A high-efficiency and high-precision digital image correlation displacement post-processing method

Abstract

The invention discloses a high-efficiency and high-precision digital image correlation displacement post-processing method. The high-efficiency and high-precision digital image correlation displacement post-processing method comprises the steps of calculating of Gaussian point coordinates in all calculation template coverage areas, calculating of Gaussian point displacement in all the calculationtemplate coverage areas, and correction of the Gaussian point displacement. According to the high-efficiency and high-precision digital image correlation displacement post-processing method, post-processing is conducted on the displacement and the displacement gradient which are obtained by a traditional digital image correlation (DIC), thus the displacement precision can be improved by one orderunder the condition that the minimum computational cost is paid, and the high-efficiency and high-precision digital image correlation displacement post-processing method is a measuring method with high precision and high efficiency; the average value of the Gaussian point displacement after interpolation serves as a final displacement measurement result, thus the random error can be effectively restrained, and high robustness is achieved; and the measuring method only needs to conduct simple mathematical operation on the displacement and the displacement gradient which are obtained by the traditional DIC, a DIC core algorithm does not need to be changed, the programming complexity is low, and the measuring method is easy to realize.

Description

technical field [0001] The invention relates to a digital image correlation displacement post-processing method, in particular to a high-efficiency and high-precision digital image correlation displacement post-processing method, which belongs to the field of photomechanics technology. Background technique [0002] Digital image correlation (DIC) is an optomechanical method based on modern image processing technology, which is measured by matching the gray value of speckle with strong recognizability in the image before and after deformation. Because of its advantages such as loose requirements on the test environment and the ability to obtain full-field displacement and strain, DIC has been used as an ideal deformation measurement method in many fields. [0003] Based on the research results of domestic and foreign scholars on the DIC sub-pixel algorithm and its influencing factors, the current DIC algorithm has been able to meet the accuracy requirements of conventional ex...

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Problems solved by technology

[0003] Based on the research results of domestic and foreign scholars on the DIC sub-pixel algorithm and its influencing factors, the current DIC algorithm has been able to meet the accuracy requirements of conventional tests in uniform deformation measurement

However, in the non-uniform deformation measurement of heterogeneous materials, the measurement deviation is relatively large, which cannot meet the high-precision full-field measurement requirements of heterogeneous materials

The main reason for the increase in measurement deviation is the under-matching of the first-order calculated template shape function based on the assumption of constant strain and the real displacement field

In order to improve matching, the existing solution is to reduce the size of the calculation template or increase the order of the shape function of the calculation template. The order will significantly increase the computational complexity of DIC and the sensitivity to image noise, which cannot meet the measurement requirements of high efficiency and high robustness

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