Research On The Identification Method Of Base Acceleration Excitation On Satellite

Dynamic load information is the key issue for the structural design of a spacecraft such as a satellite.Due to restriction of measurement technology,the complex excitation information at the interface between satellite and rocket during the launch process cannot be accurately obtained by direct measurement.Therefore,the structural dynamic response which is more convenient to measure is commonly adopted to identify the external excitation of the structure;this is an indirect method regarded as the dynamic load identification methodd.Lateral load exists during the launch process,which will generate bending moments and shear forces at the circular interface between satellite and rocket and further lead to the non-uniform characteristics of the interaction force.Therefore,to investigate the identification method of non-uniform distributed dynamic load is very important.This paper focuses on the research of the identification method of acceleration excitation acting at the base of satellite structure.By identifying the basic excitation acceleration signal from structural response,the distributed dynamic load at the interface between the satellite and the rocket can further be predicted.The method proposed in this thesis can provides accurate dynamic load data for the lightweight design of the satellite structure.The main research contents are as follows:(1)Research on the time domain distributed dynamic load identification method based on impulse response function and B-spline functions is conducted.The impulse response function is used to establish the transfer relationship between the excitation and the system response in time domain,and B-spline functions are adopted to represent the distribution function of the dynamic load.Combined with the finite element method,the distributed dynamic load is identified.The effectiveness of the identification method is verified by numerical simulations,and the influences of noise levels,measurement points and B-spline control points,etc.on the accuracy of the identified results are discussed.(2)Research on frequency domain distributed dynamic load identification method based on inverse pseudo excitation method and B-spline functions is conducted.The frequency response function is used to establish the transfer relationship between the excitation and the system response in the frequency domain,and B-spline functions are adopted to represent the distribution function of the dynamic load.Combined with the finite element method,the distributed dynamic load is identified via the inverse pseudo excitation method.The feasibility of the proposed method is verified by numerical simulations,and the influences of noise levels,measurement points and B-spline control points,etc.on the accuracy of the identified results are discussed.(3)The manufacture and finite element modeling of both the satellite structure model and force measuring tool are conducted.The finite element model updating on the satellite structural model is carried out by using the modal test data.A high fidelity finite element model which can accurately reflect the dynamic characteristics of satellite structure is obtained.(4)Based on the updated satellite structure model,the vibration test under the basic excitation is carried out by using the vibration table.Both the time-domain and frequency-domain distributed dynamic load identification methods are verified by using the measured acceleration signal on the satellite structure,which provides experience and reference for the practical engineering application of dynamic load identification method.