Interface Dynamic Model Simplification For Satellite And Rocket System In Force Limited Vibration Test

The over-testing problem is mainly caused by the traditional method in which the acceleration spectrum was enveloped and used as the control spectrum of the vibration table.The engineers and scientists at home and abroad think that the force limited vibration(FLV) method is the best for overcoming the over-testing problem. NASA and ESA began to do the research on the FLV method very early,but the research of FLV method in our country is still at exploring stage.So further study on the FLV method is meanful for the space cause of our country.This paper implements the research on the over-testing problem of the aircraft. We built the dynamic system model by taking the test structure and the shaking table as the research object,then we deduced the formula of the acceleration of the table, the interface force and the acceleration response of the measuring points at the structure in the three modes which are the real environment mode,the acceleration control mode and the force control mode.The response amplify function in the acceleration control mode and the response amplify function in the force control mode have been defined.We discussed the cause for the over-testing problem and the frequency location in the acceleration control and force control mode.The dual control mode and its compensation mechanism for the over-testing problem have been defined and explained.By a simulation example,we explained the concepts,compare the results in the acceleration control mode and the force control mode and verify the theory mentioned in this paper.The efficiency of the FLV method depended on how to acquire the proper control spectrum of the vibration table.The formula for the interface force,acceleration and apparent mass of satellite-rocket system were derived by fixed interface component mode synthesis method.A model composed by the effective mass of the satellite and rocket was built.By simplifing the model and comparing the interface force and acceleration with the original model,the model was proved to be effective.The structure and the dynamical property of the force measurement device were introduced at last.The data from the satellite vibration test with force limited vibration method were analyzed and the FLV method was applied in the satellite test preliminaryly.