Study On Numerical Solution Method Of Measuring Two-Dimensional Stress Field Using Photoelastic Method Of Digital Hologram

Photoelastic method is one of the most important means of testing in experimental mechanics. Photoelastic method was injected new blood with the rapid development and a wide range of applications of optoelectronic components. In the modern, as a kind of practical and high reliability of testing methods, optical measurement mechanics plays an important role in engineering application and it also solves many problems of engineering, with the maturing of digital image correlation technology. There are many disadvantages and problems in conventional holographic photoelastic method, such as the arithmetic line stripes and line stripes at the same time there, mutual modulation, making it difficult to fringe analysis and not easy to measure and other problems. In order to solve these problems, Li Junchang, Xu Wei, etc put forward the reference light polarization rotation direction of digital holographic photoelasticity two-dimensional stress field detection method by applicatting traditional holographic photoelasticity technique combined with modern digital image correlation technique. With the basic completion of the experiment, We obtained experimental hologram image, the object light and reference light image for computing applications. There are some new problems came,which caused a lot of trouble to our follow-up work. For example, the captured digital image processing of the holographic image, nonlinear problems of image intensity equation, the solution of nonlinear equation and the problem of how to obtain the phase difference.The accuracy of digital holography photoelastic method of two dimensional stress field on rotation reference beam polarization direction is verified in this paper. The works in details are summarized as follows:1. The basic theory and procedure of the digital holography photoelastic method of two dimensional stress field on rotation reference beam polarization direction are applicated in this investigation.The information distribution images of experimental light intensity were got by shoting on epoxy resin specimens we newly purchased. Matlab soft was used to simulate the information distribution image of three-point bend specimens theoretical light intensity and then to determine the effectiveness of the experimental images.2.The static problem of structure of three point bending specimen epoxyin is analyzed by using Ansys soft, and its standard stress field distribution image is obtained. Thus a reference value of the theoretical solution can be given for the follow-up results of the stress.3. According stress distribution, the light intensity information distribution equation of these points can be simplified by using the distribution of points on the boundary of the specimen. It was further simplified when images of the rotating reference beam angle on its zero degrees. Then we get the boundary stress values and the relative error is calculated.4. We select any three points that no boundary distribution, on which its light intensity values were extracted from the four images and then we got four equations. The cosine of phase difference was got by the improved Newton iterative method for solving the four equations, and it was compared with the phase cosine values of finite element simulation.