Research On The Excitation And Dynamic Characteristics Of Micro Cantilever Beam

Micro size structures are widely used in nonconventional environment, which requires their dynamic characteristics to be higher than the macro structures. The macro structure vibration measurement system can not meet the effective excitation and vibration measure of micro structures. According to the actual need, this thesis constructs a testing system combined piezoelectric based excitation with Doppler laser technology. Realize effective excitation of seven order natural vibration and extraction of modal parameters on micro cantilever beams, explore the influence of different section thickness changes on dynamic characteristics. The research works as follows:(1)Excitation methods, vibration testing technology and experimental modal estimation methods on microstructure are reviewed. The extiation methord based on piezoelectric ceramic and Doppler interference principle are introduced in detail. Complete selection of all the parts and the whole build of vibration testing system. Design a contrast experiment of micro cantilever beams and select a feasible method control the thickness. Calculate changes of natural frequency by thickness influence of the cantilever beam with finite element. The simulation presents that the effect of tiny changes in the wide dimention on the test result can be ignored.(2) Error model of frequency response function testing is build, by which choose a reasonable FRF estimation. Introduce in the least squares complex index method for modal analysis, establishment of a pole stable map and reasonable selection of pole based on modal judgment standard, realization of the modal parameters calculating. Complete extraction of modal parameters of different thick micro cantilever beams. Investigate the section thickness changes on the influence of natural frequencies.The research work of this thesis improves the micro size structure modal parameter extraction experiment method, which has certain significance on the dynamic characteristics testing technology development.