Research On Identification And Control Of Satellite-launcher Interface Load

The load characteristics of spacecraft cabin interface, docking interface are important bases for structure design of spacecraft. The spacecraft is prone to "over testing" phenomenon in ground vibration test. The Force Limited Vibration Test is the main method to solve ?over testing?. All of these have put forward an urgent need for the study of spacecraft dynamic interface force( i.e. DIF) identification. A identifying method based on continuous strain field of attachment is proposed in current study. And this method has been checked by finite element simulation and equipment testing.The main works and results are as follows:(1) Deriving the load identification method according to the thin plate assumption. Discreting the attachment to a lot micro cells. According to the thin plate assumption in elastic mechanics, radial stress and strain of each element are zero. Strain detecting points are arranged on the periphery of the attachment. Based on the changing strain field during launching, the six degree of freedom DIF can be identified. Due to the requirement of industry engineering, the discreted equation can be derived.(2) Verifying the validity of the method by finite element simulation. The result of simulation shows that, static identification errors of six degree of freedom load are not exceeding 7%, dynamic identification errors of six degree of freedom load are not exceeding 10%. During launching, the baffle plate?s influence is equivalent to a concentrated force applied to the attachment. But this wouldn?t affect the accuracy of the load identification. It shows that the load identification method can effectively avoid the influence of baffle plate and backpanel. According to the requirement of industry engineering, an optimization scheme for reducing the strain detection point is proposed. The result shows, static identification errors of six degree of freedom load are not exceeding 12%, dynamic identification errors of six degree of freedom load are not exceeding 20%. Finally, the sensitivity analysis is conducted.(3) Construct a set of interface load identification system for spacecraft, and verifying the load identification method by equipment testing. The static testing result shows, only one identification error is 20%, and the error of the other load identification is less than 10%. The error of load identification becomes smaller with the increasing of applied load. The strain change at the individual strain detection point is very small when applied a smaller load. Existence of the strain gauge drift phenomenon results in the error of strain data detection. When the larger load is applied, the error of the strain gauge drift is reduced, and the detection error becomes smaller.. Transforming the testing result from time domain to frequency domain and the result shows, the load identification method can effectively detect the frequency and amplitude of the peak and most of the amplitude error is less than 10%.