Test device and test method for realizing uniform tensile loading of flat plate sample in high-temperature furnace

Abstract

According to the test device and the test method for realizing uniform tensile loading of the flat sample in the high-temperature furnace provided by the invention, the rotatable concentric block and the contact surface matched with the clamping end of the sample in shape are arranged in the clamp structure, so that the load can be uniformly transmitted along the axis of the sample; the problem of stress concentration caused by improper clamping is avoided, so that the flat sample is ensured to be fractured within the range of the working section, the risk of early failure of the root of the clamp is reduced, and the authenticity and reliability of high-temperature tensile test data are improved.

Description

Technical Field

[0001] This invention belongs to the field of materials mechanical strength testing technology, specifically relating to a test device and test method for achieving uniform tensile loading of flat plate specimens in a high-temperature furnace. Background Technology

[0002] Currently, commonly used mechanical testing machines with small-sized high-temperature furnaces face limitations in high-temperature tensile testing due to the large overall size of the machine's clamps, which prevent direct placement within the furnace cavity for loading. This necessitates restrictions on the clamping and loading methods for flat specimens. To address these issues, existing technologies typically employ two alternative methods:

[0003] The first method involves designing and processing long specimens with the clamping end located outside the furnace, directly clamped and loaded by the testing machine's grippers. While this method avoids the grippers entering the furnace cavity, it also has significant drawbacks: Firstly, it requires high-quality raw materials for the specimens. In some cases, due to limitations in the size of the raw materials, it is difficult to process specimens of sufficient length, thus limiting the applicability of this method. Secondly, it requires high processing capabilities. Excessively long specimens may cause inconvenience in clamping and uneven temperature distribution, leading to failure and fracture at areas with high temperature gradients, resulting in inaccurate strength test results.

[0004] The second method involves using a loading rod for loading. This involves machining holes at both ends of the sample, connecting the loading rod to the sample ends via pins, and then extending the loading rod into the high-temperature furnace cavity to achieve loading. This method allows the entire sample to be placed inside the furnace, but it also has significant drawbacks: Firstly, the holes at the sample ends introduce stress concentration, which can easily lead to premature failure of the clamping ends, resulting in test failure. Secondly, pin loading requires high precision in hole machining, and machining errors will directly affect the uniformity of loading and the reliability of the test results.

[0005] A high-temperature tensile testing clamp and testing machine are disclosed in invention patent CN 109991072 B. This invention employs a ventilated structural design to prevent deformation of the high-temperature test specimen from causing dead cavities in the clamping section, making the specimen easy to disassemble and avoiding the problem of specimen fragments remaining in the clamp and rendering it unusable. Similarly, invention patent CN114894634 B discloses a metal superplasticity testing device and method, whose fixing groove allows for high-temperature tensile testing with smaller specimens on a high-temperature tensile testing machine. However, both are limited by the specimen processing conditions, making it difficult to achieve perfect symmetry at the clamping ends. This prevents the clamping ends from fully conforming to the test fixture, leading to stress concentration at the clamping ends and premature fracture.

[0006] In summary, existing technical solutions are either limited by the size of the specimen and processing conditions, or suffer from stress concentration and premature breakage at the clamping end due to structural design. Both make it difficult to achieve uniform tensile loading of small-sized flat plate specimens in a high-temperature furnace. Therefore, there is an urgent need to propose a new high-temperature tensile testing device that can reliably clamp and uniformly load flat plate specimens within the limited space of the high-temperature furnace cavity, and avoid opening holes at the specimen ends, thus solving the problems caused by processing errors and size limitations, thereby ensuring the accuracy and stability of high-temperature tensile testing. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies in the tensile testing of flat plate specimens under high-temperature conditions, such as stress concentration at the clamping end, uneven force distribution, and the risk of damage to the testing machine clamps when directly clamped in a high-temperature furnace. This invention provides a testing device and method for achieving uniform tensile loading of flat plate specimens in a high-temperature furnace. By incorporating rotatable concentric blocks and contact surfaces that match the shape of the specimen clamping end into the clamping structure, the load can be uniformly transmitted along the specimen axis, avoiding stress concentration caused by improper clamping. This ensures that the flat plate specimen fractures within the working range, reduces the risk of premature failure at the clamping root, and improves the authenticity and reliability of high-temperature tensile test data.

[0008] To achieve the above objectives, the technical solution provided by this invention is:

[0009] A test device for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace includes a flat plate specimen (200), characterized in that it further includes a first clamp (110), a second clamp (120) and a rotating clamp (130).

[0010] The flat plate specimen (200) includes two holding ends (210) and a working section (220) located between them;

[0011] The first clamp (110) includes a first groove portion (113) and a first connecting portion (114), wherein the first groove portion (113) has a groove on its side, which is composed of a first trapezoidal groove (111) and two first arc grooves (112) located on its left and right sides;

[0012] The second clamp (120) includes a second groove (123) and a second connecting part (124), wherein the second groove (123) has a groove on its side, which is composed of a second trapezoidal groove (121) and two second arc grooves (122) located on its left and right sides;

[0013] The rotating clamp (130) has an arc-shaped structure and consists of two sets of two sub-clamps that are symmetrical from left to right, and are respectively placed in two first arc grooves (112) and two second arc grooves (122);

[0014] The first clamp 110 and the second clamp 120 have the same structure and are symmetrically arranged at both ends of the flat plate specimen (200). The first groove (113) and the second groove (123) respectively clamp the holding end (210) and the rotating clamp (130) of the flat plate specimen (200) to jointly clamp the flat plate specimen (200). The first connecting part (114) and the second connecting part (124) are directly connected to the loading end of the testing machine, so that the external tensile load is transmitted along the axial direction of the flat plate specimen (200).

[0015] Furthermore, both bearing ends (210) of the flat plate sample (200) are trapezoidal structures.

[0016] Furthermore, the first groove (113) and the first connecting part (114) are coaxial cylindrical structures; the second groove (123) and the second connecting part (124) are coaxial cylindrical structures; the widths of the first groove (113) and the second groove (123) are the same and both are greater than the width of the flat plate sample (200).

[0017] Furthermore, the first trapezoidal groove (111) and the first circular arc groove (112) have the same depth, and the two sides of the first trapezoidal groove (111) coincide with the chords of the two first circular arc grooves (112); the second trapezoidal groove (121) and the second circular arc groove (122) have the same depth, and the two sides of the second trapezoidal groove (121) coincide with the chords of the two second circular arc grooves (122).

[0018] Furthermore, the two sets of rotating clamps (130) are arranged concentrically with the first arc groove (112) and the second arc groove (122), respectively, and are in contact with the left and right sides of the two holding ends (210) of the flat plate sample (200) placed in the first trapezoidal groove (111) and the second trapezoidal groove (121), respectively.

[0019] Furthermore, the rotating clamp (130) can rotate freely and automatically adjust its angle during the clamping process to achieve force self-adjustment, thereby ensuring that the flat plate sample is subjected to uniform force during tensile loading.

[0020] Furthermore, the contact area between the rotating clamp (130) and the first clamp (110) and the second clamp (120) is larger than the direct contact area between the clamping end (210) and the first clamp (110) and the second clamp (120), thereby increasing the uniformity of force distribution.

[0021] Furthermore, the first trapezoidal groove (111) and the second trapezoidal groove (121) are planar groove structures, which respectively cooperate with the two holding ends (210) of the flat plate sample (200); the structures of the first arc groove (112) and the second arc groove (122) respectively cooperate with the rotating clamp (130).

[0022] The present invention also proposes a test method based on the above-mentioned test apparatus, characterized in that it specifically includes:

[0023] Step 1: Sample preparation

[0024] Clamping ends (210) are prepared at both ends of the working section (220) of the sample to ensure that the shape of the clamping end (210) of the processed flat sample (200) matches the trapezoidal groove of the first clamp (110) and the second clamp (120) in the test device.

[0025] Step 2: Assemble the test apparatus and sample:

[0026] Step 2-1: Place the two clamping ends (210) of the flat plate sample (200) into the first trapezoidal groove (111) and the second trapezoidal groove (121) respectively;

[0027] Step 2-2: Place rotating clamping blocks (130) on both sides of the first trapezoidal groove (111) and the second trapezoidal groove (121), that is, the rotating clamping blocks (130) are located in the first circular arc groove (112) and the second circular arc groove (122);

[0028] Steps 2-3: Adjust the position of the clamps so that the rotating clamp (130) fits tightly against the wall of the arc groove, and the sample clamping end (210) fits tightly against the wall of the trapezoidal groove and the two rotating clamps (130) on the left and right. At the same time, ensure that the rotating clamp (130) can rotate around the center during the clamping process to automatically adjust the angle and maintain uniform force, so as to achieve self-adjustment of force during loading, avoid single-point force and stress concentration, and then firmly position the flat plate sample (200) by bolts or clamps.

[0029] Step 3: Install the assembled testing device onto the testing machine:

[0030] The outer ends of the first clamp (110) and the second clamp (120), namely the first connecting part (114) and the second connecting part (124), are respectively connected to the chuck of the testing machine so that the tensile load of the testing machine can be simultaneously transmitted to the upper and lower clamping ends (210) of the specimen.

[0031] Step 4: Apply load:

[0032] Start the testing machine and gradually increase the tensile load. Observe the deformation of the specimen during the loading process. During this process, the rotating clamp (130) can automatically adjust the clamping angle with the loading process, thereby ensuring that the two ends of the specimen are subjected to uniform force and avoiding eccentricity or stress concentration caused by direct clamping.

[0033] Step 5, Testing and Recording:

[0034] During the process of the specimen being stretched to fracture, the tensile load-displacement curve is recorded, and the mechanical parameters such as the ultimate strength and elastic modulus of the specimen are determined.

[0035] The beneficial effects of this invention are:

[0036] 1. This invention matches the clamping end of the flat plate specimen with the cylindrical fixture body and the rotatable clamping block, so that the clamping end is subjected to uniform force and the load is smoothly transmitted along the working section, realizing uniform tensile testing of the specimen as a whole, ensuring that the fracture location is in the working section, and improving the accuracy and reliability of the tensile test.

[0037] 2. The present invention automatically adjusts the angle of the rotatable clamping block to make the clamping end fit more evenly with the clamp, avoid local stress concentration and end damage, and ensure stable clamping force.

[0038] 3. This invention utilizes a concentric circle structure and a rotatable clamp to automatically center the sample, reducing eccentric forces and bending moments, ensuring consistent loading axes, and achieving a pure tensile state.

[0039] 4. This invention effectively protects the sample ends, prevents indentation and slippage, and improves test repeatability through a precisely matched fixture structure and large-area contact.

[0040] 5. This invention ensures uniform friction and stable loading conditions, making the measurement of tensile mechanical parameters more reliable and significantly improving the accuracy and repeatability of test data;

[0041] 6. The present invention has a stable structure, reducing the risk of clamp slippage and sample breakage, making operation safer;

[0042] 7. This invention is applicable to high-temperature tensile testing. By using a transition clamp to isolate the specimen from the testing machine clamp, it ensures that the specimen is subjected to uniform stress under high-temperature conditions and effectively protects the testing machine clamp, thus extending the service life of the equipment.

[0043] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0044] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0045] Figure 1 A three-dimensional structural schematic diagram of the experimental apparatus provided by the present invention;

[0046] Figure 2 A first-view structural schematic diagram of the experimental device provided by the present invention;

[0047] Figure 3 Exploded view of the experimental apparatus provided by the present invention;

[0048] Figure 4 A perspective view of the flat plate sample provided by the present invention;

[0049] Figure 5 A three-dimensional structural schematic diagram of the first clamp provided by the present invention;

[0050] Figure 6 This is a schematic diagram of the first view structure of the first clamp provided by the present invention;

[0051] Figure 7 A perspective view of the rotating clamping block provided by the present invention;

[0052] Figure 8 A flowchart of the test method provided by the present invention;

[0053] Explanation of reference numerals in the attached figures:

[0054] 110-First clamp; 111-First trapezoidal groove; 112-First circular arc groove; 113-First recessed part; 114-First connecting part; 120-Second clamp; 121-Second trapezoidal groove; 122-Second circular arc groove; 123-First recessed part; 124-Second connecting part; 130-Rotating clamping block; 200-Flat plate sample; 210-Clamping end; 220-Working section. Detailed Implementation

[0055] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings, and the technical solutions in the embodiments will be clearly and completely explained. The same or similar reference numerals shown in the accompanying drawings represent the same or functionally similar elements. It should be particularly noted that the embodiments described below are exemplary and are only used to illustrate the present invention, and should not be regarded as limiting it.

[0056] In the description of this invention, it should be noted that when terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are used, these orientations or positional relationships are based on the orientation in the accompanying drawings or the conventional placement of the product during use, and are intended to facilitate the description and simplification of the invention, rather than as a limitation on the specific orientation of the device or component in actual operation. Therefore, these terms should not be construed as constraints on the invention. Furthermore, terms such as "first" and "second" are only used to distinguish different components and do not represent their relative importance.

[0057] To further clarify, the terms "horizontal" and "vertical" mentioned in the description of this invention do not require the components to be absolutely horizontal or vertical, but rather allow for a certain degree of tilt. For example, "horizontal" only indicates that it is more horizontal relative to the direction of "vertical," and does not mean that the structure must be completely horizontal; a certain degree of tilt is allowed.

[0058] Furthermore, the terms "set," "install," "connect," or "link" used in the description of this invention should be interpreted broadly. They can refer to fixed connections, detachable connections, or integrated connections; they can refer to mechanical connections or electrical connections; they can be direct connections or indirect connections through an intermediate medium, or even connections within two components. Those skilled in the art will understand the specific meaning of these terms in this invention according to the specific circumstances.

[0059] Please see Figures 1 to 3 This invention provides a testing device for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace, comprising a first clamp 110, a second clamp 120, and a rotating clamp 130. Using this testing device to clamp the flat plate specimen 200 and then perform a tensile loading test enables uniform tensile loading of the specimen, thereby reducing stress concentration and uneven deformation, and improving the accuracy and reliability of the tensile test. Specifically:

[0060] Please see Figure 4 The flat plate sample 200 of this embodiment of the invention includes two holding ends 210 and a working section 220 located between them, wherein the holding ends 210 are trapezoidal structures;

[0061] Please continue reading. Figure 5 and Figure 6 The first clamp 110 includes a first groove portion 113 and a first connecting portion 114, which are coaxial cylindrical structures. The first groove portion 113 has a groove on its side, which is composed of a first trapezoidal groove 111 and two first arc grooves 112 located on its left and right sides. The first trapezoidal groove 111 and the first arc groove 112 have the same depth, and the two sides of the first trapezoidal groove 111 coincide with the chords of the two first arc grooves 112.

[0062] The second clamp 120 has the same structure as the first clamp 110, including a second groove portion 123 and a second connecting portion 124, which is a coaxial cylindrical structure. The second groove portion 123 has a groove on its side, which is composed of a second trapezoidal groove 121 and two second arc grooves 122 located on its left and right sides. The second trapezoidal groove 121 and the second arc groove 122 have the same depth, and the two sides of the second trapezoidal groove 121 coincide with the chord of the two second arc grooves 122.

[0063] Please continue reading. Figure 7 The rotating clamp 130 has an arc-shaped structure.

[0064] Please continue reading. Figures 1 to 3 In this embodiment of the invention, the first clamp 110 and the second clamp 120 are symmetrically arranged at both ends of the flat plate specimen 200. Specifically, the first groove portion 113 and the second groove portion 123 respectively clamp the holding end 210 and the rotating clamping block 130 of the flat plate specimen 200, thereby jointly clamping the flat plate specimen 200; the first connecting portion 114 and the second connecting portion 124 are directly connected to the loading end of the testing machine, so that the external tensile load is transmitted along the axial direction of the flat plate specimen 200.

[0065] Preferably, the widths of the first groove portion 113 and the second groove portion 123 are the same and both are greater than the width of the flat plate sample 200.

[0066] The rotating clamp 130 of this embodiment of the invention consists of two sets of two symmetrical sub-clamps, which are respectively placed in two first arc grooves 112 and two second arc grooves 122, and contact the left and right sides of the two holding ends 210 of the flat plate sample 200, which are respectively placed in the first trapezoidal groove 111 and the second trapezoidal groove 121. The rotating clamp 130 can rotate around the rotation axis and achieve self-adjustment during the test loading process, thereby ensuring that the flat plate sample 200 is subjected to uniform force during the tensile loading process, avoiding stress concentration and skewed fracture caused by uneven clamping. Furthermore, the contact area between the rotating clamp 130 and the first clamp 110 and the second clamp 120 is larger than the direct contact area between the holding end 210 and the first clamp 110 and the second clamp 120, thereby further increasing the uniformity of force.

[0067] Please see Figure 8 This invention also provides a test method for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace. Based on the above-described test apparatus, the test method of this invention includes:

[0068] Step 1: Sample preparation

[0069] Clamping ends 210 are prepared at both ends of the working section 220 of the sample to ensure that the shape of the clamping ends 210 of the processed flat plate sample 200 matches the trapezoidal grooves of the first clamp 110 and the second clamp 120 in the test device.

[0070] Step 2: Assemble the test apparatus and sample:

[0071] Step 2-1: Place the two clamping ends 210 of the flat plate sample 200 into the first trapezoidal groove 111 and the second trapezoidal groove 121 respectively;

[0072] Step 2-2: Place rotating clamping blocks 130 on both sides of the first trapezoidal groove 111 and the second trapezoidal groove 121 respectively, that is, the rotating clamping blocks 130 are located in the first arc groove 112 and the second arc groove 122;

[0073] Steps 2-3: Adjust the position of the clamps so that the rotating clamp 130 is in close contact with the wall of the arc groove, and the sample clamping end 210 is in close contact with the wall of the trapezoidal groove and the two rotating clamps 130 on the left and right. At the same time, ensure that the rotating clamp 130 can rotate around the center during the clamping process to automatically adjust the angle and maintain uniform force, thereby achieving self-adjustment of force during loading, avoiding single-point force and stress concentration. Then, the flat plate sample 200 is firmly positioned by bolts or clamps.

[0074] Step 3: Install the assembled testing device onto the testing machine:

[0075] The outer ends of the first clamp 110 and the second clamp 120, namely the first connecting part 114 and the second connecting part 124, are respectively connected to the chuck of the testing machine so that the tensile load of the testing machine can be simultaneously transmitted to the upper and lower clamping ends 210 of the specimen.

[0076] Step 4: Apply load:

[0077] Start the testing machine and gradually increase the tensile load. Observe the deformation of the specimen during the loading process. During this process, the rotating clamp 130 can automatically adjust the clamping angle with the loading process, thereby ensuring that the force on both ends of the specimen is uniform and avoiding eccentricity or stress concentration caused by direct clamping.

[0078] Step 5, Testing and Recording:

[0079] During the process of the specimen being stretched to fracture, the tensile load-displacement curve is recorded, and the mechanical parameters such as the ultimate strength and elastic modulus of the specimen are determined.

[0080] This invention, through the combination of trapezoidal and arc-shaped grooves inside the fixture and the rotatable clamping block within the arc-shaped groove, enables the flat plate specimen to self-adjust during the tensile process, thereby ensuring uniform force distribution and preventing the fixture root from breaking first. Compared with the traditional direct clamping method, this invention not only improves the accuracy and reliability of test data but also effectively avoids the risk of the testing machine clamp being burned out under high-temperature conditions.

[0081] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A testing apparatus for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace, comprising a flat plate specimen (200), characterized in that, It also includes a first clamp (110), a second clamp (120), and a rotating clamp (130); The flat plate specimen (200) includes two holding ends (210) and a working section (220) located between them; The first clamp (110) includes a first groove portion (113) and a first connecting portion (114), wherein the first groove portion (113) has a groove on its side, which is composed of a first trapezoidal groove (111) and two first arc grooves (112) located on its left and right sides; The second clamp (120) includes a second groove (123) and a second connecting part (124), wherein the second groove (123) has a groove on its side, which is composed of a second trapezoidal groove (121) and two second arc grooves (122) located on its left and right sides; The rotating clamp (130) has an arc-shaped structure and consists of two sets of two sub-clamps that are symmetrical from left to right, and are respectively placed in two first arc grooves (112) and two second arc grooves (122); The first clamp 110 and the second clamp 120 have the same structure and are symmetrically arranged at both ends of the flat plate specimen (200). The first groove (113) and the second groove (123) respectively clamp the holding end (210) and the rotating clamp (130) of the flat plate specimen (200) to jointly clamp the flat plate specimen (200). The first connecting part (114) and the second connecting part (124) are directly connected to the loading end of the testing machine, so that the external tensile load is transmitted along the axial direction of the flat plate specimen (200).

2. The test apparatus for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace as described in claim 1, characterized in that, Both bearing ends (210) of the flat plate sample (200) are trapezoidal structures.

3. The test apparatus for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace as described in claim 1, characterized in that: The first groove (113) and the first connecting part (114) are coaxial cylindrical structures; the second groove (123) and the second connecting part (124) are coaxial cylindrical structures; the widths of the first groove (113) and the second groove (123) are the same and both are greater than the width of the flat plate sample (200).

4. The test apparatus for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace as described in claim 1, characterized in that, The first trapezoidal groove (111) has the same depth as the first circular arc groove (112), and the two sides of the first trapezoidal groove (111) coincide with the chords of the two first circular arc grooves (112); the second trapezoidal groove (121) has the same depth as the second circular arc groove (122), and the two sides of the second trapezoidal groove (121) coincide with the chords of the two second circular arc grooves (122).

5. The test apparatus for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace as described in claim 1, characterized in that, The two sets of rotating clamps (130) are arranged concentrically with the first arc groove (112) and the second arc groove (122), respectively, and are in contact with the left and right sides of the two holding ends (210) of the flat plate sample (200) placed in the first trapezoidal groove (111) and the second trapezoidal groove (121), respectively.

6. The test apparatus for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace as described in claim 5, characterized in that, The rotating clamp (130) can rotate freely and automatically adjust its angle during the clamping process to achieve force self-adjustment, thereby ensuring that the flat plate sample is subjected to uniform force during tensile loading.

7. The test apparatus for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace as described in claim 1, characterized in that, The contact area between the rotating clamp (130) and the first clamp (110) and the second clamp (120) is larger than the direct contact area between the clamping end (210) and the first clamp (110) and the second clamp (120), thereby increasing the uniformity of force distribution.

8. The test apparatus for achieving uniform tensile loading of a flat plate specimen in a high-temperature furnace as described in claim 1, characterized in that, The first trapezoidal groove (111) and the second trapezoidal groove (121) are planar groove structures, which respectively cooperate with the two holding ends (210) of the flat plate sample (200); the first arc groove (112) and the second arc groove (122) are respectively cooperate with the rotating clamp (130).

9. A test method based on the test apparatus according to any one of claims 1-8, characterized in that, Specifically, it includes: Step 1: Sample preparation Clamping ends (210) are prepared at both ends of the working section (220) of the sample to ensure that the shape of the clamping end (210) of the processed flat sample (200) matches the trapezoidal groove of the first clamp (110) and the second clamp (120) in the test device. Step 2: Assemble the test apparatus and sample: Step 2-1: Place the two clamping ends (210) of the flat plate sample (200) into the first trapezoidal groove (111) and the second trapezoidal groove (121) respectively; Step 2-2: Place rotating clamping blocks (130) on both sides of the first trapezoidal groove (111) and the second trapezoidal groove (121), that is, the rotating clamping blocks (130) are located in the first circular arc groove (112) and the second circular arc groove (122); Steps 2-3: Adjust the position of the clamps so that the rotating clamp (130) fits tightly against the wall of the arc groove, and the sample clamping end (210) fits tightly against the wall of the trapezoidal groove and the two rotating clamps (130) on the left and right. At the same time, ensure that the rotating clamp (130) can rotate around the center during the clamping process to automatically adjust the angle and maintain uniform force, so as to achieve self-adjustment of force during loading, avoid single-point force and stress concentration, and then firmly position the flat plate sample (200) by bolts or clamps. Step 3: Install the assembled testing device onto the testing machine: The outer ends of the first clamp (110) and the second clamp (120), namely the first connecting part (114) and the second connecting part (124), are respectively connected to the chuck of the testing machine so that the tensile load of the testing machine can be simultaneously transmitted to the upper and lower clamping ends (210) of the specimen. Step 4: Apply load: Start the testing machine and gradually increase the tensile load. Observe the deformation of the specimen during the loading process. During this process, the rotating clamp (130) can automatically adjust the clamping angle with the loading process, thereby ensuring that the two ends of the specimen are subjected to uniform force and avoiding eccentricity or stress concentration caused by direct clamping. Step 5, Testing and Recording: During the process of the specimen being stretched to fracture, the tensile load-displacement curve is recorded, and the mechanical parameters such as the ultimate strength and elastic modulus of the specimen are determined.

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