Based Virtual Instrument Vibration Testing And Modal Analysis System

Experimental modal analysis is an important method to identify the structural parameters,and plays an important role in the structure dynamic design and fault diagnosis.Comparing with traditional instruments, virtual instruments are more flexible and easier to expand.It has important teaching and engineering value to research the method to improve the operability and efficiency of experimental modal analysis system and to develop an experimental modal analysis system which has low cost and good interaction with virtual instrument technology.This thesis has done many researches on the basis theories of modal analysis, especially for the algorithms of modal parameter estimation, model order determination and real & unreal modal identification. In order to improve the use efficiency of the system, it analyzes the accuracy when use different modal parameters to fitting the measured curve, and proposes a method to extract all the real modals at one time which use different modal combinations to fit the measured curve and remove the un-real modal automatically. The experiment shows that this method can extract all the real modals.Based on the research on the theories and testing process of vibration testing and experimental modal analysis,and the experimental modal analysis software at home and abroad, it develops the Vibration Testing and Experimental Modal Analysis System in the platform of Labview. According to the fact that most of domestic softwares of modal analysis are often complicated in structural modeling and not very well in mode animation, this thesis achieves structural model inputs by reading the structural model which is created by other modeling software,such as SolidWorks, Pro/E and so on, with VRML (Virtual Reality Modeling Language Virtual Reality Modeling Language);and realizes the function of mode animation well by using the technology of ActiveX to achieve real-time data exchange with a third-party software and display mode animation real-time in the third-party software.Finally, four practical application examples have been done to test and verify the system's software and hardware.The results show that the system runs stably and reliably, the software algorithm is correct and effective.The system can be used to test and analyze common dynamic signals, or as the basis of further studies about modal analysis theory, it can also be used to analyze certain structure's modal parameter with the hammering method.