic model using finite element method(FEM). However, with the miniaturization, integration and complication of the electronic equipment, the model accuracy cannot meet engineering requirements for the uncertainty and simplified method in modeling process. Therefore, in order to optimize the structure and control the vibration of the electronic equipment in the spacecraft, it is very important to update parameters of the finite element model and to obtain both the inherent characteristics and responses of the electronic equipment.In this paper, an acquisition device in the spacecraft is considered as the research object. There are two steps of the method in this paper. The dynamic characteristic of the assembly part is studied first and then the dynamic characteristic of the integral structure is investigated. With reasonable simplification, the design variables and objective function are established by considering the results of sensitivity analysis and the modeling error of bolted connection. The material parameters of the printed circuit boards(PCBs) model are modified. The finite element model of the integral structure is established based on the above results. The accuracy of the model can be improved and the calculation time can be reduced according to the method. The dynamic properties of the integral structure are analyzed in this paper. The main achievements in this paper are as follows.Firstly, the simplified modeling method of PCB and the connection structure are discussed. A local finite element modeling method and the Boolean glue command are proposed to simplify the PCBs and the connection between the components, respectively. The finite element models of PCBs and the whole acquisition device are established preliminarily by ANSYS.Secondly, the sensitivity analysis method is studied by probabilistic design system(PDS) in ANSYS. The eigenvalue sensitivity values of PCBs to material parameters are calculated by using this method. Then the material parameters of frame, board, components, connecting plate and the mass of sensors are proposed as the design variables in parameter updating. And the frequency error and the diagonal of MAC matrix are used to form the objective function.Thirdly, the ANSYS optimization design method is investigated for model updating and used to update the parameters of three PCBs. The validity of the updated parameters is verified by changing the boundary conditions of the structure. The accurate finite element model of PCBs is obtained and the inherent characteristics of the PCBs are analyzed based on the above works.Finally, the accurate finite element model of the acquisition device is obtained by applying the updated material parameters to the acquisition device model. The mode and random vibration response of the acquisition device are analyzed by employing modal analysis and spectrum analysis module in ANSYS. The calculation of the response power spectral density and the root mean square value of some sensitive parts are proposed to analyze the characteristics of the acceleration and stress response, respectively. The results obtained in this paper can be a theoretical support for the structure optimization design and the arrangement of components.