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 b

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

Example Embodiment

[0051] Example 1

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

[0053] (2) By spraying white / black 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 marker pen as the test point mark at the location to be tested, which is convenient for quickly finding the test location 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 the image before deformation is taken as a reference image, such as image 3 (b) Shown;

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

Example Embodiment

[0059] Example 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 paint on the surface of the sample, an artificial speckle pattern is prepared on the surface, such as Figure 4 (a) shown;

[0062] (3) Use a small black dot on the marker pen as the test point mark at the location to be tested, which is convenient for quickly finding the test location during the test;

[0063] (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 the image before deformation is taken as a reference image;

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

[0065] (6) Use the reference image and the target image processed by ...

Example Embodiment

[0066] Example 3

[0067] (1) Take the deformed sample in Example 2 as the sample to be tested and fix it on a flat surface;

[0068] (2) Use the black dot on the marker pen to mark the new measuring point at the position where drilling is needed;

[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 image clearly, and the image before the drilling is taken as a reference image, such as Figure 5 (a) shown;

[0070] (4) Raise the digital camera by adjusting the telescopic rod of the camera support rod or adjust the rotating button on the upper part of the camera support rod so that the digital camera and the support rod are in the same straight line, thereby leaving enough space for drilling;

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

[0072] (6) Restore the camera to its original position by...

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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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