Experimental Research On The Damping Characteristics Of The Spacecraft Brackets

The bracket is the main support for instruments in the spacecraft, it has great impact on the related instruments and can help them work safely and reliably.However, the damping parameters of the bracket are hard to be determined,it may cause the FEA results of the brackets far from the experimental ones.In this thesis, an experimental research on predicting the damping characteristics of the spacecraft brackets is designed.It can not only provide proper parameters for dynamics simulation at the design stage,but also ensure the veracity and reliability of the calculation results.Therefor,it has significant engineering application value. Specific work is as follows:(1) Six structural damping characteristics identification methods based on the experimental data are studied.In detail,the least squares complex exponent method, ARMA model time-series analysis method and eigensystem realization algorithm(ERA) are for the time domain; the rational fraction polynomial, orthogonal polynomial fitting(OPF) and vector fitting(VF) are for the frequence domain. After taking a simulation analysis of a cantilever by driven-base excitation with noise, it is concluded that the error of damping identification results of OPF and ERA is relatively smaller to other methods.(2) For three typical spacecraft brackets, an orthogonal experiment method is applied to analyze the influence of different factors on the bracket damping characteristics, such as framework dimensions, connection boundary, and equipment weight. An experimental platform is set up by taking a single axial vibration table to supply the base excitation.By fitting measured data, modal parameters fitting results are basically consistent, validate the validity of the various methods.(3) The multiple quadratic regression analysis is used to carry out the damping models based on the measured damping value, the influence of different factors on the bracket damping characteristics is revealed.Finally, a verification test is used to prove that the damping models and the design of the testing scheme are feasible.