CN210665329U - Non-contact crack opening displacement measuring device for bending fracture test - Google Patents
Non-contact crack opening displacement measuring device for bending fracture test Download PDFInfo
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- CN210665329U CN210665329U CN201920837549.4U CN201920837549U CN210665329U CN 210665329 U CN210665329 U CN 210665329U CN 201920837549 U CN201920837549 U CN 201920837549U CN 210665329 U CN210665329 U CN 210665329U
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- 238000012360 testing method Methods 0.000 title claims abstract description 64
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- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 5
- 229910052721 tungsten Inorganic materials 0.000 claims description 5
- 239000010937 tungsten Substances 0.000 claims description 5
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- 238000012634 optical imaging Methods 0.000 abstract description 3
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- 230000007613 environmental effect Effects 0.000 description 2
- 238000007656 fracture toughness test Methods 0.000 description 2
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Abstract
本实用新型属于材料性能测试领域，特别是一种弯曲断裂测试的非接触式裂纹张开位移测量装置。包括力学实验机；弯曲测试工装：包括一个上压头和两个下压头，试样装夹在上压头和下压头之间；数字图像采集系统：包括工业相机，成像镜头，设置在成像镜头前端的环形LED照明光源，相机支撑系统和反射镜；反射镜呈45°倾斜角设置在试样的下部，反射镜将光源产生的光线反射至试样断裂表面，同时将断裂试样表面图像反射入成像镜头内；控制系统：实时显示工业相机图像，计算实时裂纹张开位移。本实用新型使用光学成像系统采集试样裂纹口周围的图像，利用数字图像相关算法计算实时裂纹张开位移，可以实现非接触式测量，测量装置对样品不产生任何影响。
The utility model belongs to the field of material performance testing, in particular to a non-contact crack opening displacement measuring device for bending fracture testing. Including mechanical experiment machine; bending test tool: including one upper indenter and two lower indenters, the sample is clamped between the upper indenter and the lower indenter; digital image acquisition system: including industrial camera, imaging lens, set in The ring-shaped LED illumination light source at the front of the imaging lens, the camera support system and the reflector; the reflector is arranged at the lower part of the sample at a 45° inclination angle, and the reflector reflects the light generated by the light source to the fracture surface of the sample, and at the same time, the surface of the fractured sample is reflected by the reflector. The image is reflected into the imaging lens; the control system: displays the industrial camera image in real time, and calculates the real-time crack opening displacement. The utility model uses an optical imaging system to collect images around the crack opening of the sample, uses a digital image correlation algorithm to calculate the real-time crack opening displacement, can realize non-contact measurement, and the measurement device does not have any influence on the sample.
Description
Technical Field
The utility model belongs to material performance test field, especially a displacement measurement device is opened to non-contact crackle of bending fracture test.
Background
The single-side notch sample bending fracture test, such as three-point bending or four-point bending, is a common method for evaluating the fracture toughness of materials. For brittle materials, when a sample meets the mechanical conditions of linear elastic fracture, the three-point bending test is generally referred to the national standard GB/T4161-2007 or the American ASTM E399-17 standard, and the critical stress intensity factor KIC of material fracture is directly obtained. For the tough material, the critical J integral or the critical crack tip opening displacement based on the elastoplastic fracture mechanics is adopted by generally referring to the national standard GB/T21143-2014 or the American ASTM E1820-15 standard.
No matter the linear elastic or elastic-plastic fracture mechanics testing method is selected, the key of the bending fracture testing is to accurately measure the Crack Opening Displacement (CMOD) of the sample. The conventional CMOD measurement widely adopts a resistance strain gauge clip type extensometer which is in direct contact with a sample, and the extensometer is directly arranged in a crack opening of the sample through a blade, so that the opening displacement of the crack opening can be measured in real time. However, clip-on extensometers suffer from a number of deficiencies: (1) the gauge length is fixed, the measuring range is limited, and the expansion displacement in a larger range is difficult to measure; (2) directly contacting the sample and exerting a large reaction force on the sample, not using a material that is particularly brittle or particularly soft; (3) before and after the test of the sample, the extensometer needs to be installed and removed, and the operation is complex; (4) when the material is suddenly broken, the extensometer is easy to drop and be mechanically damaged; (5) and the limited applicable temperature range cannot be compatible with high-temperature test at the same time.
In addition, it is difficult to obtain a standard size fracture specimen due to limitations of material preparation methods, service environments, workpiece shapes (e.g., pipes, thin walls, etc.), and the like. In these cases, it is important to conduct a small-size bending fracture test. However, the clip-on extensometer is generally bulky, and the minimum crack opening capable of measurement is also wide (for example, the minimum crack opening width of the clip-on extensometer of Epsilon 3541 model is 2.5mm), so that the test requirements of the micro-sample are difficult to meet.
In addition to conventional environmental testing, fracture performance evaluation in extreme environments is sometimes required to ensure that the material is sufficiently safe in service. When bending fracture toughness tests are carried out under high-temperature or low-temperature conditions, corresponding high-temperature or low-temperature clamp type extensometers are generally adopted, and holes are required to be formed in an environment box or the opening displacement of a crack opening of a sample in the box is converted to the outside of the box through an extension rod and other devices. This necessarily results in complicated environmental chamber designs, increasing insulation difficulties and low temperature dielectric losses, while possibly introducing test errors. When fracture tests are carried out in different temperature environments (high temperature, room temperature and low temperature), corresponding extensometers need to be replaced, so that the test process becomes complicated, and the acquisition cost of equipment is increased. In addition, if the fracture test is to be performed in a corrosive medium environment, the test conditions are more complicated and the corrosive medium may damage the extensometer.
SUMMERY OF THE UTILITY MODEL
The utility model provides a technical problem lie in providing a displacement measurement device and method are opened to non-contact crackle of bending fracture test.
Realize the utility model discloses the technical solution of purpose does:
a non-contact crack opening displacement measuring device for bending fracture test comprises
A mechanical experiment machine;
bending test tooling: the bending test tool is loaded in a mechanical experiment machine, the bending test tool comprises an upper pressure head and two lower pressure heads, a sample is clamped between the upper pressure head and the lower pressure heads, the upper pressure head is arranged in the middle of the sample, and the two lower pressure heads are respectively arranged at two ends of the sample;
a digital image acquisition system: the system comprises an industrial camera, an imaging lens arranged at the front end of the industrial camera, an annular LED illuminating light source arranged at the front end of the imaging lens, a camera supporting system and a reflector; the reflector is arranged below the sample at an inclination angle of 45 degrees, reflects light rays generated by the annular LED illumination light source to the fracture surface of the sample, and reflects the surface image of the fracture sample into the imaging lens;
the control system comprises: the industrial camera and the mechanical experiment machine are connected with the control system, the control system displays the image of the industrial camera in real time, calculates the opening displacement of the real-time crack, and synchronously acquires a load signal output by the mechanical experiment machine or feeds back the opening displacement of the crack obtained by calculation to the mechanical experiment machine.
Further, the mechanical experiment machine comprises an upper chuck, a lower chuck, a cross beam, a vertical frame and a base; the lower chuck is fixedly arranged on the base, the upper chuck is arranged on the lower side of the middle part of the cross beam, and the cross beam is movably arranged on the vertical frame.
Furthermore, the bending test tool further comprises an upper connecting rod, a bending tool base and a lower connecting rod;
and one end of the lower connecting rod is connected with the bending tool base, and the other end of the lower connecting rod is connected with the lower chuck.
Furthermore, a sliding groove is formed in the upper surface of the bending tool base, the lower pressing head is fixedly installed on the bending tool base through the sliding groove, and the reflector is fixedly installed on the bending tool base through the reflector base;
the side face of the bending tool base is provided with span scales, and the positions of the lower pressure head and the reflector base in the sliding groove are arranged according to the span scales.
Further, the top ends of the upper pressure head and the lower pressure head are provided with tungsten steel bars, and the upper pressure head and the lower pressure head are in line contact with the sample through the tungsten steel bars;
and the upper surface of the lower pressure head is provided with centering scales for centering the sample.
Further, the camera support system comprises a fixed block, a three-dimensional translation table, a connecting plate, a profile beam and a tripod;
the industrial camera is fixed at the tail of the imaging lens through C-port threads, the imaging lens is fixed on the three-dimensional translation table through a fixing block, the three-dimensional translation table is fixed on the profile cross beam through a connecting plate, and the profile cross beam is fixed on a tripod;
by adjusting the height, the direction and the position of the tripod, the imaging lens is aligned to be perpendicular to the sample, and the working distance of the sample on the lens is ensured.
Further, the reflector is fixed at the central position of a chute of the bending tool base through a 45-degree inclined reflector base and is opposite to the sample prefabricated notch; the reflector is an optical lens with reflectivity higher than 98%.
Further, the imaging lens is a low-distortion telecentric optical lens and is a fixed-focus or fixed-magnification zoom lens, and the magnification is selected according to the size of the detected sample;
the industrial camera is a CCD or CMOS camera, and the resolution is selected according to the measurement precision requirement;
the annular LED illuminating light source is used for generating uniform shadowless light, and the illumination intensity of the annular LED illuminating light source is adjusted according to a use scene.
Furthermore, the control system is a computer, and measurement control software is arranged in the computer.
A method for measuring by using the device comprises the following steps:
the method comprises the following steps: drawing white background on two sides of the notch of the sample, and spraying black spots to form random measuring speckles;
step two: adjusting the span of the two lower pressure heads, and placing the sample on the lower pressure heads with the gap facing downwards; adjusting a tripod to enable the height of an imaging lens to be consistent with that of a reflector, wherein the imaging lens is opposite to a sample plane, observing a sample speckle image in real time through a control system, adjusting the position of the imaging lens and focusing the image by using a three-dimensional translation table, and adjusting the intensity of an annular LED (light-emitting diode) illumination light source to enable the collected speckle image to be clear and moderate in contrast;
step three: capturing a speckle image through measurement control software to serve as an initial reference image, selecting 1 group of pixel subsets on two sides of a crack respectively to serve as feature points, adjusting the size of each group of 5-8 points, and enabling the feature points to be suitable for digital image correlation analysis;
step four: starting measurement control software, entering a real-time analysis mode, observing the fluctuation condition of displacement data when the displacement data are not loaded, and reselecting a mark point or spraying a speckle pattern again if the data fluctuation is overlarge;
step five: starting a dynamics experiment machine test program, and starting loading;
step six: in the testing process, the measurement control software collects speckle images in real time, digital image correlation analysis is completed in a memory, the relative displacement of the selected characteristic points of the speckle images relative to a reference image is calculated, the crack opening displacement is calculated, the measurement control software can synchronously collect load signals output by a mechanical experiment machine and draw a load-displacement curve in real time, and the measurement control software can also feed back the calculated crack opening displacement signals to the mechanical experiment machine;
step seven: and after the test is finished, stopping measuring the real-time analysis mode of the control software.
Compared with the prior art, the utility model, it is showing the advantage as follows:
(1) the utility model discloses use optical imaging system to gather the image around the sample crackle mouth, utilize the relevant algorithm of digital image to calculate real-time crackle and open the displacement, can realize non-contact measurement, measuring device does not produce any influence to the sample. The digital image correlation algorithm calculates the sub-pixel displacement of all the mark points by using a nonlinear optimization method, so that the calculation and measurement precision is superior to 0.01 pixel, and the fracture toughness measurement of the miniature three-point bending sample is realized.
(2) Through the high transparent observation window of low temperature, high temperature environment case or liquid medium container design, the utility model discloses can conveniently realize special environment's bending fracture test.
(3) The utility model discloses use in a flexible way, the bending test anchor clamps are adjustable down the pressure head span, and the speculum base, microscope head and CCD industry camera all can be changed as required to adapt to not unidimensional sample and test environment.
(4) The utility model discloses a displacement measurement range broad is opened to the crackle, can be used for the test of line elasticity brittle material and elastoplasticity toughness material simultaneously.
Drawings
FIG. 1 is a schematic structural diagram of a testing apparatus according to the present application.
FIG. 2 is a schematic perspective view of a reflector and a front surface of a bending test fixture according to the present application.
FIG. 3 is a schematic perspective view of a reflector and a side of a bending test fixture according to the present application.
FIG. 4 is a schematic diagram of the present application of a mirror for viewing the marked area of a sample.
FIG. 5 random speckle marking area images and selected feature points of the present application.
FIG. 6 is a graph of the relationship between the opening displacement and the load of a tungsten alloy crack opening in an embodiment of the present application.
Description of reference numerals:
the method comprises the following steps of 1-a mechanical experiment machine, 2-a sample, 3-a bending test tool, 4-an annular LED lighting source, 5-an imaging lens, 6-an industrial camera, 7-a fixed block, 8-a three-dimensional translation table, 9-a connecting plate, 10-a beam, 11-a tripod, 12-a data line, 13-a control system, 14-an upper connecting rod, 15-an upper pressure head, 16-a lower pressure head, 17-a centering scale, 18-a bending tool base, 19-a span scale, 20-a lower connecting rod, 21-a sliding block, 22-a reflector base, 23-a reflector and 24-a characteristic point.
Detailed Description
In order to describe the technical solution and the testing method of the present invention more clearly and intuitively, the following description will be further made with reference to the accompanying drawings.
As shown in fig. 1 and 2, the utility model provides a displacement measurement device is opened to bending fracture test's non-contact crackle, including speculum 23, imaging lens 5, industrial camera 6, annular LED illuminating light source 4, calibration plate, three-dimensional translation platform 8, the braced system who comprises section bar crossbeam 10 and tripod 11 and be used for control and real-time digital image acquisition's control system 13.
The position relation is as follows: the industrial camera 6 is fixed at the tail part of the imaging lens 5 through standard C-port threads; the imaging lens 5 is fixed on a three-dimensional translation table 8 through a fixing block 7; the three-dimensional translation table 8 is fixed on a section bar beam 10 through a connecting plate 9; the beam is fixed to a tripod 11. By adjusting the height, orientation and position of the tripod 11, it is ensured that the imaging lens 5 is aligned and perpendicular to the sample 2, while ensuring that the sample 2 is near the working distance of the lens. The industrial camera 6 is connected to a control system 13 via a data line 12.
As shown in fig. 2 and 3, in the three-point bending test fixture 3, knurling is formed on the surface of one end of each of the upper connecting rod 14 and the lower connecting rod 20, so that the clamping head of the mechanical testing machine 1 can be conveniently clamped; the other end is a threaded rod which is respectively screwed into the threaded holes of the upper pressure head 15 and the bending tool base 18. The upper indenter 15 and the lower indenter 16 of the bend test fixture both contact the test specimen 2 through a tungsten steel rod at their top ends. The bending tool base 18 is provided with a slide rail, the slide rail can enable the reflector base 22 and the 2 lower press heads 16 to be installed on the base, and the screws for locking the lower press heads 16 and the slide block 21 can fix the lower press heads on the slide rail. In addition, the upper end of the lower pressure head is provided with a centering scale 17 for accurate and rapid centering of the sample. The side of the base is provided with span scales 19, which is convenient for adjusting the span between the 2 lower press heads 15 so as to adapt to samples with different sizes.
As shown in fig. 4, the reflecting mirror 23 is fixed at the central position of the slide rail of the bending tool base 18 through a 45 ° tilting base 22, and faces the sample pre-cut. The reflector 23 is an optical lens with a reflectivity higher than 98%, and is configured to reflect light generated by the annular LED illumination light source 4 to a surface of a broken sample, and reflect an image of the surface of the broken sample into the imaging lens 5. Through the design, the optical imaging system can effectively measure the crack opening displacement of the lower surface of the bending fracture sample.
The imaging lens 5 is a low-distortion telecentric optical lens, can be fixed-focus or fixed-magnification zooming, and the magnification of the imaging lens can be selected according to the size of a detected sample.
The industrial camera 6 is a CCD or CMOS camera, and the resolution can be selected according to the measurement precision requirement;
the annular LED illuminating light source 4 is used for generating uniform shadowless light, and the illumination intensity of the annular LED illuminating light source can be adjusted according to a use scene;
the calibration plate can be a standard measurement scale (when the magnification of the imaging lens 5 is low) or a microscopic calibration scale (when the magnification of the imaging lens 5 is high) which is provided with scales and has a known length and is used for calibrating the single-pixel physical length of an image acquired by the industrial camera;
the three-dimensional translation stage 8 can realize three-axis fine translation and is used for selecting a measurement view field and a focused image;
the control system 13 is a home or industrial computer. The control system is provided with measurement control software and has the following functions: 1. displaying an industrial camera image in real time, and assisting lens focusing and field of view selection; 2. capturing an industrial camera image, selecting measurement mark points on two sides of the crack, and setting an initial reference image; 3. capturing an image in real time, and accurately calculating the sub-pixel displacement of the mark point by using a digital image correlation method so as to calculate the real-time crack opening displacement; 4. synchronously collecting a load signal output by the mechanical experiment machine 1 or feeding back crack opening displacement obtained by calculation to the experiment machine 1;
in order to improve the measurement accuracy and the measurement stability, a group of characteristic mark points 24 is respectively selected at two sides of the crack opening, and each group comprises 5-8 characteristic mark points. During measurement, the digital image correlation algorithm automatically identifies the selected marking points in the real-time captured image, and calculates the sub-pixel displacement of all the marking points by using a nonlinear optimization method. The calculation accuracy is better than 0.01 pixel. Finally, calculating the average relative displacement of the two groups of mark points as the opening displacement of the crack opening;
by selecting the imaging lens 5 with higher magnification, the measuring device of the utility model can measure the crack opening displacement of a small-size bending fracture sample;
through designing a high-transparent observation window in a low-temperature or high-temperature environment box, the measuring device of the utility model can be directly used for measuring the crack opening displacement of high-low temperature bending test;
through the high transparent observation window of liquid medium container design, the utility model discloses a measuring device can directly be used for the measurement of the crackle opening displacement of medium environment bending test.
A method for measuring by using the non-contact crack opening displacement measuring device for the bending fracture test comprises the following specific steps:
the method comprises the following steps: drawing a white background on two sides of a notch of a single-edge notch bending fracture sample, and spraying black spots to form random measuring speckles (shown in figure 5);
step two: and adjusting the span of the lower pressing head 16 of the bending tool, and placing the sample 2 on the lower pressing head of the bending tool with the notch facing downwards. The tripod 11 is adjusted so that the imaging lens 5 is in height alignment with the mirror 23 and is directed towards the sample plane. Observing a sample speckle image in real time through measurement control software, finely adjusting the position of a lens and focusing the image by using a three-dimensional translation stage 8, and adjusting the intensity of an annular LED illumination light source 4 to ensure that the acquired speckle image is clear and has moderate contrast;
step three: and capturing a speckle image as a starting reference image by measurement control software. And respectively selecting 1 group of pixel subsets as characteristic points at two sides of the crack, wherein each group comprises 5-8 points. Adjusting the size of the pixel subset to make the characteristic points suitable for the digital image correlation analysis;
step four: and starting measurement control software, entering a real-time analysis mode, and observing the fluctuation condition of the displacement data when the displacement data is not loaded. If the data fluctuation is too large, reselecting the marking points or spraying the speckle patterns again;
step five: starting a dynamics experiment machine test program, and starting loading;
step six: in the testing process, the measurement control software collects the speckle images in real time, completes digital image correlation analysis in the memory, calculates the relative displacement of the selected characteristic points of the speckle images relative to the reference image, and calculates the crack opening displacement. The measurement control software can synchronously acquire the load signals output by the mechanical experiment machine and draw a load-displacement curve in real time. The measurement control software can also feed back the calculated crack opening displacement signal to the mechanical experiment machine.
Step seven: and after the test is finished, stopping measuring the real-time analysis mode of the control software.
Examples
The use of the present invention will be described below with reference to a tungsten alloy as an example.
1. Description of the materials: the material in the examples is a tungsten alloy subjected to deformation processing. Due to the limitation of a processing technology, a block with a large volume cannot be prepared, and the fracture toughness of the material cannot be effectively measured by a conventional measuring means.
2. Test items: fracture toughness K of brittle materialICAnd (4) testing.
3. Sample type: three-point bending test piece with length of 22mm and span S of 16mm, and depth a of crack notch cut out in advance0About 1 mm.
4. Imaging system parameters: the magnification of the selected imaging lens is 2 times, the digital resolution of the industrial camera is 2048 multiplied by 1088 pixels, and the physical size of a single pixel of the corresponding acquired image of the optical measurement system is 2.904 mu m.
5. The test method comprises the following steps: the fracture toughness of the test specimens was measured based on linear elastic fracture mechanics according to ASTM E399-12 test standard, the specific procedure was as described above, with a load rate of about 8N/S.
6. And (3) test results: the linear displacement-load curve of the sample is shown in fig. 6. Although the total crack opening displacement is only 6 mu m before the sample is unstably broken, at least 90 data points can be obtained by each test by means of the high-precision characteristic of the utility model. All load-displacement data satisfy the linear elastic relationship. Fitting the curve elastic stage by using a straight line, making a straight line from the original point, wherein the slope of the straight line is 95% of that of the fitted straight line, and the load corresponding to the intersection point of the loading line displacement-load curve is marked as PQ. The conditional value K of the fracture toughness of the test specimen can be calculated by measuring the span S, the width W of the sample, the thickness B and the final crack length aQ. The test results are effective because the measurement results all meet the effectiveness criterion specified in the test standard, and the fracture toughness K of the test sampleIC＝KQ＝7.9MPa m1/2Consistent with data reported in the literature.
Claims (9)
1. A non-contact crack opening displacement measuring device for a bending fracture test is characterized by comprising
A mechanical experiment machine (1);
bending test tooling (3): the bending test tool (3) is loaded in the mechanical experiment machine (1), the bending test tool (3) comprises an upper pressure head (15) and two lower pressure heads (16), the sample (2) is clamped between the upper pressure head (15) and the lower pressure heads (16), the upper pressure head (15) is arranged in the middle of the sample (2), and the two lower pressure heads (16) are respectively arranged at two ends of the sample (2);
a digital image acquisition system: the system comprises an industrial camera (6), an imaging lens (5) arranged at the front end of the industrial camera, an annular LED illuminating light source (4) arranged at the front end of the imaging lens (5), a camera supporting system and a reflector (23); the reflector (23) is arranged below the sample (2) at an inclination angle of 45 degrees, the reflector (23) reflects light rays generated by the annular LED illumination light source (4) to the fracture surface of the sample, and simultaneously reflects the surface image of the fracture sample into the imaging lens (5);
control system (13): the industrial camera (6) and the mechanical experiment machine (1) are connected with the control system, the control system displays the image of the industrial camera (6) in real time, calculates the real-time crack opening displacement, synchronously acquires the load signal output by the mechanical experiment machine (1) or feeds back the calculated crack opening displacement to the mechanical experiment machine (1).
2. The apparatus of claim 1, wherein the mechanical testing machine (1) comprises an upper chuck, a lower chuck, a cross beam, a vertical frame and a base; the lower chuck is fixedly arranged on the base, the upper chuck is arranged on the lower side of the middle part of the cross beam, and the cross beam is movably arranged on the vertical frame.
3. The device according to claim 2, wherein the bending test fixture (3) further comprises an upper connecting rod (14), a bending fixture base (18), and a lower connecting rod (20);
go up connecting rod (14) one end and be connected with last pressure head (15), one end is connected with last chuck, connecting rod (20) one end is connected with crooked frock base (18) down, and one end is connected with lower chuck.
4. The device according to claim 3, characterized in that the upper surface of the bending tooling base (18) is provided with a sliding groove, the lower pressing head (16) is fixedly arranged on the bending tooling base (18) through the sliding groove, and the reflector (23) is fixedly arranged on the bending tooling base (18) through the reflector base (22);
the side face of the bending tool base (18) is provided with span scales (19), and the positions of the lower pressure head (16) and the reflector base (22) in the sliding groove are arranged according to the span scales (19).
5. The device according to claim 4, characterized in that the top ends of the upper pressure head (15) and the lower pressure head (16) are provided with tungsten steel bars, and the upper pressure head (15) and the lower pressure head (16) are in line contact with the sample (2) through the tungsten steel bars;
the upper surface of the lower pressure head (16) is provided with a centering scale (17) for centering the sample (2).
6. The device according to claim 1, characterized in that the camera support system comprises a fixed block (7), a three-dimensional translation stage (8), a connection plate (9), a section bar beam (10) and a tripod (11);
the industrial camera (6) is fixed at the tail of the imaging lens (5) through C-port threads, the imaging lens (5) is fixed on the three-dimensional translation table (8) through a fixing block (7), the three-dimensional translation table (8) is fixed on the profile cross beam (10) through a connecting plate (9), and the profile cross beam (10) is fixed on a tripod (11);
by adjusting the height, the direction and the position of the tripod (11), the imaging lens (5) is ensured to be aligned and vertical to the sample (2), and meanwhile, the working distance of the sample (2) on the lens is ensured.
7. The device according to claim 1, characterized in that the reflector (23) is fixed at the central position of the chute of the bending tool base (18) through a 45-degree inclined reflector base (22) and is opposite to the preformed notch of the sample (2); the reflector (23) is an optical lens with reflectivity higher than 98%.
8. The device according to claim 1, characterized in that the imaging lens (5) is a low distortion telecentric optical lens, for fixed focus or fixed zoom, the magnification being chosen according to the size of the sample to be measured;
the industrial camera (6) is a CCD or CMOS camera, and the resolution is selected according to the measurement precision requirement;
the annular LED illuminating light source (4) is used for generating uniform shadowless light, and the illumination intensity of the annular LED illuminating light source is adjusted according to a use scene.
9. The device according to claim 1, characterized in that the control system (13) is a computer in which measurement control software is arranged.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201920837549.4U CN210665329U (en) | 2019-06-05 | 2019-06-05 | Non-contact crack opening displacement measuring device for bending fracture test |
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| CN201920837549.4U CN210665329U (en) | 2019-06-05 | 2019-06-05 | Non-contact crack opening displacement measuring device for bending fracture test |
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| CN201920837549.4U Active CN210665329U (en) | 2019-06-05 | 2019-06-05 | Non-contact crack opening displacement measuring device for bending fracture test |
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Cited By (5)
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| CN110174315A (en) * | 2019-06-05 | 2019-08-27 | 南京理工大学 | The contactless crack opening displacement measuring device and method of bend fracture test |
| CN112067461A (en) * | 2020-08-24 | 2020-12-11 | 中国飞机强度研究所 | Composite material bending test device |
| CN112798445A (en) * | 2020-12-30 | 2021-05-14 | 蓬莱市超硬复合材料有限公司 | Bending strength detection system and method for micro-drill rod, storage medium and terminal |
| WO2021172252A1 (en) * | 2020-02-26 | 2021-09-02 | Ｊｆｅスチール株式会社 | Device and method for bend tests on metal sheet for automobile body and bend performance evaluation method using this device |
| CN113970490A (en) * | 2021-09-16 | 2022-01-25 | 武汉钢铁有限公司 | Limit bending strain detection device and limit bending strain detection method |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110174315A (en) * | 2019-06-05 | 2019-08-27 | 南京理工大学 | The contactless crack opening displacement measuring device and method of bend fracture test |
| WO2021172252A1 (en) * | 2020-02-26 | 2021-09-02 | Ｊｆｅスチール株式会社 | Device and method for bend tests on metal sheet for automobile body and bend performance evaluation method using this device |
| JP2021135128A (en) * | 2020-02-26 | 2021-09-13 | Ｊｆｅスチール株式会社 | Bending test equipment and bending test method for metal plate materials for automobile bodies and bending performance evaluation method by the bending test equipment |
| JP7222371B2 (en) | 2020-02-26 | 2023-02-15 | Ｊｆｅスチール株式会社 | Bending Test Facility and Bending Test Method for Metal Plate Materials for Automobile Bodies, and Bending Performance Evaluation Method Using the Bending Test Facility |
| CN112067461A (en) * | 2020-08-24 | 2020-12-11 | 中国飞机强度研究所 | Composite material bending test device |
| CN112798445A (en) * | 2020-12-30 | 2021-05-14 | 蓬莱市超硬复合材料有限公司 | Bending strength detection system and method for micro-drill rod, storage medium and terminal |
| CN112798445B (en) * | 2020-12-30 | 2022-01-28 | 蓬莱市超硬复合材料有限公司 | Bending strength detection system and method for micro-drill rod, storage medium and terminal |
| CN113970490A (en) * | 2021-09-16 | 2022-01-25 | 武汉钢铁有限公司 | Limit bending strain detection device and limit bending strain detection method |
| CN113970490B (en) * | 2021-09-16 | 2024-07-16 | 武汉钢铁有限公司 | Limit bending strain detection device and limit bending strain detection method |
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