Carbon fiber rod tension-bending-torsion coupling test device and method for universal testing machine

Abstract

The invention provides a carbon fiber rod tension-bending-torsion coupling test device and method for a universal testing machine. The device is suitable for mechanical tests of tension-bending coupling, tension-torsion coupling and tension-bending-torsion coupling. The device comprises two stretching, bending and twisting clamping ends, a screw rod assembly and a support, the screw rod assembly is composed of a first transverse screw rod, a second transverse screw rod and a longitudinal screw rod, and the distance between the transverse screw rods and the position of a top block in the arch can be accurately controlled. The device has the advantages of comprehensiveness, accuracy, flexibility, convenience, stability, safety and the like, can comprehensively simulate complex stress conditions in actual work, improves the accuracy of test data, adapts to carbon fiber rods with different lengths and spans, simplifies the operation process, reduces test errors, ensures safe and reliable connection, and is suitable for popularization and application. And an innovative solution is provided for complex stress analysis of the carbon fiber rod.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical property testing, and in particular to a carbon fiber rod tension-bending-torsion coupling testing device and method for a universal testing machine. Background Art

[0002] With the continuous development and consumption of traditional land resources, the development and utilization of new water energy has gradually become a new trend in the energy field, including wind energy, solar energy, wave energy, tidal energy and other forms. In order to effectively develop these new water energy, various floating structures have emerged. In order to ensure that these floating structures are not affected or damaged by environmental loads such as wind, waves, and water flow when operating on the water, the mooring system has become an indispensable component. The mooring system connects the floating structure at one end and fixes the other end to the underwater anchor foundation, thereby ensuring the safety and smooth operation of the floating structure.

[0003] Carbon fiber has been widely used in many fields due to its excellent mechanical properties, including carbon fiber cables in mooring systems. Due to the variability of environmental loads, the force conditions borne by carbon fiber cables are extremely complex. In order to ensure their safe and stable operation, the force analysis of each carbon fiber rod in the cable is crucial. Tension, bending, and torsion are basic forms of force, which are the basis for more complex force analysis. Traditional universal testing machines mainly provide tensile and compression loading modes. In order to meet the needs of complex force tests, we have designed a new type of test device. This device can be combined with a universal testing machine to realize tension-bending, tension-torsion, and tension-bending-torsion mechanical coupling tests, thereby performing a comprehensive and complex force analysis of carbon fiber rods. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of this, the present invention provides a carbon fiber rod tension-bending-torsion coupling test device and method for a universal testing machine to solve the technical problem that the test method of the existing universal testing machine has limitations.

[0006] (II) Technical solution

[0007] The present invention provides a carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine, which is applied to tension-bending coupling test, tension-torsion coupling test and tension-bending-torsion coupling test, and comprises: two tension-bending-torsion clamping ends, a screw assembly and a bracket;

[0008] The screw assembly comprises: a first transverse screw, a second transverse screw and a longitudinal screw;

[0009] The first transverse screw and the second transverse screw are assembled and fixed on the longitudinal screw, the longitudinal screw is installed in the bracket and can move vertically along the bracket, and one of the tension, bending and twisting clamping ends is fixedly connected to the end of the first transverse screw;

[0010] The distance between the first horizontal screw and the second horizontal screw is equal to half of the initial span of the carbon fiber rod to be tested, the end of the second horizontal screw is located in the arch of the carbon fiber rod to be tested, the two tension, bending and torsion clamping ends are used to connect with the clamping ends of the universal testing machine, and the anchors at both ends of the carbon fiber rod to be tested are respectively installed on the two tension, bending and torsion clamping ends.

[0011] Furthermore, the tension, bending and torsion clamping end includes: a carbon fiber rod anchor connection end, an end connection seat and a universal testing machine clamping end;

[0012] The end connection seat is provided with an assembly through hole, a screw connection threaded hole and a torsion fixing groove;

[0013] The carbon fiber rod anchor connection end comprises: a screw portion, a torsion fixing block and an oblique threaded hole portion;

[0014] The universal testing machine clamping end head comprises: a rectangular clamping block and a threaded portion;

[0015] The screw rod portion passes through the assembly through hole and is connected to the threaded portion, so that the carbon fiber rod anchor connection end, the end connection seat and the universal testing machine clamping end are assembled into one, and the torsion fixing block is located in the torsion fixing groove;

[0016] The anchor at the end of the carbon fiber rod to be tested is connected to the carbon fiber rod anchor connection end through the oblique threaded hole, the end of the first transverse screw is connected to the end connection seat through the screw connection threaded hole, and the rectangular clamping block is connected to the clamping end of the universal testing machine.

[0017] Furthermore, the bracket includes: a base portion and a frame body portion; the frame body portion is fixedly mounted on the base portion; a slideway is arranged on the frame body portion, and the longitudinal screw is located in the slideway and can move along the slideway.

[0018] Furthermore, the screw assembly also includes: an arch top block; the arch top block is provided with an arch groove and a second cross screw threaded hole; the arch top block is connected to the second cross screw through the second cross screw threaded hole, so that the arch center of the carbon fiber rod to be tested is located in the arch groove.

[0019] Furthermore, the bracket also includes: a first sliding block for fixing the first transverse screw and the longitudinal screw, and the first sliding block is located outside the bracket body.

[0020] Furthermore, the bracket also includes: a second sliding block for fixing the second transverse screw and the longitudinal screw, and the second sliding block is located in the slideway and can move along the slideway.

[0021] Furthermore, scale lines are arranged on the frame body.

[0022] The carbon fiber rod tension-bending-torsion coupling test method uses a universal testing machine and the carbon fiber rod tension-bending-torsion coupling test device for the universal testing machine to test the carbon fiber rod to be tested.

[0023] Further, including:

[0024] S1. Anchor the two ends of the carbon fiber rod to be tested with threaded anchors for later use;

[0025] S2, install the carbon fiber rod to be tested between two tension, bending and torsion clamping ends through an anchor;

[0026] S3. Clamp the upper and lower clamping ends of the universal testing machine onto the two tension, bending and torsion clamping ends, and adjust to the required span;

[0027] S4, adjusting the spacing between the first cross screw and the second cross screw to be equal to half of the initial span of the carbon fiber rod to be tested;

[0028] S5, fixing and connecting the first transverse screw to the upper tension-bending-torsion clamping end;

[0029] S6, adjusting the second transverse screw to adjust the arch top block to the arch middle position of the carbon fiber rod to be tested, so that the arch middle of the carbon fiber rod to be tested is located in the arch groove;

[0030] S7. Start the universal testing machine.

[0031] (III) Beneficial effects

[0032] The above technical solution of the present invention has the following advantages:

[0033] Comprehensiveness: The device can perform mechanical tests on carbon fiber rods, including tension-bending coupling, tension-torsion coupling, and tension-bending-torsion coupling, to fully simulate the complex stress conditions in actual work, thereby more accurately evaluating the performance of carbon fiber rods.

[0034] Accuracy: By precisely controlling the distance between the first cross screw and the second cross screw, as well as the position of the top block in the arch, the consistency of the initial span and the arch position of the carbon fiber rod to be tested in the test is ensured, thereby improving the accuracy of the test data.

[0035] Flexibility: The design of the device allows the adjustment of the screw assembly to accommodate carbon fiber rods of different lengths and spans, making the test device widely applicable.

[0036] Convenience: Through the preset slides and scale lines, users can adjust and position the test device conveniently and quickly, which greatly simplifies the operation process and improves test efficiency.

[0037] Stability: The design of two tension, bending and torsion clamping ends ensures that the carbon fiber rod to be tested is firmly fixed in the predetermined position during the test, reducing the test error caused by unstable clamping.

[0038] Safety: The special design of the carbon fiber rod anchor connection end and the universal testing machine clamping end ensures that the connection between the carbon fiber rod to be tested and the test device is safe and reliable when complex forces are applied.

[0039] Innovation: The test device and method of the present invention provide a new solution for the complex force analysis of carbon fiber rods, filling the gap of traditional universal testing machines in complex mechanical coupling tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings of the present invention are provided for illustrative purposes only, and the proportions and quantities of the components in the drawings may not necessarily be consistent with the actual products.

[0041] Figure 1 1 is a schematic structural diagram of a carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine in an embodiment of the present invention;

[0042] Figure 2 2 is a schematic diagram of the structure of the tension, bending and twisting clamping end in an embodiment of the present invention;

[0043] Figure 3 is a schematic diagram of the structure of the terminal connection base in an embodiment of the present invention;

[0044] Figure 4 This is a schematic structural diagram of a connecting end of a carbon fiber rod anchor in an embodiment of the present invention;

[0045] Figure 5 It is a structural schematic diagram of the clamping end of the universal testing machine in an embodiment of the present invention;

[0046] Figure 6 Schematic diagram of torsion angle in an embodiment of the present invention;

[0047] Figure 7 It is a structural schematic diagram of a screw assembly and a bracket in an embodiment of the present invention;

[0048] Figure 8 In the embodiment of the present invention Figure 7 A schematic diagram of the interior of A;

[0049] Fig. 9 Schematic diagram of the structure of the top block in the arch in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] See also Figure 1-9 As shown, in order to effectively carry out tensile, bending and torsional coupling mechanical tests of carbon fiber rods on a universal testing machine, the present invention provides a carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine, which is applied to tension-bending coupling tests, tension-torsion coupling tests and tension-bending-torsion coupling tests. This device not only improves the test accuracy, but also enhances the reliability and repeatability of the experimental results.

[0052] The carbon fiber rod tension-bending-torsion coupling test device of the present application specifically comprises: a tension-bending-torsion clamping end 1, a screw rod assembly 2 and a bracket 3, and the number of the tension-bending-torsion clamping end 1 is two.

[0053] The tension-bending-torsion clamping end 1 is used to fix the bending angle and torsion angle of the carbon fiber rod to be tested. When the universal testing machine applies tension, the tension-bending-torsion coupling test effect can be achieved. The two tension-bending-torsion clamping ends 1 are used to connect with the clamping end of the universal testing machine. The anchors at both ends of the carbon fiber rod to be tested are respectively installed on the two tension-bending-torsion clamping ends 1, so that the carbon fiber rod to be tested is fixed between the two tension-bending-torsion clamping ends 1 to ensure the stable installation of both ends of the carbon fiber rod to be tested, ensure the accuracy of the applied force, reduce the influence of external factors on the test results, and thus improve the credibility of the test data.

[0054] The tension, bending and torsion clamping end 1 comprises: a carbon fiber rod anchor connecting end 5, an end connecting seat 4 and a universal testing machine clamping end 6.

[0055] The end connection seat 4 is provided with an assembly through hole 8, a screw connection threaded hole 9 and a torsion fixing groove 7.

[0056] The carbon fiber rod anchor connection end 5 includes: a screw portion 10, a torsion fixing block 11 and an oblique threaded hole portion 12. The depth and diameter of the oblique threaded hole portion 12 match the anchor thread of the end of the carbon fiber rod to be tested, and the angle between its axis and the vertical direction depends on the bending angle of the test design. When this angle is 0°, it means that only the tension-torsion coupling test is performed.

[0057] The function of the oblique threaded hole portion 12 is to fix the bending angle of the carbon fiber rod to be tested during the test. The design of the oblique threaded hole portion 12 allows the anchor thread of the carbon fiber rod to be accurately matched, and the angle between its axis and the vertical direction can be flexibly adjusted according to the test requirements, ensuring the controllability of the bending angle.

[0058] The torsion fixing block 11 on the carbon fiber rod anchor connection end 5 is movably connected to the torsion fixing groove 7 in the end connection seat 4 to fix the torsion angle α of the test design. When the torsion angle α is 0°, the tension-bending coupling test is performed. This design allows precise control of the torsion angle, maintaining high accuracy even under complex conditions, and significantly improves the consistency of the test results.

[0059] The clamping end 6 of the universal testing machine includes: a rectangular clamping block 14 and a threaded portion 13. The screw portion 10 of the carbon fiber rod anchor connection end 5 is adapted to the threaded portion 13 of the clamping end of the universal testing machine, and the screw portion 10 passes through the assembly through hole 8 and is threadedly connected to the threaded portion 13, so that the carbon fiber rod anchor connection end 5, the end connection seat 4 and the clamping end 6 of the universal testing machine are assembled into one, and the torsion fixing block 11 is located in the torsion fixing groove 7. The rectangular clamping block 14 is connected to the clamping end of the universal testing machine, and by adapting the screw portion 10 and the threaded portion 13, the stability of the overall structure of the device is ensured, while simplifying the assembly process and improving work efficiency.

[0060] The anchor at the end of the carbon fiber rod to be tested is connected to the carbon fiber rod anchor connection end 5 through the oblique threaded hole 12; one of the tension, bending and torsion clamping ends 1 is fixedly connected to the end of the first horizontal screw 16. Specifically, the end of the first horizontal screw 16 is connected to the end connection seat 4 through the screw connection threaded hole 9 to ensure the stability of the bracket 3 during the test. The rectangular clamping block 14 is connected to the clamping end of the universal testing machine. The tension, bending and torsion clamping end 1 is used to fix the bending angle and torsion angle of the carbon fiber rod. When the universal testing machine applies tension to the carbon fiber rod to be tested, the tension, bending and torsion coupling test effect can be achieved. In order to ensure that the arch height and bending angle of the carbon fiber rod to be tested do not change during the test, the tension, bending and torsion clamping end 1 needs to be used in conjunction with the bracket 3 and the screw assembly 2.

[0061] The screw assembly 2 includes a first transverse screw 16, a second transverse screw 17 and a longitudinal screw 15; the first transverse screw 16 and the second transverse screw 17 are assembled and fixed on the longitudinal screw 15; the longitudinal screw 15 is installed in the bracket 3 and can move vertically along the bracket 3. The distance between the first transverse screw 16 and the second transverse screw 17 is equal to half of the initial span of the carbon fiber rod to be tested, and the end of the second transverse screw 17 is located in the arch of the carbon fiber rod to be tested.

[0062] Preferably, an arch top block 21 is provided on the second transverse screw 17, and the arch top block 21 is provided with an arch groove 26 and a second transverse screw threaded hole 25. The arch top block 21 is threadedly connected to the second transverse screw 17 through the second transverse screw threaded hole 25, so that the arch center of the carbon fiber rod to be tested is located in the arch groove 26, so as to ensure that the arch height and bending angle of the carbon fiber rod to be tested will not change during the test. When the universal testing machine is in the stretching process, the tension, bending and torsion clamping end 1 located above will move upward with the clamping end above the universal testing machine, and at this time, the arch top block 21 will move upward with the first transverse screw 16 and the second slider 22 in the slideway 20, so as to ensure that the arch top block 21 is always located near the arch center of the carbon fiber rod to be tested during the test.

[0063] The screw assembly 2 composed of the first transverse screw 16, the second transverse screw 17 and the longitudinal screw 15 ensures that the arch height and bending angle of the carbon fiber rod to be tested remain unchanged during the test, greatly improving the accuracy and repeatability of the measurement. In particular, the setting of the arch top block 21 further ensures the position stability of the carbon fiber rod when it is deformed by force, avoiding errors in the measurement data caused by position offset.

[0064] It should be noted that, since the clamping end at the bottom of the universal testing machine is fixed, when the tension is applied, only the clamping end at the top moves upward, so the displacement in the arch of the carbon fiber rod to be tested is equal to half of the displacement of the clamping end at the top of the universal testing machine. Since the first horizontal screw 16, the second horizontal screw 17 and the longitudinal screw 15 are fixedly connected, the spacing between the first horizontal screw 16 and the second horizontal screw 17 is always equal to half of the initial span of the carbon fiber rod to be tested during the entire test process. In addition, the length of the carbon fiber rod to be tested is short, and the elongation of the carbon fiber rod to be tested is very small during the process from applying the tension to breaking, so it can be assumed that the top block 21 in the arch is always located in the arch of the carbon fiber rod to be tested during the test.

[0065] In order to ensure that the arch height / bending angle of the carbon fiber rod does not change during the test, the tension, bending and torsion clamping end 1 needs to be used in conjunction with the bracket 3. Specifically, the bracket 3 includes: a base portion 19 and a frame body portion 18; the frame body portion 18 is fixedly mounted on the base portion 19. A slideway 20 is provided on the frame body portion 18, and the longitudinal screw 15 is located in the slideway 20 and can move up and down along the slideway 20, ensuring the dynamic balance of the entire system. The frame body portion 18 is also marked with scale lines 24, which are used to accurately adjust the spacing between the first horizontal screw 16 and the second horizontal screw 17 to make it equal to half of the initial span of the carbon fiber rod to be tested. The addition of scale lines 24 allows the operator to more accurately adjust and monitor the position of each component, which helps to achieve more precise test control.

[0066] The bracket 3 further includes: a first slider 23 for fixing the first transverse screw 16 and the longitudinal screw 15, and a second slider 22 for fixing the second transverse screw 17 and the longitudinal screw 15. The first slider 23 is located outside the frame body 18, specifically above the frame body 18, and the second slider 22 is located in the slideway 20. When the first transverse screw 16 moves, the second slider 22 moves along the slideway 20, thereby driving the longitudinal screw 15 to move along the slideway 20. The design of the first slider 23 and the second slider 22 ensures a rigid connection between the transverse screw and the longitudinal screw, and can maintain structural stability even when subjected to a large external force, thereby ensuring the safety and reliability of the test.

[0067] Through the application of the above-mentioned design and technical means, the carbon fiber rod tension-bending-torsion coupling test device provided by the present invention realizes efficient and accurate testing of the mechanical properties of carbon fiber rods, providing strong support for material science research.

[0068] The present invention also includes a carbon fiber rod tension-bending-torsion coupling test method, which uses a universal testing machine and the carbon fiber rod tension-bending-torsion coupling test device for the universal testing machine to test the carbon fiber rod to be tested.

[0069] The carbon fiber rod tension-bending-torsion coupling test method specifically includes the following steps:

[0070] S1. Anchor the two ends of the carbon fiber rod to be tested with threaded anchors for later use;

[0071] S2, install the carbon fiber rod to be tested between the two tension, bending and torsion clamping ends 1 through an anchor;

[0072] S3, clamp the upper and lower clamping ends of the universal testing machine on the two tension, bending and torsion clamping ends 1, and adjust to the required span;

[0073] S4, adjusting the spacing between the first cross screw 16 and the second cross screw 17 to be equal to half of the initial span of the carbon fiber rod to be tested, and using the scale line 24 for precise positioning;

[0074] S5, the first transverse screw 16 is fixedly connected to the tension, bending and twisting clamping end 1 located above to ensure a firm and reliable connection;

[0075] S6, adjusting the second transverse screw 17 to adjust the arch top block 21 to the arch middle position of the carbon fiber rod to be tested, so that the arch middle of the carbon fiber rod to be tested is against the arch groove 26, so as to maintain the stability and bending angle of the carbon fiber rod unchanged during the test;

[0076] S7. Start the universal testing machine, apply tensile, bending and torsional coupling loads step by step according to the predetermined program, and start the tension-bending-torsion coupling mechanical test.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that not every embodiment contains only one independent technical solution. In the absence of a conflict of solutions, the various technical features mentioned in each embodiment can be combined in any manner to form other implementation methods that can be understood by those skilled in the art.

[0078] In addition, without departing from the scope of the present invention, the technical solutions described in the aforementioned embodiments may be modified, or some of the technical features may be replaced by equivalents, without causing the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine, characterized in that: Applicable to tension-bending coupling test, tension-torsion coupling test and tension-bending-torsion coupling test, including: two tension-bending-torsion clamping ends, screw assembly and bracket; The screw assembly comprises: a first transverse screw, a second transverse screw and a longitudinal screw; The first transverse screw and the second transverse screw are assembled and fixed on the longitudinal screw, the longitudinal screw is installed in the bracket and can move vertically along the bracket, and one of the tension, bending and twisting clamping ends is fixedly connected to the end of the first transverse screw; The distance between the first horizontal screw and the second horizontal screw is equal to half of the initial span of the carbon fiber rod to be tested, the end of the second horizontal screw is located in the arch of the carbon fiber rod to be tested, the two tension, bending and torsion clamping ends are used to connect with the clamping ends of the universal testing machine, and the anchors at both ends of the carbon fiber rod to be tested are respectively installed on the two tension, bending and torsion clamping ends.

2. A carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine as claimed in claim 1, characterized in that: The tension, bending and torsion clamping end includes: a carbon fiber rod anchor connection end, an end connection seat and a universal testing machine clamping end; The end connection seat is provided with an assembly through hole, a screw connection threaded hole and a torsion fixing groove; The carbon fiber rod anchor connection end comprises: a screw portion, a torsion fixing block and an oblique threaded hole portion; The universal testing machine clamping end head comprises: a rectangular clamping block and a threaded portion; The screw rod portion passes through the assembly through hole and is connected to the threaded portion, so that the carbon fiber rod anchor connection end, the end connection seat and the universal testing machine clamping end are assembled into one, and the torsion fixing block is located in the torsion fixing groove; The anchor at the end of the carbon fiber rod to be tested is connected to the carbon fiber rod anchor connection end through the oblique threaded hole, the end of the first transverse screw is connected to the end connection seat through the screw connection threaded hole, and the rectangular clamping block is connected to the clamping end of the universal testing machine.

3. A carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine as claimed in claim 2, characterized in that: The bracket comprises: a base part and a frame body part; the frame body part is fixedly installed on the base part; a slideway is arranged on the frame body part, and the longitudinal screw rod is located in the slideway and can move along the slideway.

4. A carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine as claimed in claim 3, characterized in that: The screw assembly further comprises: an arch top block; the arch top block is provided with an arch groove and a second transverse screw threaded hole; the arch top block is connected to the second transverse screw through the second transverse screw threaded hole, so that the arch center of the carbon fiber rod to be tested is located in the arch groove.

5. A carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine as claimed in claim 3, characterized in that: The bracket further comprises: a first sliding block for fixing the first transverse screw rod and the longitudinal screw rod, wherein the first sliding block is located outside the bracket body.

6. A carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine as claimed in claim 3, characterized in that: The bracket further comprises: a second sliding block for fixing the second transverse screw rod and the longitudinal screw rod, wherein the second sliding block is located in the slideway and can move along the slideway.

7. A carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine as claimed in claim 3, characterized in that: Scale lines are arranged on the frame body.

8. Carbon fiber rod tension-bending-torsion coupling test method, characterized in that: The carbon fiber rod to be tested is tested using a universal testing machine and the carbon fiber rod tension-bending-torsion coupling test device for a universal testing machine as described in any one of claims 1 to 7.

9. The carbon fiber rod tension-bending-torsion coupling test method according to claim 8, characterized in that: include: S1. Anchor the two ends of the carbon fiber rod to be tested with threaded anchors for later use; S2, install the carbon fiber rod to be tested between two tension, bending and torsion clamping ends through an anchor; S3. Clamp the upper and lower clamping ends of the universal testing machine onto the two tension, bending and torsion clamping ends, and adjust to the required span; S4, adjusting the spacing between the first cross screw and the second cross screw to be equal to half of the initial span of the carbon fiber rod to be tested; S5, fixing and connecting the first transverse screw to the upper tension-bending-torsion clamping end; S6, adjusting the second transverse screw to adjust the arch top block to the arch middle position of the carbon fiber rod to be tested, so that the arch middle of the carbon fiber rod to be tested is located in the arch groove; S7. Start the universal testing machine.

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