Research And Application Of Digital Image Correlation Detection Of Structural Vibration

Vibration is very common in life,and various vibrations can be seen in various fields.When people are designing structures or materials,they must consider the vibration characteristics of the structure,otherwise damage due to vibration will inevitably occur during use.Therefore,we need to perform vibration tests on the structure to understand the vibration characteristics of the structure.Vibration test methods can be divided into contact and non-contact methods according to the contact form.The non-contact method has recently begun to be widely studied because of its non-contact and full-field measurement characteristics.However,when using digital image correlation methods,it is inevitable that various problems will be encountered.This article mainly conducts research based on the problems encountered in the application of digital image correlation,and promotes the application of this method to other fields.The specific content and conclusions of this article are as follows:(1)When using DIC for experimental modal analysis,the first thing to be solved is the synchronization between the hammer force signal and the high-speed camera.Therefore,a DIC-based vibration test platform is built here through related software and equipment,which can be used for subsequent structural vibration tests.It is mainly based on the Lab VIEW software to write the corresponding program to control the acquisition card.When the hammer is excited,the acquisition card sends out a trigger signal to trigger the high-speed camera to shoot.After that,the signal from the high-speed camera is used to control the acquisition card to collect the excitation force,thereby realizing the synchronization of the dynamic signal and the force signal.(2)After using DIC to obtain the vibration test signal,since the system does not have a related post-processing system,it is necessary to study the modal parameter identification method based on the subsequent signal processing of the DIC test.Therefore,based on the combination of singular value decomposition and nonlinear least squares iteration,a modal parameter identification method that can be used to process DIC vibration test data is proposed.First,the accuracy of the method is verified by the cantilever aluminum plate.Compared with other parameter identification methods,such as the Polymax method in the LMS,the rational fraction polynomial method,the forced normal modal test and the working deformation analysis,the aluminum plate can also be more accurately identified.The modal parameters.In addition,the application of the car bonnet also makes this method suitable for parameter identification of large and complex structural parts.(3)Here,DIC technology is applied to the field of lightweight carbon fiber composite materials.The DIC vibration test is mainly applied to the material reverse seeking of carbon fiber composite panels.Based on the combination of the Rayleigh Ritz method and the multi-objective optimization algorithm NSGA-?,a method for inverse calculation of carbon fiber composite material parameters based on DIC vibration test is proposed.First,a sensitivity analysis was carried out,and it was found that the natural frequency is closely related to the material constant.In addition,the influence of the number of objective functions constructed by natural frequencies on the accuracy of material parameter inversion is discussed,and it is found that the multi-objective optimization algorithm and the use of natural frequencies to construct an appropriate number of objective functions can reduce the error of material parameter identification.In addition,the result of NSGA-? identification was compared with the result of GA identification,and it was found that the material parameter identification result of the constructed three-objective function was closer to the real value of the material than the result of GA algorithm identification,and the relative error of the identification result was smaller.Finally,through the application of graphite/epoxy resin composite materials,the accuracy of the proposed method is also verified.