Vibration Measurement Research Base On 3D Digital Image Correlation Method

Based on that the properties of the composites was gauged by vibration measurement and Nondestructive Testing as the breakthrough point, this paper expounds the current common principle of measurement of the vibration measurement method, after fully analyzes the advantages and disadvantages, try to take 3D digital image correlation method into the vibration measurement field. 3D-DIC is a measurement method which by means of contrast the space coordinates of sample area and seed point bottom on the information that image obtained. It has the advantages of traditional optical measurement method including non-contact and full field measuring, and simplifies the experimental conditions, suitable for complex outdoor environment.Utilize the existing XJTUDIC material test analysis system for three dimensional full field strain as the foundation, through improvement of system equipment, including mark angle, set the acquisition frequency and so on, solved that keep two camera data acquisition synchronization problems under the high-speed, set up vibration measurement system based on 3D digital image correlation method. On this basis, utilize the traditional sensor measuring method to measure the vibration of the specimen at the same time. By comparing the measured amplitude data and vibration frequency, observe the displacement curve with time and its waveform after the Fast Fourier Transform. The conclusion that the method based on three-dimensional digital image correlation is feasible to measuring vibration can be obtained.Due to the deviation of measurement, this thesis also gives the optimization scheme to improve the accuracy of the measured vibration. Measuring angle was determined by the regression analysis and measurement of the amplitude of correlation, and then calculate the correlation coefficient under every Angle, thus it is concluded that the amplitude of the optimized data; Through Fourier fitting grouping method to improve the precision of the measured vibration frequency, the fitting degree increased from 0.7955 to 0.9867, standard error decreased from 0.07638 to 0.01614, error rate from 1.4% to 0.28%. Finally based on the Matlab GUI to write a paragraph at the same time can finish the analysis of measurement data processing and calculation software.This study for vibration measurement provides a new, reliable and effective method, based on vibration analysis will greatly extend the scope of the use of the method of digital image correlation method.