Study On Measurement Of Out-of-Plane Displacement Based On Optical Detecting Technology

With the rapid development of scientific research,the demand of high-precision large-size workpiece is growing in the manufacturing industry,and the detection of out-of-plane displacement is also increasing,which means a new out-of-plane displacement detection method been proposed to be important significance.Optical detecting technology has become an important method to measure out-of-plane displacement owing to its non-destructive,fast and accurate.There are many types of out-of-plane displacement detection method,which can be divided into geometric optics method,interference method and digital image correlation method.However,the current detection methods are hard for practical application of Engineering.Based on the single camera digital image correlation method,the rubber plate and the glass plate out-of-plane displacement fields are experimentally measured by using one CMOS camera.The experimental measurement out-of-plane displacement fields based on single camera digital image correlation method consist of spraying artificial speckle,collecting digital images,performing images correlation calculation,calculating subpixel displacement field,calculating strain,and finally obtaining the out-of-plane displacement field.The experimental results show that the out-of-plane displacement fields of single camera digital image correlation method basically agree with the loading out-of-plane displacement value.which means that the single camera DIC method can measure the out-of-plane displacement field.However,based on the experimental device and the conditions in this study,the out-of-plane displacement should be greater than 2mm,and smaller out-of-plane displacement can not be detected.In this research,an optical detection method is proposed to measure the out-of-plane displacement,which has the characteristics of full-field detection and high detection speed.This method is based on multiple reflections of light between two mirrors.Multi-level digital images formed by multiple reflections of the light emitted by the identification point can be seen by the CMOS camera and stored as deformation information.Digital images of different target mirrors were obtained through experimental studies,on the one hand,if there is no change among the digital images means that no out-of-plane displacement,on the other hand,if there is a change among the digital images means that the existence of out-of-plane displacement which can be measured by comparing the images.The basic theory of geometric optics is completed in this research,and the correspondence between the bitmap of multi-level objects and the out-plane displacement is deduced.Besides,two planar optical devices are designed,which can be used to adjust the magnification of small out-of-plane displacement.According to the experimental purpose,principle and condition,the design,processing,installation and debugging of the experimental device are completed.Experiments on the out-of-plane displacement measurement under a variety of loading conditions of the four-edge simple supported glass plate are carried out.The simulation results are obtained by ANSYS.The comparison results show that the experimental results of out-of-plane displacement based on geometrical optics detecting technology are basically consistent with the simulation results.The reliability of the experimental mothod is proved.A feasible and effective method for the rapid detection of medium and large-sized glass plates is proposed which can provide important references for the study of out-of-plane displacement optical detecting technology.