Structural Response Calculation On Wideband Nonstationary Signals Excitation By Wavelet Decomposition

Along with complication of large-scale engineering machinery's working environment,exciting load of its structure has become diversification.Signals of exciting load has become wideband and non-stationary from narrow band and steady in tradition.The dynamic responseof structure in the excitation of wideband and non-stationary signals becomes more and more urgently. In addition, with a substantial increase in accuracy of test equipment, the measurement of dynamic response of structure in this complex excitation load signal also becomes possible.With the development of computer technology, more and more finite element method applied to the variety simulation, analysis and calculation of dynamics.The first part discuss a variety of numerical methods commonly used for broadband, non-stationary signals excited by adaptive structural response calculations, and comes to the following conclusions: for the band, the calculation of steady-state excitation signal can get highly accurate results, however, for broadband and non-stationary signals incentive, it is difficult to get good results, even an error result. It is proposed based on signal decomposition and restructuring methods. The broadband, non-stationary signal is decomposed into narrowband signals of different frequencies, different frequency of excitation signals with different methods of calculation, the response and the original broadband, non-steady-state response excitation of the structure has obtained.Wavelet theory is the rise in recent years, a new signal analysis theory, one can achieve the time domain or frequency domain analysis of time-frequency localization method, known as the mathematical "microscope." In the second part, the research studies how to use wavelet transform method decompose broadband, non-stationary signal into different frequency bands of narrow-band, steady signal. Through wavelet signals'decomposition of different frequencies can be separately obtained by different methods of calculation of its response. The high-frequency signal also can be written to a linear combination of high-frequency wavelet basis, using the system response on wavelet basis, high-frequency response of the system can be quickly obtained. And then through the superposition principle the response can be measured.The third part research on with a broadband, non-stationary signal excitation, structural dynamic response of the numerical simulation time step selection principles, and the high frequency signal excitations translate into high-frequency response of wavelet bases, in order to ensure accuracy, computation time truncation selection principle.Finally, validated by experiment: in the excitation of non-stationary broadband signals, through the wavelet method, decompose the excitation signal into different frequency bands, and then obtained by superposition of the response of the linear system is indeed feasible .