A Shearing Performance Testing Device and Testing Method

Abstract

The present invention discloses a shearing performance testing device and a testing method. The testing device includes a first clamping mechanism, a second clamping mechanism, a driving mechanism, and a photographing mechanism. The first clamping mechanism includes a first fixed seat and a first pressing block. The first fixed seat is provided with a first installation groove. The first pressing block is arranged in the first installation groove and is detachably connected to the first fixed seat. The first pressing block and the first installation groove define a first clamping gap for clamping the first end of the sample. The second clamping mechanism includes a second fixed seat and a second pressing block. The second fixed seat is provided with a second installation groove. The second pressing block is arranged in the second installation groove and is detachably connected to the second fixed seat. The second pressing block and the second installation groove define a second clamping gap for clamping the second end of the sample. The driving mechanism is used to drive the first fixed seat and the second fixed seat to move in opposite directions. The present invention can accurately test the shearing performance of an object in a high-speed state, and the operation is simple and convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical property testing, and particularly to a shear property testing device and a testing method. Background Art

[0002] Shear deformation refers to the deformation in which an object, when subjected to a pair of external forces that are parallel to its cross-section, close to each other, equal in magnitude, and opposite in direction, causes the cross-section of the object to undergo relative dislocation. The cross-section where shear deformation occurs is called the shear plane, the shear plane is parallel to the direction of the external force, and the extrusion plane is perpendicular to the direction of the external force. Shear properties include shear stress, shear strain, and shear modulus, etc. Testing the shear strain and shear modulus of an object is of great significance in studying the rigidity of the object.

[0003] Currently, the testing technology for shear strain and shear modulus of an object under quasi-static conditions (the testing speed is generally 1 - 10 mm / min) is relatively mature, while the testing research on an object under high-speed conditions (the speed is generally above 200 mm / min) is less. The main difficulty lies in the fact that it is difficult to accurately measure the shear deformation amount per unit time of an object under high-speed conditions, and the measurement error is relatively large, resulting in difficulty in comprehensively measuring the shear properties of the object and difficulty in conducting a more comprehensive full-condition evaluation of the object. Summary of the Invention

[0004] The purpose of the present invention is to provide a shear property testing device that can accurately test the shear properties of an object under high-speed conditions, is simple and convenient to operate, has stable clamping of the object and is not easy to loosen, and has high fastening and reliability. In addition, the purpose of the present invention is also to provide a shear property testing method.

[0005] To achieve the above purpose, the present invention provides a shear property testing device for testing the shear strain of a sample, with speckles arranged on the surface of the sample. The shear property testing device includes:

[0006] A first clamping mechanism, which includes a first fixed seat and a first pressing block. The first fixed seat is provided with a first installation groove, the first pressing block is arranged in the first installation groove and is detachably connected to the first fixed seat. A first clamping gap for clamping the first end of the sample is defined between the first pressing block and the bottom of the first installation groove.

[0007] A second clamping mechanism, which includes a second fixed seat and a second pressing block. The second fixed seat is provided with a second installation groove, the second pressing block is arranged in the second installation groove and is detachably connected to the second fixed seat. A second clamping gap for clamping the second end of the sample is defined between the second pressing block and the bottom of the second installation groove.

[0008] A driving mechanism for driving the first fixed seat and the second fixed seat to move in opposite directions; and

[0009] An imaging mechanism for capturing a speckle image of the surface of a sample.

[0010] In some embodiments, the first fixed seat includes a first vertical section and a first horizontal section. The first end of the first vertical section is fixedly connected to the first end of the first horizontal section, and the first mounting groove is formed on the first vertical section;

[0011] The second fixed seat includes a second vertical section and a second horizontal section. The first end of the second vertical section is fixedly connected to the first end of the second horizontal section, and the second mounting groove is formed on the second vertical section;

[0012] Wherein, the second end of the first vertical section abuts against the second end of the second horizontal section, the second end of the second vertical section abuts against the second end of the first horizontal section, and the first mounting groove and the second mounting groove face each other; the driving mechanism is used to drive the first horizontal section and the second horizontal section to move in opposite directions in the up and down direction.

[0013] In some embodiments, a first positioning post extends outward from the second end of the first vertical section, and a first positioning hole for cooperating with the first positioning post for positioning is formed in the second end of the second horizontal section; a second positioning post extends outward from the second end of the second vertical section, and a second positioning hole for cooperating with the second positioning post for positioning is formed in the second end of the first horizontal section.

[0014] In some embodiments, a first horizontal platform for supporting the first end of the sample is provided on the bottom of the first mounting groove, and a second horizontal platform for supporting the second end of the sample is provided on the bottom of the second mounting groove. The first horizontal platform and the second horizontal platform face each other to keep the sample in a horizontal position.

[0015] In some embodiments, a centering pin is further included. A centering hole communicating with the second positioning hole is formed in the outer wall of the second end of the first horizontal section, and a through hole is formed in the second positioning post. The centering pin sequentially passes through the centering hole and the through hole.

[0016] In some embodiments, a first vertical reference line is provided in the middle of the outer wall of the first horizontal section, and a second vertical reference line collinear with the first vertical reference line is provided in the middle of the outer wall of the second horizontal section.

[0017] In some embodiments, the driving mechanism is a stretching hydraulic press, which includes a machine base and a piston rod. The first horizontal section is provided with a fixed threaded part fixedly connected to the machine base, and the second horizontal section is provided with a fixed end fixedly connected to the piston rod.

[0018] In some embodiments, the first pressing block is threadedly connected to the bottom of the first installation groove through a first locking threaded part, and the second pressing block is threadedly connected to the bottom of the second installation groove through a second locking threaded part.

[0019] In some embodiments, the photographing mechanism is a CCD camera.

[0020] Compared with the prior art, a shearing performance testing device of the present invention has the beneficial effects that:

[0021] The two ends of the sample are firmly clamped by the first clamping mechanism and the second clamping mechanism respectively. The driving mechanism drives the first fixed seat and the second fixed seat to move in two opposite directions at a certain stress and a relatively high speed, so that the sample undergoes shearing deformation at a high speed. During the process of the sample undergoing shearing deformation, the photographing mechanism captures and stores the speckle images on the surface of the sample in real time. Finally, the speckle images are exported and processed by an image analysis system, and the change curve of shear strain and time is generated by calculating the position change of the speckle along the time stamp. And the shear modulus is calculated according to the curve and the stress change of the driving mechanism, thereby accurately testing the shearing performance of the sample at a high speed. The operation is simple, and the stability, adjustability and reliability are relatively high. At the same time, the use of DIC technology is beneficial to improving the testing accuracy of the shearing deformation of the sample.

[0022] In addition, to achieve the above object, the present invention provides a shearing performance testing method, including the following steps:

[0023] S1. Recesses are respectively machined on both sides of the central position of the sample, and speckles are made around the recesses.

[0024] S2. The two ends of the sample are clamped by the first clamping mechanism and the second clamping mechanism respectively. Among them, the first clamping mechanism and the second clamping mechanism respectively include a fixed seat and a pressing block. The fixed seat is provided with an installation groove. The pressing block is arranged in the installation groove and is threadedly connected to the fixed seat through a locking threaded part. A clamping gap for clamping the sample is defined between the pressing block and the bottom of the installation groove.

[0025] S3. A virtual extensometer is established in the recess of the sample. The virtual extensometer includes a first direction extending along +45° and a second direction extending along -45°.

[0026] S4. Use a stretching hydraulic press to drive the first clamping mechanism and the second clamping mechanism to move in opposite directions at a predetermined speed and stress. At the same time, use a CCD camera to capture and store the speckle images of the sample within a unit time.

[0027] S5. Calculate the shear strain ε1 of the speckle in the first direction and the shear strain ε2 in the second direction within a unit time. After the shear strains ε1 and ε2 are superimposed, the shear strain ε of the sample within a unit time is formed. Then, calculate and obtain the shear modulus E based on the shear strain ε and the stress change value △σ of the stretching hydraulic press within a unit time. Description of the Drawings

[0028] Figure 1 is a diagram of the usage state of the shear performance testing device according to some embodiments of the present invention. The photographing mechanism is omitted in the figure.

[0029] Figure 2 is a schematic structural diagram of the shear performance testing device according to some embodiments of the present invention. The driving mechanism is omitted in the figure.

[0030] Figure 3 is Figure 2 the front view of, with the photographing mechanism omitted in the figure.

[0031] Figure 4 is Figure 2 the side exploded view of.

[0032] Figure 5 is a schematic structural diagram of the sample according to some embodiments of the present invention.

[0033] In the figure,

[0034] 1. Sample; 11. Recess

[0035] 2. First clamping mechanism; 21. First fixed seat; 211. First vertical section; 211a. First installation groove; 211b. First positioning post; 211c. First horizontal platform; 212. First horizontal section; 212a. Second positioning hole; 212b. Centering hole; 212c. First vertical reference line; 212d. Fixed threaded part; 22. First pressing block

[0036] 3. Second clamping mechanism; 31. Second fixed seat; 311. Second vertical section; 311a. Second installation groove; 311b. Second positioning post; 312. Second horizontal section; 312a. First positioning hole; 312b. Second vertical reference line; 312c. Fixed end; 32. Second pressing block

[0037] 4. Driving mechanism; 41. Machine base; 42. Piston rod

[0038] 5. Photographing mechanism

[0039] 6. Centering pin;

[0040] 7. First locking threaded part;

[0041] 8. Second locking threaded part;

[0042] 9. Quasi-static fixing bolt. Detailed implementation manner

[0043] The following combines the drawings and embodiments to further describe in detail the specific implementation manner of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0045] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0046] In the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is less than that of the second feature.

[0048] Embodiment 1

[0049] Please refer to Figure 1 -4, Embodiment 1 of the present invention provides a shear performance testing device for testing the shear strain of Sample 1. The surface of Sample 1 is provided with speckles (not shown in the figure). The shear performance testing device includes a first clamping mechanism 2, a second clamping mechanism 3, a driving mechanism 4 and a photographing mechanism 5; the first clamping mechanism 2 includes a first fixed seat 21 and a first pressing block 22. The first fixed seat 21 is provided with a first installation groove 211a. The first pressing block 22 is arranged in the first installation groove 211a and is detachably connected to the first fixed seat 21. The first pressing block 22 and the bottom of the first installation groove 211a define a first clamping gap for clamping the first end of Sample 1; the second clamping mechanism 3 includes a second fixed seat 31 and a second pressing block 32. The second fixed seat 31 is provided with a second installation groove 311a. The second pressing block 32 is arranged in the second installation groove 311a and is detachably connected to the second fixed seat 31. The second pressing block 32 and the bottom of the second installation groove 311a define a second clamping gap for clamping the second end of Sample 1; the driving mechanism 4 is used to drive the first fixed seat 21 and the second fixed seat 31 to move in opposite directions; the photographing mechanism 5 is used to photograph the speckle image on the surface of Sample 1.

[0050] Based on the above solution, the first clamping mechanism 2 and the second clamping mechanism 3 are respectively used to firmly clamp both ends of Sample 1. The driving mechanism 4 drives the first fixed seat 21 and the second fixed seat 31 to move in two opposite directions with a certain stress and at a relatively high speed, so that Sample 1 undergoes shear deformation at a high speed. During the shear deformation of Sample 1, the photographing mechanism 5 continuously photographs the speckle image on the surface of Sample 1 and stores it. Finally, the speckle image is exported and processed by an image analysis system, and the shear strain-time change curve is generated by calculating the position change of the speckle along the time stamp. According to the curve and the stress change of the driving mechanism 4, the shear modulus is calculated, thereby accurately testing the shear performance of Sample 1 at a high speed. The operation is simple, and the stability, adjustability and reliability are relatively high. At the same time, the use of the DIC technology is beneficial to improving the test accuracy of the shear deformation of Sample 1.

[0051] As an embodiment of the present invention, please refer to Figure 2 -4. The first fixing seat 21 includes a first vertical section 211 and a first horizontal section 212. The first end of the first vertical section 211 is fixedly connected to the first end of the first horizontal section 212, and a first mounting groove 211a is formed on the first vertical section 211. The second fixing seat 31 includes a second vertical section 311 and a second horizontal section 312. The first end of the second vertical section 311 is fixedly connected to the first end of the second horizontal section 312, and a second mounting groove 311a is formed on the second vertical section 311. Wherein, the second end of the first vertical section 211 abuts against the second end of the second horizontal section 312, the second end of the second vertical section 311 abuts against the second end of the first horizontal section 212, and the first mounting groove 211a and the second mounting groove 311a are oppositely arranged. The driving mechanism 4 is used to drive the first horizontal section 212 and the second horizontal section 312 to move in opposite directions in the up and down direction. Wherein, the first vertical section 211 and the first horizontal section 212 are of an integrally formed structure, and the second vertical section 311 and the second horizontal section 312 are of an integrally formed structure to improve the overall structural strength of the first fixing seat 21 and the second fixing seat 31. The first fixing seat 21 and the second fixing seat 31 enclose a square-shaped structure, wherein the first vertical section 211 and the second vertical section 311 are spaced apart by an appropriate distance. The sample 1 is clamped between the first vertical section 211 and the second vertical section 311 and undergoes shear deformation, and the speckles are disposed on the area of the sample 1 between the first vertical section 211 and the second vertical section 311 so that the photographing mechanism 5 can acquire the speckle image. Further, the left and right sides of the first mounting groove 211a respectively penetrate through the left and right outer sides of the first vertical section 211, and the left and right sides of the second mounting groove 311a respectively penetrate through the left and right outer sides of the second vertical section 311, so that the sample 1 can be inserted into the first clamping gap and the second clamping gap from the left opening of the first mounting groove 211a or the right opening of the second mounting groove 311a and then clamped.

[0052] Further, please refer to Figure 3, a second end of the first vertical section 211 extends outwardly with a first positioning post 211b, and a first positioning hole 312a for cooperating with the first positioning post 211b for positioning is provided at a second end of the second horizontal section 312; a second end of the second vertical section 311 extends outwardly with a second positioning post 311b, and a second positioning hole 212a for cooperating with the second positioning post 311b for positioning is provided at a second end of the first horizontal section 212. The first positioning post 211b and the second positioning post 311b can be a cylinder or a square post or a prism, etc., which is not limited herein. The shapes of the first positioning hole 312a and the second positioning hole 212a are respectively adapted to the shapes of the first positioning post 211b and the second positioning post 311b. In this way, the first positioning post 211b cooperates with the first positioning hole 312a for positioning, and the second positioning post 311b cooperates with the second positioning hole 212a for positioning, so as to ensure that the clamped sample 1 and the first horizontal section 212 and the second horizontal section 312 are on the same plane. When the driving mechanism 4 drives the first horizontal section 212 and the second horizontal section 312 to move in opposite directions in the up and down direction, it is ensured that the sample 1 is subjected to two opposite forces in the up and down direction, so that the sample 1 undergoes shear deformation.

[0053] Further, in some embodiments, please refer to Figure 4 , a first horizontal platform 211c for supporting a first end of the sample 1 is provided on an inner wall of the first installation groove 211a, and a second horizontal platform (not shown in the figure) for supporting a second end of the sample 1 is provided on an inner wall of the second installation groove 311a. The first horizontal platform 211c and the second horizontal platform are oppositely arranged to make the sample 1 in a horizontal position. Among them, before the sample 1 is clamped, the first horizontal platform 211c and the second horizontal platform are at the same horizontal height, so that the sample 1 is in a horizontal state after being inserted into the first clamping gap and the second clamping gap, so that the sample 1 is in a vertical and horizontal state before undergoing shear deformation, ensuring that the directions of the two opposite forces borne by the sample 1 are the same as the directions of the two opposite forces of the first horizontal section 212 and the second horizontal section 312.

[0054] In some embodiments, please refer to Figure 3, To facilitate the tester to adjust the first horizontal platform 211c and the second horizontal platform to be at the same horizontal height, the shear performance testing device of the present invention further includes a centering pin 6. A centering hole 212b communicating with the second positioning hole 212a is formed in the outer wall of the second end of the first horizontal section 212, and a through hole (not shown in the figure) is formed in the second positioning post 311b. The centering pin 6 sequentially passes through the centering hole 212b and the through hole. In this way, the centering pin 6 sequentially passes through the centering hole 212b and the through hole to ensure that the first horizontal platform 211c and the second horizontal platform are at the same horizontal height. Subsequently, both ends of the sample 1 are respectively inserted into the first clamping gap and the second clamping gap and then clamped. Finally, the centering pin 6 needs to be pulled out before the driving mechanism 4 drives the first horizontal section 212 and the second horizontal section 312 to move in opposite directions in the up and down direction.

[0055] In some embodiments, please refer to Figure 2 , 3 , a first vertical reference line 212c is provided in the middle of the outer wall of the first horizontal section 212, and a second vertical reference line 312b collinear with the first vertical reference line 212c is provided in the middle of the outer wall of the second horizontal section 312. Among them, please refer to Figure 5 , a concave portion 11 where shear deformation occurs is preset in the middle of the sample 1. When the sample 1 is subjected to opposite forces in the up and down direction, the sample 1 undergoes shear deformation along the concave portion 11 and then breaks, and at the same time, the speckles are evenly distributed around the concave portion 11. When the sample 1 is being clamped, adjust the first vertical reference line 212c, the middle of the concave portion 11, and the second vertical reference line 312b to be on the same vertical line to ensure that the concave portion 11 is within the shooting range of the shooting mechanism 5, so as to obtain the speckle image on the surface of the sample 1 by shooting.

[0056] In some embodiments, please refer to Figure 1 -2, the driving mechanism 4 is a tensile hydraulic press. Specifically, the tensile hydraulic press includes a machine base 41 and a piston rod 42. The first horizontal section 212 is provided with a fixed threaded member 212d fixedly connected to the machine base 41, and the second horizontal section 312 is provided with a fixed end 312c fixedly connected to the piston rod 42. Specifically, the driving mechanism 4 is, for example, a ZWICK high-speed tensile machine. Correspondingly, the first horizontal section 212 is provided with threaded holes threadedly connected to the fixed threaded member 212d. The number of threaded holes can be two, and two corresponding fixed threaded members 212d are provided to improve the connection stability between the first horizontal section 212 and the machine base 41. The fixed end 312c can be in the shape of a rod, and it can be fixedly connected to the piston rod 42 by screwing, clamping, sleeving or other connection methods.

[0057] In some embodiments, please refer to Figure 2-4. The first pressing block 22 is threadedly connected to the bottom of the first installation groove 211a through the first locking threaded member 7, and the second pressing block 32 is threadedly connected to the bottom of the second installation groove 311a through the second locking threaded member 8. The first locking threaded member 7 and the second locking threaded member 8 are respectively bolts or screws, and threaded holes are respectively provided at the bottoms of the first installation groove 211a and the second installation groove 311a. For example, the numbers of the first locking threaded member 7 and the second locking threaded member 8 are both two, so as to improve the connection stability of the first pressing block 22 in the first installation groove 211a and the second pressing block 32 in the second installation groove 311a, thereby improving the clamping stability of the sample 1.

[0058] In some embodiments, the photographing mechanism 5 is a CCD camera. A CCD (charge coupled device) is provided inside the CCD camera. The CCD can convert an optical image into a digital signal for storage and transfer, with the purpose of converting the captured speckle image into a digital signal and then exporting it for calculation. Further, a light source can be used to irradiate the speckle to improve the clarity of the speckle, facilitating the CCD camera to photograph the speckle.

[0059] Further, the image analysis and processing of the speckle image are specifically as follows: Please refer to Figure 1 -5. A virtual extensometer (+45° and -45°) is established. The concave portion 11 of the sample 1 is placed in the middle of the virtual extensometer. During the process that the driving mechanism 4 drives the first horizontal section 212 and the second horizontal section 312 to move in opposite directions, the position of the speckle on the sample 1 changes with time. By calculating the shear strain ε1 of the speckle position relative to +45° and the shear strain ε2 relative to -45° of the sample per unit time, after ε1 and ε2 are superimposed, the shear strain ε of the sample 1 is formed. A shear strain curve graph is generated using the shear strain ε and time. At the same time, the stress value σ of the tensile hydraulic press changing with time is exported. The shear modulus E is obtained by dividing the change △σ of the stress value of the sample 1 per unit time by the change △ε of the shear strain per unit time. A shear modulus curve graph is generated using the shear modulus E and time, facilitating the tester to intuitively observe the shear performance of the sample 1.

[0060] It should be noted that the shear performance testing device of the present invention can also be used to test the shear performance under quasi-static conditions. Specifically, please refer to Figure 3 , quasi-static fixing bolts 9 are respectively connected to the first horizontal section 212 and the second horizontal section 312. The first horizontal section 212 and the second horizontal section 312 are respectively assembled with a conventional tensile machine through the quasi-static fixing bolts 9 to realize the testing of the shear performance under quasi-static conditions.

[0061] In summary, Embodiment 1 of the present invention provides a shear performance testing device, which uses a first clamping mechanism 2 and a second clamping mechanism 3 to firmly clamp both ends of a sample 1 respectively. A driving mechanism 4 drives a first fixed seat 21 and a second fixed seat 31 to move in two opposite directions at a certain stress and a relatively high speed, so that the sample 1 undergoes shear deformation at a high speed. During the shear deformation of the sample 1, a photographing mechanism 5 captures and stores the speckle image on the surface of the sample 1 in real time. Finally, the speckle image is exported and processed by an image analysis system, and the shear strain and time variation curve is generated by calculating the position change of the speckle along the time stamp. And the shear modulus is calculated according to the curve and the stress change of the driving mechanism 4, thereby accurately testing the shear performance of the sample 1 at a high speed. The operation is simple, and the stability, adjustability and reliability are relatively high. At the same time, the use of DIC technology is beneficial to improving the test accuracy of the shear deformation of the sample 1.

[0062] Embodiment 2

[0063] Embodiment 2 of the present invention discloses a shear performance testing method, including the following steps:

[0064] S1. Recesses are respectively machined on both sides of the central position of the sample, and speckles are made around the recesses. Among them, for example, after laser irradiation on the surface of the sample, the surface of the sample is distributed with speckles, and the speckles can be distributed near the recesses. After the surface of the sample is irradiated by the laser, the surface presents a granular structure.

[0065] S2. A first clamping mechanism and a second clamping mechanism are respectively used to clamp both ends of the sample. Among them, the first clamping mechanism and the second clamping mechanism respectively include a fixed seat and a pressing block. The fixed seat is provided with an installation groove, the pressing block is arranged in the installation groove and is threadedly connected with the fixed seat through a locking threaded member. A clamping gap for clamping the sample is defined between the pressing block and the bottom of the installation groove. Specifically, first insert the end of the sample between the fixed seat and the pressing block, and rotate the locking threaded member to drive the pressing block to move to reduce the clamping gap, so that the pressing block can press on the sample, thereby realizing the clamping and fixing effect on both ends of the sample.

[0066] S3. A virtual extensometer is established in the recess of the sample. Among them, the virtual extensometer includes a first direction extending along +45° and a second direction extending along -45°.

[0067] S4. Use a tensile hydraulic press to drive the first clamping mechanism and the second clamping mechanism to move in opposite directions at a predetermined speed and stress, and at the same time use a CCD camera to capture and store the speckle image of the sample per unit time. When the tensile hydraulic press drives the first clamping mechanism and the second clamping mechanism to move in opposite directions, a pair of opposite acting forces are applied to the position of the recess of the sample to cause deformation, so that the speckles near the recess are displaced, and the speckle image per unit time is captured by the CCD camera.

[0068] S5. Calculate the shear strain ε1 of the speckle along the first direction and the shear strain ε2 along the second direction within a unit time. After the shear strains ε1 and ε2 are superimposed, the shear strain ε of the sample within a unit time is formed. Then, according to the shear strain ε and the stress change value △σ of the tensile hydraulic press within a unit time, the shear modulus E is calculated. Generate a shear strain curve graph based on the shear strain ε and time, and generate a shear modulus curve graph using the shear modulus E and time, which is convenient for the tester to visually observe the shear performance of sample 1.

[0069] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0070] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A shear performance testing device for testing the shear strain of a sample, wherein the surface of the sample is provided with speckles, characterized in that, Comprising: A first clamping mechanism, the first clamping mechanism includes a first fixed seat and a first pressing block. The first fixed seat is provided with a first installation groove. The first pressing block is arranged in the first installation groove and is detachably connected to the first fixed seat. A first clamping gap for clamping the first end of the sample is defined between the first pressing block and the bottom of the first installation groove. The first fixed seat includes a first vertical section and a first horizontal section. The first end of the first vertical section is fixedly connected to the first end of the first horizontal section. The first installation groove is opened on the first vertical section; A second clamping mechanism, the second clamping mechanism includes a second fixed seat and a second pressing block. The second fixed seat is provided with a second installation groove. The second pressing block is arranged in the second installation groove and is detachably connected to the second fixed seat. A second clamping gap for clamping the second end of the sample is defined between the second pressing block and the bottom of the second installation groove. The second fixed seat includes a second vertical section and a second horizontal section. The first end of the second vertical section is fixedly connected to the first end of the second horizontal section. The second installation groove is opened on the second vertical section; A driving mechanism for driving the first fixed seat and the second fixed seat to move in opposite directions; and A photographing mechanism for photographing the speckle image on the surface of the sample; Wherein, the second end of the first vertical section abuts against the second end of the second horizontal section, the second end of the second vertical section abuts against the second end of the first horizontal section, and the first installation groove and the second installation groove face each other. The driving mechanism is used to drive the first horizontal section and the second horizontal section to move in opposite directions in the up and down direction. A first horizontal platform for supporting the first end of the sample is provided on the bottom of the first installation groove, and a second horizontal platform for supporting the second end of the sample is provided on the bottom of the second installation groove. The first horizontal platform and the second horizontal platform face each other to keep the sample in a horizontal position.

2. The shear performance testing device according to claim 1, characterized in that, A first positioning post extends outward from the second end of the first vertical section, and a first positioning hole for cooperating with the first positioning post for positioning is opened at the second end of the second horizontal section. A second positioning post extends outward from the second end of the second vertical section, and a second positioning hole for cooperating with the second positioning post for positioning is opened at the second end of the first horizontal section.

3. The shear performance testing device according to claim 2, characterized in that, It further includes a centering pin. A centering hole communicating with the second positioning hole is opened on the outer wall of the second end of the first horizontal section, and a through hole is opened in the second positioning post. The centering pin sequentially passes through the centering hole and the through hole.

4. The shear performance testing device according to claim 1, characterized in that, A first vertical reference line is provided in the middle of the outer wall of the first horizontal section, and a second vertical reference line collinear with the first vertical reference line is provided in the middle of the outer wall of the second horizontal section.

5. The shear performance testing device according to any one of claims 1-4, characterized in that, The driving mechanism is a stretching hydraulic press. The stretching hydraulic press includes a machine base and a piston rod. The first horizontal section is provided with a fixed threaded part fixedly connected to the machine base, and the second horizontal section is provided with a fixed end fixedly connected to the piston rod.

6. The shear performance testing device according to claim 1, characterized in that, The first pressing block is threadedly connected to the bottom of the first installation groove through a first locking threaded member, and the second pressing block is threadedly connected to the bottom of the second installation groove through a second locking threaded member.

7. The shear performance testing device according to claim 1, characterized in that, The photographing mechanism is a CCD camera.

8. A shear performance testing method, characterized in that, It includes the following steps: S1. Concave portions are respectively machined on both sides of the central position of the sample, and speckles are made around the concave portions; S2. The two ends of the sample are respectively clamped by a first clamping mechanism and a second clamping mechanism. Among them, the first clamping mechanism and the second clamping mechanism respectively include a fixed seat and a pressing block. The fixed seat is provided with an installation groove. The pressing block is arranged in the installation groove and is threadedly connected to the fixed seat through a locking threaded member. A clamping gap for clamping the sample is defined between the pressing block and the bottom of the installation groove; S3. A virtual extensometer is established in the concave portion of the sample. The virtual extensometer includes a first direction extending along +45° and a second direction extending along -45°; S4. A tensile hydraulic press is used to drive the first clamping mechanism and the second clamping mechanism to move in opposite directions at a predetermined speed and stress. At the same time, a CCD camera is used to photograph the speckle image of the sample within a unit time and store it; S5. Calculate the shear strain ε1 of the speckle along the first direction and the shear strain ε2 along the second direction within a unit time. After the shear strains ε1 and ε2 are superimposed, the shear strain ε of the sample within a unit time is formed. Then, according to the shear strain ε and the stress change value △σ of the tensile hydraulic press within a unit time, the shear modulus E is calculated and obtained.

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