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Half-subarea-segmentation-method-based digital image correlation method

A technology of digital images and sub-regions, which is applied in measurement devices, instruments, optical devices, etc., to achieve the effect of simplifying the solution process and easy to solve

Inactive Publication Date: 2015-12-16
LIAONING TECHNICAL UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] In order to solve the problem that the existing digital image correlation method cannot calculate the deformation near the junction of the two deformation modes, the present invention provides a digital image correlation method based on the semi-subregion segmentation method, which can calculate the deformation that cannot be calculated by the traditional digital image correlation method. Measuring points in the following three cases: (1) Points located on the model boundary; (2) Nearby points containing two kinds of uniform deformation; (3) Points located near cracks

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Embodiment 1

[0065] This embodiment is the effect of the present invention including two kinds of uniformly deformed points near the calculation. respectively using the traditional sub-pixel digital image correlation method and the present invention to calculate Figure 5-a Variations from 8-1 to 8-2, wherein the side length of the sub-region is set to 31 pixels, the same below. The measuring point is selected at Figure 5-a On the horizontal straight line 9-1 in , the measuring point after deformation should be on the broken line 9-2. Figure 6-a is the displacement vector field calculated by the traditional digital image correlation method (hereinafter referred to as the traditional method), Figure 6-b is the displacement vector field calculated by the present invention. Figure 6-c The correlation coefficient calculated for the two methods, wherein, 10-1 is the result of the traditional method, and 10-2 is the result of the present invention. The correlation coefficient adopts a cr...

Embodiment 2

[0068] This embodiment is the effect of the present invention on calculating points located near cracks. Using the traditional digital image correlation method and the present invention to calculate Figure 5-b Variation of 8-3 to 8-4 in the middle. The measuring point is selected on the vertical straight line 9-3 in 8-3, and the deformed measuring point should be on the broken line 9-4. Figure 7-a , Figure 7-b , Figure 7-c , Figure 7-e , Figure 7-e They are respectively the displacement vector field calculated by the traditional method, the displacement vector field calculated by the present invention, the correlation coefficient calculated by the two methods, the horizontal displacement and the vertical displacement. Among them, 11-1, 11-3 and 11-6 are the results of the traditional method, 11-2, 11-4 and 11-7 are the results of the present invention, 11-5 and 11-8 are theoretical values.

[0069] It can be found that when the measuring point is selected far away ...

Embodiment 3

[0071] This embodiment is the effect of the present invention on calculating points located on the boundary of the model. First, the traditional digital image correlation method is used to calculate Figure 5-c Variation of the middle 8-5 to 8-6. The measuring point is selected on the horizontal straight line 9-5 close to the invalid area (hole) in 8-5, and the deformed measuring point should be on the straight line 9-6. The boundary of the invalid area is the boundary inside the model, and the measurement points near it are taken as the points on the boundary of the model. Figure 8-a , Figure 8-b , Figure 8-c , Figure 8-e , Figure 8-e They are respectively the displacement vector field calculated by the traditional method, the displacement vector field calculated by the present invention, the correlation coefficient calculated by the two methods, the horizontal displacement and the vertical displacement. Among them, 12-1, 12-3 and 12-6 are the results of the tradit...

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Abstract

Provided in the invention is a half-subarea-segmentation-method-based digital image correlation method. The correlation method comprises: a certain number of measurement points are distributed on a picture before deformation, a deformation field, containing two kinds of deformation modes, of a picture after deformation is obtained by using a sub-pixel digital image correlation method, and measuring points with poor results are selected; a square sample subarea is selected by using each measuring point with a poor result as a center, the subarea is segmented into two half subareas by using one line segment crossing the center point of the subarea, an optimum target subarea among all subareas at different segmentation angles is searched by using an overall-pixel digital image correlation method, and rough measurement displacement and a rough segmentation angle are obtained; and with the rough measurement displacement and rough segmentation angle as initial values, measurement displacement and a segmentation angle are searched precisely by using the sub-pixel digital image correlation method and a convex function extreme seeking method. Compared with the traditional digital image correlation method, the provided digital image correlation method enables displacement of measuring points near a boundary of two kinds of deformation modes to be searched and the application range is expanded.

Description

technical field [0001] The invention relates to a digital image correlation method suitable for deformation measurement near the junction of two deformation modes, in particular to a digital image correlation method based on a semi-subregion segmentation method. Background technique [0002] The digital image correlation method is an optical measurement method, which realizes the displacement and strain measurement of the object surface by correlating two speckle images of the object surface before and after deformation. This method has significant advantages: non-contact, high precision, full-field measurement and no special requirements for the measurement environment. At present, this method has become an advanced observation method in the fields of rock mechanics, material mechanics, and experimental mechanics. [0003] The digital image correlation method determines the displacement and strain of the point on the object according to the correlation of the speckle image...

Claims

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Application Information

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IPC IPC(8): G01B11/16G01B11/02
Inventor 杜亚志王学滨冯威武张楠
Owner LIAONING TECHNICAL UNIVERSITY
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