The Design Of Experimental Modal Analysis System For Mechanical Structure

Experimental modal analysis is based on the known system, and get the system frequency response function or impulse response function on the basis of mathematical processing between the input and output data, then obtain themodal parameters of the system through the modal parameter identification method. Experimental modal analysis has good controllability, good testing repeatability, high modal parameter identification precision and reliability.Thus it plays an important role and a wide range of applications on structure design modification, damage identification. Therefore, designed with high structural modal identification precision, high efficiency and fast experimental modal system is an important topic of the engineering research.In this paper, the principle of experimental modal is In-depth study. To optimize algorithm for multiple reference least squares complex frequency domain method.This methord set the frequency response function of the variance as weighted function, enhence the quality of the frequency response function and improve the parameter identification precision. Put forward the automatic identification of modal optimal weighted grouping based on stability graph. Various calculation modal score group according to the modal frequency, damping ratio and modal vibration mode, pick up the the optimal modal based on the modal score, improve the filtering efficiency, reduce the subjective influence on stability of modal choice, more accurate extraction of structural physical mode.Set Up experimental modal analysis system, and design the overall framework of the software. According to the actual demand of the mechanical structure Experience analysis design the framework of the moda experiencel analysis software system. And using of modularity and tab sheetform, to design the modules of modal analysis system.and design the the universal two-dimensional display, 3D structure model displays and stabilization diagram display. The experimental modal analysis system including the structure modeling, data acquisition, data processing and selection, modal identification, model verification and modal animation. according to the signal analysis and processing principle, test specific requirements, application experience and other aspects of a comprehensive consideration, design the experental modal analysis system application to meet the the basic professional principle, test requirements.Use the developed experimental modal analysis system to identify the modal parameters of steel frame structure based on wire and WSNs acquisition. Through the modal analysis system setting up, structure modeling, data acquisition, modal identification process, and then use the automatic mode selection function to identify the frame structure’s natural frequency, damping ratio and mode shapes. Compared the results of modal analysis system designed with LMS, it is proved that the system can effectively identify the modal parameters of the structure with the recognition precision and higher efficiency,and validate the feasibility of the correctness and engineering application of the modal analysis system based on wire and WSNs acquisition.Finally, the works of this thesis were summaried, and the future prospect of Operate Modal Analysis technique is also discussed.