CN105842062A - Real-time crack propagation monitoring device and real-time crack propagation monitoring method - Google Patents
Real-time crack propagation monitoring device and real-time crack propagation monitoring method Download PDFInfo
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- CN105842062A CN105842062A CN201610388143.3A CN201610388143A CN105842062A CN 105842062 A CN105842062 A CN 105842062A CN 201610388143 A CN201610388143 A CN 201610388143A CN 105842062 A CN105842062 A CN 105842062A
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Abstract
The invention provides a real-time crack propagation monitoring device and a real-time crack propagation monitoring method. The real-time crack propagation monitoring device comprises a loading device, a white light source, a fixed-focus telecentric lens, a CCD (charge coupled device) camera, a CCD camera adjustment support and a computer. A specimen is placed on the loading device, the fixed-focus telecentric lens is mounted at the front end of the CCD camera, the CCD camera is fixed to the CCD camera adjustment support and connected with the computer through a data cable, the white light source is fixed in front of and above the fixed-focus telecentric lens, and an image acquisition system and DIC (digital image correlation) software are installed on the computer. According to a digital image correlation method, correlation coefficients of two speckle images before and after crack propagation are calculated to determine crack propagation areas according to the correlation coefficients, high crack measurement precision is realized, microcracks difficult for manual visual recognition can be effectively recognized, and accuracy and reliability of test results are improved.
Description
Technical field
The invention belongs to crack monitoring technical field, be specifically related to a kind of Crack Extension real-time monitoring device for damage tolerance test and method.
Background technology
Along with the deep application in aeroplane structure design and evaluation of the damage tolerance technology, damage tolerance test technology more and more higher by attention degree.In the aircraft development stage, for obtaining material and the crack expansion characteristic of structure, generally require and carry out substantial amounts of damage tolerance test.In process of the test, while need to carrying test specimen being applied repeatability spectrum, monitoring and measuring propagation direction and the length of crackle, and the accurate of crack extending length measures the important prerequisite being to obtain the performance parameters such as crack propagation rate.
At present, damage tolerance test is many by scale or the means of prefabricated scale, uses the method for artificial range estimation that the Crack Extension situation of test specimen is carried out periodic monitoring.Although artificial visual method technical sophistication degree is low, be easily achieved, but the method subjectivity is big, precision and efficiency low, and be difficult to the real-time monitoring of Crack Extension.
Summary of the invention
To be solved by this invention is existing crackle monitoring device precision and inefficient technical problem, it is provided that a kind of Crack Extension real-time monitoring device based on loading by means of digital image correlation method (DIC) and method.
In order to solve the technical problem of the present invention, the present invention is achieved by the following technical solutions: a kind of Crack Extension real-time monitoring device, including charger 1, white light source 3, focus telecentric lens 4, CCD camera 5, CCD camera regulation support 6 and computer 7, test specimen 2 is laid on described charger 1, the described telecentric lens 4 that focuses is arranged on described CCD camera 5 front end, described CCD camera 5 is fixed on described CCD camera regulation support 6, and described CCD camera 5 is connected with computer 7 by data wire；Described white light source 3 focuses the front upper place of telecentric lens 4 described in being fixed on.Preferably, described computer 7 is provided with image capturing system relevant with digital picture (DIC) software.
The monitoring method of a kind of Crack Extension real-time monitoring device, comprises the following steps:
Step one: make chequered with black and white random speckle pattern on test specimen 2 surface.
Step 2: in testing ground, arranges crack monitoring system.
Step 3: open image capturing system, and debug, adjusts CCD camera 5 angle, it is ensured that focus telecentric lens 4 axis vertical with test specimen 2 surface；Adjust CCD camera 5 and test specimen 2 distance, it is ensured that test specimen 2 surface regional imaging to be measured is clear and image is in depth of field centre position；Adjust position and the brightness of white light source 3, it is ensured that test specimen 2 surface uniform light, light and shade are moderate.
Step 4: before on-test, uses CCD camera 5 shoot surface of test piece region to be measured speckle image and preserve to computer 7, and prestore in described computer 7 correlation coefficient threshold.
Step 5: in process of the test, by arranging the speckle image on periodically automatic shooting test specimen 2 surface, IMAQ interval and preserving to computer 7, need to guarantee during IMAQ that test specimen 2 is in extended state, i.e. crackle is in open configuration.
Step 6: use the speckle image of the shooting front with test of the speckle image of shooting in loading by means of digital image correlation method comparative analysis process of the test, searched for by whole pixel matching, calculate the standardization covariance coefficient correlation of region to be measured various location, filtering out the coefficient correlation region less than threshold value, this region is Crack Extension region.
Step 7: according to camera lens multiplication factor, CCD chip size and image resolution ratio, set up the proportionate relationship between pixel value and physical size, changes the physical size to test specimen 2 by the pixel dimension of crack extending length.
Preferably, the threshold value of described step 4 neutralization procedure six is 0.5 ~ 0.8, and threshold size suitably can adjust according to the quality of speckle image.
Compared with prior art, the present invention obtains and provides the benefit that:
A kind of Crack Extension real-time monitoring device disclosed by the invention and method, can realize crackle and monitor in real time, and crack length need not when measuring suspend testing equipment, improves test efficiency, saves test period；The coefficient correlation of two width speckle images before and after loading by means of digital image correlation method On Crack Propagation is utilized to calculate, the region that Crack Extension occurs is differentiated by the size of coefficient correlation, crackle certainty of measurement is high, the impalpable micro-crack of artificial range estimation be can effectively identify, accuracy and the reliability of result of the test improved.
A kind of Crack Extension real-time monitoring device disclosed by the invention and method, it is applicable to the measurement of crack extending length and propagation direction, belong to damage tolerance (Crack Extension) test category, it is not required to solve displacement field and strain field, reduce computation complexity, improving image processing speed, to meet the needs of monitoring in real time, the stool and urine according only to coefficient correlation can differentiate that crackle occurs position, measures crack extending length.
Accompanying drawing explanation
Fig. 1 is Crack Extension real-time monitoring device schematic diagram.
Reference: 1, charger；2, test specimen；3, white light source；4, telecentric lens is focused；5, CCD camera；6, CCD camera regulation support；7, computer.
Specific embodiments
Below in conjunction with the accompanying drawings, embodiment is described in detail.
See accompanying drawing 1, a kind of Crack Extension real-time monitoring device, including charger 1, white light source 3, focus telecentric lens 4, CCD camera 5, CCD camera regulation support 6 and computer 7, test specimen 2 is laid on described charger 1, the described telecentric lens 4 that focuses is arranged on described CCD camera 5 front end, described CCD camera 5 is fixed on described CCD camera regulation support 6, and described CCD camera 5 is connected with computer 7 by data wire；Described white light source 3 focuses the front upper place of telecentric lens 4 described in being fixed on；Described computer 7 is provided with image capturing system relevant with digital picture (DIC) software.
A kind of Crack Extension real-time monitoring device based on loading by means of digital image correlation method, it is characterized in utilizing the coefficient correlation of two width speckle images before and after loading by means of digital image correlation method On Crack Propagation to calculate, and then is differentiated the region (path) that Crack Extension occurs by the size of coefficient correlation.
It is side crops industry that the spectrum applied due to usual damage tolerance test carries relative to structural limits load, and most of region of test specimen belongs to small deformation category, and the coefficient correlation in this region is higher.And slit region exists bigger relative displacement, before and after Crack Extension, speckle image differs greatly, and coefficient correlation the most drastically declines.Therefore, use coefficient correlation based on DIC method to carry out monitoring crack extension and there is higher reliability and sensitivity.
The monitoring method of a kind of Crack Extension real-time monitoring device, comprises the following steps:
Step one: make chequered with black and white random speckle pattern on test specimen 2 surface.
Step 2: in testing ground, arranges crack monitoring system.
Step 3: open image capturing system, and debug, adjusts CCD camera 5 angle, it is ensured that focus telecentric lens 4 axis vertical with test specimen 2 surface；Adjust CCD camera 5 and test specimen 2 distance, it is ensured that test specimen 2 surface regional imaging to be measured is clear and image is in depth of field centre position；Adjust position and the brightness of white light source 3, it is ensured that test specimen 2 surface uniform light, light and shade are moderate.
Step 4: before on-test, uses CCD camera 5 shoot surface of test piece region to be measured speckle image and preserve to computer 7, and prestore in described computer 7 correlation coefficient threshold.
Step 5: in process of the test, by arranging the speckle image on periodically automatic shooting test specimen 2 surface, IMAQ interval and preserving to computer 7, need to guarantee during IMAQ that test specimen 2 is in extended state, i.e. crackle is in open configuration.
Step 6: use the speckle image of the shooting front with test of the speckle image of shooting in loading by means of digital image correlation method comparative analysis process of the test, searched for by whole pixel matching, calculate the standardization covariance coefficient correlation of region to be measured various location, filtering out the coefficient correlation region less than threshold value, this region is Crack Extension region.
Step 7: according to camera lens multiplication factor, CCD chip size and image resolution ratio, set up the proportionate relationship between pixel value and physical size, changes the physical size to test specimen 2 by the pixel dimension of crack extending length.
Further, the threshold value of described step 4 neutralization procedure six is 0.5 ~ 0.8, and threshold size suitably can adjust according to the quality of speckle image.
Can realize crackle by said apparatus and method to monitor in real time, crack length need not when measuring suspend testing equipment, improves test efficiency, saves test period；The coefficient correlation of two width speckle images before and after loading by means of digital image correlation method On Crack Propagation is utilized to calculate, the region that Crack Extension occurs is differentiated by the size of coefficient correlation, crackle certainty of measurement is high, the impalpable micro-crack of artificial range estimation be can effectively identify, accuracy and the reliability of result of the test improved.
A kind of Crack Extension real-time monitoring device and method, it is applicable to the measurement of crack extending length and propagation direction, belong to damage tolerance (Crack Extension) test category, it is not required to solve displacement field and strain field, reduce computation complexity, improving image processing speed, to meet the needs of monitoring in real time, the stool and urine according only to coefficient correlation can differentiate that crackle occurs position, measures crack extending length.
Listed above is only one of specific embodiment of the present invention.It is clear that the invention is not restricted to above example, it is also possible to there are many similar reshapings.All deformation that those of ordinary skill in the art can directly derive from present disclosure or associate, are all considered as invention which is intended to be protected.
Claims (3)
1. a Crack Extension real-time monitoring device, it is characterized in that: include charger (1), white light source (3), focus telecentric lens (4), CCD camera (5), CCD camera regulation support (6) and computer (7), test specimen (2) is laid on described charger (1), the described telecentric lens (4) that focuses is arranged on described CCD camera (5) front end, described CCD camera (5) is fixed in described CCD camera regulation support (6), and described CCD camera (5) is connected with computer (7) by data wire；Described white light source (3) focuses the front upper place of telecentric lens (4) described in being fixed on, and described computer (7) is provided with image capturing system and digital picture related software.
The monitoring method of a kind of Crack Extension real-time monitoring device the most as claimed in claim 1, it is characterised in that: comprise the following steps:
Step one: make chequered with black and white random speckle pattern on test specimen (2) surface；
Step 2: in testing ground, arranges crack monitoring system；
Step 3: open image capturing system, and debug, adjusts CCD camera (5) angle, it is ensured that focus telecentric lens (4) axis vertical with test specimen (2) surface；Adjust CCD camera (5) and test specimen (2) distance, it is ensured that test specimen (2) surface regional imaging to be measured is clear and image is in depth of field centre position；Adjust position and the brightness of white light source (3), it is ensured that test specimen (2) surface uniform light, light and shade are moderate；
Step 4: before on-test, uses CCD camera (5) shooting surface of test piece region to be measured speckle image and preserves to computer (7), and prestore in described computer (7) correlation coefficient threshold；
Step 5: in process of the test, periodically automatically snaps the speckle image on test specimen (2) surface by arranging IMAQ interval and preserves to computer (7), need to guarantee that test specimen (2) is in extended state during IMAQ；
Step 6: use the speckle image of the shooting front with test of the speckle image of shooting in loading by means of digital image correlation method comparative analysis process of the test, searched for by whole pixel matching, calculate the standardization covariance coefficient correlation of region to be measured various location, filtering out the coefficient correlation region less than threshold value, this region is Crack Extension region；
Step 7: according to camera lens multiplication factor, CCD chip size and image resolution ratio, set up the proportionate relationship between pixel value and physical size, changes the physical size to test specimen (2) by the pixel dimension of crack extending length.
The monitoring method of a kind of Crack Extension real-time monitoring device the most as claimed in claim 2, it is characterised in that: the threshold value of described step 4 neutralization procedure six is 0.5 ~ 0.8.
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Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107741368A (en) * | 2017-10-10 | 2018-02-27 | 湖南大学 | One kind is used for three-dimensional structure propagation of internal cracks test system |
| CN108320284A (en) * | 2018-02-06 | 2018-07-24 | 重庆交通大学 | To the detection method and device of concrete filled steel tube interface state |
| CN109060824A (en) * | 2018-08-10 | 2018-12-21 | 广东工业大学 | Strain-pulse based on DIC technology responds covariance damnification recognition method |
| CN109060819A (en) * | 2018-07-06 | 2018-12-21 | 中国飞机强度研究所 | Error correcting method in visual field in a kind of measurement of vibration component crackle |
| CN109269893A (en) * | 2018-11-20 | 2019-01-25 | 西南交通大学 | A kind of material stress corrosion test macro and its test method based on image recognition |
| CN109490263A (en) * | 2018-11-01 | 2019-03-19 | 河海大学 | A kind of crack propagation piece and its application method for the measurement of steel box-girder crackle |
| CN110108556A (en) * | 2019-04-16 | 2019-08-09 | 中国人民解放军陆军装甲兵学院 | A kind of method and system of prediction brittle coating cracking |
| CN110155369A (en) * | 2019-05-29 | 2019-08-23 | 中国民航大学 | A kind of aircraft skin face crack inspection method |
| CN110987765A (en) * | 2019-09-07 | 2020-04-10 | 西安科技大学 | Rock mass microscopic fracture testing method based on three-dimensional digital speckle |
| CN111595890A (en) * | 2019-09-23 | 2020-08-28 | 哈尔滨理工大学 | Real-time observation method for ceramic thermal shock cracks |
| CN113446932A (en) * | 2021-05-18 | 2021-09-28 | 西北工业大学 | Non-contact crack measuring method and system |
| CN113899746A (en) * | 2021-09-30 | 2022-01-07 | 江苏纹动测控科技有限公司 | DIC-based steel structure fatigue crack propagation form measuring method |
| CN114088515A (en) * | 2021-11-02 | 2022-02-25 | 国家高速列车青岛技术创新中心 | Monocular vision multi-view crack propagation monitoring device |
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- 2016-06-02 CN CN201610388143.3A patent/CN105842062A/en active Pending
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107741368A (en) * | 2017-10-10 | 2018-02-27 | 湖南大学 | One kind is used for three-dimensional structure propagation of internal cracks test system |
| CN108320284A (en) * | 2018-02-06 | 2018-07-24 | 重庆交通大学 | To the detection method and device of concrete filled steel tube interface state |
| CN109060819B (en) * | 2018-07-06 | 2021-03-30 | 中国飞机强度研究所 | Method for correcting errors in field of view in measurement of cracks of vibration component |
| CN109060819A (en) * | 2018-07-06 | 2018-12-21 | 中国飞机强度研究所 | Error correcting method in visual field in a kind of measurement of vibration component crackle |
| CN109060824A (en) * | 2018-08-10 | 2018-12-21 | 广东工业大学 | Strain-pulse based on DIC technology responds covariance damnification recognition method |
| CN109490263A (en) * | 2018-11-01 | 2019-03-19 | 河海大学 | A kind of crack propagation piece and its application method for the measurement of steel box-girder crackle |
| CN109269893A (en) * | 2018-11-20 | 2019-01-25 | 西南交通大学 | A kind of material stress corrosion test macro and its test method based on image recognition |
| CN110108556A (en) * | 2019-04-16 | 2019-08-09 | 中国人民解放军陆军装甲兵学院 | A kind of method and system of prediction brittle coating cracking |
| CN110155369A (en) * | 2019-05-29 | 2019-08-23 | 中国民航大学 | A kind of aircraft skin face crack inspection method |
| CN110155369B (en) * | 2019-05-29 | 2022-05-17 | 中国民航大学 | Method for checking surface cracks of aircraft skin |
| CN110987765A (en) * | 2019-09-07 | 2020-04-10 | 西安科技大学 | Rock mass microscopic fracture testing method based on three-dimensional digital speckle |
| CN110987765B (en) * | 2019-09-07 | 2022-10-11 | 西安科技大学 | Rock mass microscopic fracture testing method based on three-dimensional digital speckles |
| CN111595890A (en) * | 2019-09-23 | 2020-08-28 | 哈尔滨理工大学 | Real-time observation method for ceramic thermal shock cracks |
| CN113446932A (en) * | 2021-05-18 | 2021-09-28 | 西北工业大学 | Non-contact crack measuring method and system |
| CN113899746A (en) * | 2021-09-30 | 2022-01-07 | 江苏纹动测控科技有限公司 | DIC-based steel structure fatigue crack propagation form measuring method |
| CN114088515A (en) * | 2021-11-02 | 2022-02-25 | 国家高速列车青岛技术创新中心 | Monocular vision multi-view crack propagation monitoring device |
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Application publication date: 20160810 |