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Stress test system based on digital image correlation method and application thereof

A stress testing and digital image technology, applied in the field of stress testing system based on digital image correlation method, can solve problems such as difficulty in realizing large/small-scale testing, flexible testing of full-field/local testing, complicated testing steps, and complicated data processing, etc. , to avoid the limitation of measurement stress, low test cost and high measurement accuracy

Inactive Publication Date: 2015-11-11
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The invention is based on laser speckle technology, the test device is complex, and the sample surface has high requirements in order to realize speckle interference; the test steps are complicated, and speckle fields in two directions need to be collected before deformation, and after deformation, it needs to be tested in different laser beams. Speckle fields in two directions are collected under illumination; data processing is complex, and four speckle fields need to be calculated to obtain displacement information; it is difficult to realize flexible testing of large / small scale testing and full-field / local testing

Method used

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  • Stress test system based on digital image correlation method and application thereof
  • Stress test system based on digital image correlation method and application thereof
  • Stress test system based on digital image correlation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] (1) The material of the tested sample is marine 945 steel, the tested sample is polished, and the surface of the sample is wiped clean with alcohol;

[0053] (2) By spraying white / black spray paint on the surface of the sample, an artificial speckle pattern is prepared on the surface, such as image 3 As shown in (a), the gauge length of the stretched part is 80mm, the width is 10mm, and the thickness is 2mm.;

[0054] (3) Use a small black dot on the position to be tested as a mark of the test point, so that it is convenient to quickly find the test position during the test;

[0055] (4) Adjust the position and orientation of the test system according to the mark of the measuring point, so that the digital camera can image clearly, and take the image before deformation as a reference image, such as image 3 as shown in (b);

[0056] (5) Apply a tensile load of 1kN to the tested sample, and take the deformed image as the target image in this stretched state, such as ...

Embodiment 2

[0060] (1) The material of the tested sample is T23 steel, the tested sample is polished, and the surface of the sample is wiped clean with alcohol;

[0061] (2) By spraying white / black spray paint on the surface of the sample, an artificial speckle pattern is prepared on the surface, such as Figure 4 as shown in (a);

[0062] (3) Use a small black dot on the position to be tested as a mark of the test point, so that it is convenient to quickly find the test position during the test;

[0063] (4) Adjust the position and orientation of the test system according to the measuring point marks, so that the digital camera can clearly image, and take the image before deformation as a reference image;

[0064] (5) Apply a compressive load of 20kN to the tested sample, and then release the load. The sample after deformation is as follows: Figure 4 As shown in (b), take the deformed image as the target image;

[0065] (6) Using the digital image correlation method to process the ob...

Embodiment 3

[0067] (1) with the sample after deformation in embodiment 2 as tested sample, it is fixed on the flat plane;

[0068] (2) Use a black dot on the point where the hole needs to be drilled as a new measuring point mark;

[0069] (3) Adjust the position and orientation of the test system according to the mark of the measuring point, so that the digital camera can clearly image, and take the image before drilling as a reference image, such as Figure 5 as shown in (a);

[0070] (4) Raise the digital camera by adjusting the telescopic rod of the camera support rod or adjust the rotation knob on the upper part of the camera support rod to make the digital camera and the support rod in the same line, thereby leaving enough space for drilling;

[0071] (5) According to the test requirements, use a drilling machine to drill a hole with a certain aperture and depth at the mark of the measuring point;

[0072] (6) Return the camera to its original position by adjusting the telescopic r...

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Abstract

The invention relates to a stress test system based on a digital image correlation method and application thereof. The stress test system mainly comprises a digital camera, an imaging lens, a monochrome LED lighting source, a displacement platform, a camera support rod, a levelling instrument and a computer used for collection and analysis of a digital image, and the test process mainly comprises six steps. The test system has the characteristics of simple constitution, stable lighting source, easily adjustable height and direction of the digital camera, and the like. The specklegrams before and after drilling can be subjected to digital image correlation calculation, so that the test result can be obtained. The stress test system has the advantages of simplicity in operation, low test cost, high precision and the like. In the test process, a strain gage is not used, and the limitation that the strain gage is used for measuring the residual stress can be avoided. The system provided by the invention can be used for large / small scale test and overall / local test.

Description

technical field [0001] The invention belongs to the field of photomechanical performance, and relates to residual stress testing technology, in particular to a stress testing system based on a digital image correlation method and its application. Background technique [0002] In the field of engineering applications, the problem of residual stress has always attracted people's attention. Residual stress refers to the self-equilibrium internal stress that remains in the component due to the action and influence of various processes and other factors during the manufacturing process of the component when these factors disappear. Welding, casting, forging and other mechanical processing, surface treatment and other strengthening processes can cause residual stress, and the uneven plastic deformation caused by external force and temperature change is the main cause of residual stress. Residual stress not only reduces the bearing capacity of the structure and affects the dimensi...

Claims

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Application Information

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IPC IPC(8): G01N21/84
Inventor 徐济进林烈雄陆皓余春陈俊梅
Owner SHANGHAI JIAO TONG UNIV
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