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Method and device of measuring dynamic crack lengths

A crack length and dynamic measurement technology, which is applied to measuring devices, using optical devices, and applying repetitive force/pulse force to test the strength of materials, etc. , to achieve the effect of reliable measurement results, time-saving installation and adjustment, and simple operation process

Inactive Publication Date: 2016-03-02
NORTHWESTERN POLYTECHNICAL UNIV
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Problems solved by technology

[0002] In the material fatigue crack growth test, the visual method is often used to measure the crack length. Generally, the test needs to be interrupted to read the crack length, and the crack length is inconvenient to observe, and the possibility of error is high; the flexibility method can also be used to measure the crack length, and the clip-type extension is often used. The gauge detects the opening displacement of the crack, and it is in direct contact with the test piece when it is used. The misalignment of the holding position and the vibration of the test piece will affect the calibration accuracy; the non-contact video extensometer produced according to the image processing technology can be realized in the The crack opening displacement information is collected without contact with the specimen, but there is a shortage of real-time collection of dynamic crack opening displacement data

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  • Method and device of measuring dynamic crack lengths
  • Method and device of measuring dynamic crack lengths

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Embodiment Construction

[0034] Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

[0035] Connect the digital image acquisition system with a computer equipped with a data processing program to form a non-contact crack length measurement and analysis system. The digital image acquisition system quickly collects and recognizes the real-time graphic information of the continuously loaded test piece and transmits it to the computer. The program data is processed to obtain the dynamic crack length of the test piece, and the measurement steps are as follows: 1) Install the test piece with the mark on the loading test machine, adjust the light source and the fixed adjustment device installed with the digital image acquisition system, so that the digital image acquisition system can capture to the logo image; 2) image calibration, collecting images under static load conditions, and determining the ratio L of the actual distance per unit pixel to the di...

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Abstract

The invention relates to a method and device of measuring dynamic crack lengths, comprising: loading a cracked test piece; employing a non-contact crack measurement analysis system to collect opening displacement data of a crack port; utilizing sine curve fitting to obtain a greatest value of opening displacement; and utilizing the relation between crack port opening displacement and a crack length to obtain the crack length under corresponding circulation. According to test verification, the method is more convenient and faster than a traditional method, and can obtain real and reliable results.

Description

technical field [0001] The invention belongs to the research fields of light side mechanics, engineering materials and fatigue fracture mechanics, and in particular relates to a dynamic measurement method and device for crack length. Background technique [0002] In the material fatigue crack growth test, the visual method is often used to measure the crack length. Generally, the test needs to be interrupted to read the crack length, and the crack length is inconvenient to observe, and the possibility of error is high; the flexibility method can also be used to measure the crack length, and the clip-type extension is often used. The gauge detects the opening displacement of the crack, and it is in direct contact with the test piece when it is used. The misalignment of the holding position and the vibration of the test piece will affect the calibration accuracy; the non-contact video extensometer produced according to the image processing technology can be realized in the The...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/02G01N3/32
Inventor 殷之平陈建军刘嘉鹏丁国元
Owner NORTHWESTERN POLYTECHNICAL UNIV
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