CN114518289A - Control method for deformation strain control by video acquisition - Google Patents
Control method for deformation strain control by video acquisition Download PDFInfo
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- CN114518289A CN114518289A CN202210087504.6A CN202210087504A CN114518289A CN 114518289 A CN114518289 A CN 114518289A CN 202210087504 A CN202210087504 A CN 202210087504A CN 114518289 A CN114518289 A CN 114518289A
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000012360 testing method Methods 0.000 claims abstract description 38
- 239000000463 material Substances 0.000 claims abstract description 15
- 238000004422 calculation algorithm Methods 0.000 claims abstract description 5
- 230000000007 visual effect Effects 0.000 claims abstract description 5
- 238000004364 calculation method Methods 0.000 claims abstract description 4
- 238000012545 processing Methods 0.000 claims description 4
- 238000004458 analytical method Methods 0.000 claims description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
The application discloses a control method for deformation strain control by using video acquisition, which comprises the following steps: step 1, selecting a material sample to be tested, clamping the sample on a mechanical testing machine, and moving a video camera to a testing position. Step 2, marking points are freely set on the sample in the video visual field range through software to serve as strain control original gauge length; and 3, continuously acquiring images of sample deformation by a camera in test operation. And 4, calculating the original image obtained in the step 3 according to the set original scale distance by using a correlation algorithm to obtain a test deformation value. And 5, performing strain control on the electronic testing machine according to the deformation value obtained by video acquisition and calculation. The method can be applied to a plurality of scenes when strain control is inconvenient to use by using a mechanical extensometer.
Description
Technical Field
The application relates to the field of engineering material testing, in particular to a control method for deformation strain control by using video acquisition.
Background
The extensometer is an instrument for measuring the deformation of a test piece by a matching tester, and has a plurality of classifications, wherein an electronic extensometer is commonly used.
The electronic extensometer is a sensor for measuring the stress deformation of a test piece, generally utilizes the principle of electric signals, converts a strain gauge into resistance variation through the change of an elastic element, and finally converts and amplifies the resistance variation into a voltage signal. Strain gage extensometers are one type that is widely used.
With the development of modern technology, the variety and application range of engineering materials are greatly increased, and the deformation of a sample measured by using a traditional contact extensometer is limited in the following situations: 1. the soft sample cannot use a contact electronic extensometer; 2. mechanical contact is greatly influenced by manual operation, so that the precision of a measurement result is influenced; 3. the test installation process is complicated, and the test efficiency is low; 4. the adjustability of the gauge length is poor, the gauge length can be adjusted only in a few fixed gauge lengths, the operation of adjusting the gauge length is very troublesome, the influence on the measurement result is large, and when the specification of a sample is more, a plurality of extensometers are often needed; 5. the adaptability of a contact type electronic extensometer to temperature alternation is poor, the coverage of applicable high and low temperature ranges is small, and the high temperature and the low temperature are difficult to solve by using one extensometer; 6. the indexes such as Poisson's ratio and the like which need to be measured longitudinally and transversely at the same time can not be solved by using a contact type electronic extensometer at high and low temperatures, and the indexes in different domains or sections can not be measured at the same time; 7. in view of the limitation of measuring range and the protection requirement of the extensometer, the whole-course strain control test is basically impossible; 8. the influence of the test temperature on the extensometer is also large, and particularly in long-time high-low temperature load retention, endurance and creep test, the problem of the contact type electronic extensometer can not be solved basically. 9. The test process is not traceable, and the process of changing the sample cannot be reproduced.
Disclosure of Invention
In order to overcome the problems in the related art, the application provides a control method for deformation strain control by using video acquisition, which can overcome the defects of the deformation of a test piece measured by an electronic extensometer.
In order to solve the technical problem, the technical scheme adopted by the application is as follows:
a control method for deformation strain control by video acquisition is provided, which comprises the following steps:
step 1, selecting a material sample to be tested, clamping the sample on a mechanical testing machine, and moving a video camera to a testing position;
step 2, marking points are freely set on the sample in the video visual field range through software to serve as strain control original gauge length;
step 3, continuously collecting images of sample deformation by a camera in test operation;
step 4, calculating the original image obtained in the step 3 according to a set original scale distance by using a correlation algorithm to obtain a test deformation value;
and 5, performing strain control on the electronic testing machine according to the deformation value obtained by video acquisition and calculation.
Preferably, in step 1, a standard calibration card is used to calibrate the scale distance and obtain a clear image.
Preferably, in step 2, the distance between the marking points is a gauge length and can be set autonomously. (ii) a
Preferably, in step 3, an image of the material sample to be tested is acquired by the CCD camera, and if the brightness is insufficient, the material sample to be tested needs to be illuminated by an external light source.
Preferably, in step 4, the CCD camera collects original images at different time points, digital images collected at different times are stored in the computer by the image collection card, and the deformation size of the sample is calculated by comparing the position change of the selected sample mark in the previous and subsequent images by using the image processing technique.
Preferably, in step 5, the deformation result acquired and calculated by the video extensometer is transmitted to the integrated control and analysis system through a high-speed network interface, the deformation display and curve updating are carried out in real time, and the deformation value is transmitted back to the controller in real time through the controller and a WLAN interface of a computer, so that the strain pid control is realized.
The technical scheme provided by the application can comprise the following beneficial effects: a control method for deformation strain control by video acquisition is provided, which comprises the following steps: step 1, selecting a material sample to be tested, clamping the sample on a mechanical testing machine, and moving a video camera to a testing position; step 2, marking points are freely set on the sample in the video visual field range through software to serve as strain control original gauge length; step 3, continuously collecting images of sample deformation by a camera in test operation; step 4, calculating the original image obtained in the step 3 according to a set original scale distance by using a correlation algorithm to obtain a test deformation value; and 5, performing strain control on the electronic testing machine according to the deformation value acquired and calculated by the video. The method can be applied to a plurality of scenes when strain control is inconvenient to use by using a mechanical extensometer.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
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The foregoing and other objects, features and advantages of the application will be apparent from the following more particular descriptions of exemplary embodiments of the application, as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the application.
Fig. 1 is a schematic flowchart of a control method shown in embodiment 1 of the present application.
Fig. 2 is a system connection block diagram of the control method shown in embodiment 1 of the present application.
Detailed Description
Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application and should not be construed as limiting the present application.
In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral connections; can be mechanically or electrically connected; either directly or indirectly through intervening media, or through the communication between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise contact of the first and second features not directly but through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
The present application will be described in further detail below with reference to the accompanying drawings by way of specific embodiments.
Example 1
The video extensometer is a non-contact displacement sensor developed based on the modern digital image technology, and can meet the deformation tests of the above six occasions and can also be applied to the deformation test of common solid materials. Compared with the traditional knife edge extensometer, the automatic measuring device also has the advantages of automatically judging the necking position, randomly setting the gauge length and the measuring range, not wearing a test piece and the like. The developed testing principle of the video extensometer is that the stress-strain curve, the elastic modulus and other mechanical indexes of the material are tested by utilizing the modern digital image processing technology according to the characteristic that the mark is not deformed, and the precision can reach the magnitude of mum.
Referring to fig. 1 to 2, a method for controlling deformation strain by video capture includes:
step 1, selecting a material sample to be tested, clamping the sample on a mechanical testing machine, and moving a video camera to a testing position;
step 2, marking points are freely set on the sample in the video visual field range through software to serve as strain control original gauge length;
step 3, continuously collecting images of sample deformation by a camera in test operation; .
Step 4, calculating the original image obtained in the step 3 according to a set original scale distance by using a correlation algorithm to obtain a test deformation value;
and 5, performing strain control on the electronic testing machine according to the deformation value obtained by video acquisition and calculation.
Specifically, in step 1, a standard calibration card is used to calibrate the scale distance, and a clear image is obtained.
Specifically, in step 2, the distance between the marking points is a gauge length and can be set autonomously.
Specifically, in step 3, an image of the material sample to be tested is acquired through the CCD, and if the brightness is insufficient, the material sample to be tested needs to be illuminated by an external light source.
Specifically, in step 4, the CCD collects original images at different time points, digital images collected at different times are stored in the computer by the image collection card, and the deformation of the sample is calculated by comparing the position change of the selected sample mark in the previous and subsequent images by using the image processing technique.
Specifically, in step 5, the deformation result acquired and calculated by the video extensometer is transmitted to the integrated control and analysis system through the high-speed network interface, the deformation display and curve updating are carried out in real time, and the deformation value is transmitted back to the controller through the WLAN interface of the controller and the computer, so that the strain pid control is realized.
In the description herein, reference to the description of the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is a more detailed description of the present application in connection with specific embodiments thereof, and it is not intended that the present application be limited to the specific embodiments thereof. It will be apparent to those skilled in the art from this disclosure that many more simple derivations or substitutions can be made without departing from the spirit of the disclosure.
Claims (6)
1. A control method for deformation strain control by video acquisition is characterized by comprising the following steps:
step 1, selecting a material sample to be tested, clamping the sample on a mechanical testing machine, and moving a video camera to a testing position;
step 2, marking points are freely set on the sample in the video visual field range through software to serve as strain control original gauge length;
step 3, continuously collecting images of sample deformation by a camera in test operation;
step 4, calculating the original image obtained in the step 3 according to a set original scale distance by using a correlation algorithm to obtain a test deformation value;
and 5, performing strain control on the electronic testing machine according to the deformation value obtained by video acquisition and calculation.
2. The method for controlling deformation strain control by video capture according to claim 1, wherein in step 1, a standard calibration card is used to calibrate the gauge length and obtain a clear image.
3. The method for controlling deformation strain through video acquisition as claimed in claim 1, wherein in step 2, the distance between the marking points is a gauge length and can be set autonomously.
4. The method for controlling deformation strain through video acquisition as claimed in claim 1 or 3, wherein in step 3, the image of the material sample to be tested is acquired through the camera, and if the brightness is insufficient, the material sample to be tested needs to be illuminated by an external light source.
5. The method according to claim 1, wherein in step 4, the camera captures original images at different time points, digital images captured at different times are stored in the computer by an image capture card, and the deformation of the sample is calculated by comparing the position change of the selected sample mark in the images before and after the image processing technique.
6. The method as claimed in claim 1, wherein in step 5, the deformation result collected and calculated by the video extensometer is transmitted to the integrated control and analysis system through a high-speed network interface, the deformation display and curve update are performed in real time, and the deformation value is transmitted back to the controller through the WLAN interface of the controller and the computer in real time, so as to realize the pid control of the strain.
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| CN202210087504.6A CN114518289A (en) | 2022-01-25 | 2022-01-25 | Control method for deformation strain control by video acquisition |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117091953A (en) * | 2023-10-19 | 2023-11-21 | 深圳市海塞姆科技有限公司 | Automatic measuring method, computer equipment, system and storage medium for sample deformation |
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