Research Of Structural Modal Experiment And Parameter Identification For High Speed Vehicles Under Flying Environments

Since21st century, hypersonic flight technology has established itself as a newworld-wide focus on the development of aerospace technology. Though supported byvigorously by many countries, hypersonic flight technology has brought some technicalproblems which have not been properly solved yet.There are mainly two difficulties for flight vehicles’ test work under flyingenvironment. Firstly, high-speed flight can cause severe aerodynamic heat and noiseloads, resulting in extreme adverse working environments. The current measurementtechnology and sensor level can not meet the demands of high-temperature andbroadband testing. Secondly, due to the limitations in the telemetry transmissioncapacity of flight test, relevant structural data often only includes a small amount ofacceleration response measurement data from some key parts of the flight vehicle. Onthe basis of these two characteristics, this thesis makes a study on two key technologies,which are structural modal test technology under high-temperature groundenvironments and operating modal parameter identification(or Operating ModalAnalysis, OMA).In the thesis, structural modal tests of different excitations are firstly made on thetypical structure of metallic materials in high-temperature environment, and currentlyavailable test facilities are utilized to get relatively reasonable techniques. In addition,from the current OMA methods of time-domain and frequency-domain, this thesisselects the method of stochastic subspace identification and the method of lineartime-frequency representation, compiles Matlab programs, makes parameteridentifications respectively on the test results in time-invariant and time-varyingconditions, and identifies the natural frequency and vibration mode of the test structure.Furthermore, some discussions are also made on the application of improved stochasticsubspace identification on the time-varying modal parameter identification. Finally,widely-used means of data processing and algorithm are selected and integrated toconduct flight test data processing and the development work of modal parameteridentification software in MATLAB graphical user interface developmentenvironment(GUIDE).