A kind of dynamic and static tensile test fixture and test method suitable for cable
By designing a dynamic and static tensile test fixture suitable for cables, and adopting a T-shaped frustum, sleeve and cone structure, the inner layer of the cable core is protected from damage, and accurate testing of the cable is achieved. This solves the problem that existing fixtures cannot stably clamp flexible connections and is suitable for static and dynamic tensile tests.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUNAN UNIV OF SCI & TECH
- Filing Date
- 2023-06-07
- Publication Date
- 2026-07-21
AI Technical Summary
Existing clamps cannot stably hold flexible cables, especially synthetic fiber cables and steel wire ropes, and cannot simulate their stress conditions in dynamic and static tensile mechanical tests, which may also damage the internal battery cells.
The fixture, consisting of a T-shaped truncated cone, sleeve, cone, and threaded locking components, protects the inner battery core of the cable from damage through the stepped hole of the sleeve and the design of the cone, applying force only to the outer layer. Dynamic and static tensile tests are conducted in conjunction with a tensile testing machine and a Hopkinson rod device.
It enables precise testing of cables, protecting the inner battery cells from damage, and is applicable to both static and dynamic tensile tests, reducing experimental costs and improving the accuracy of test results.
Smart Images
Figure CN116558947B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of cable tensile testing technology, and in particular relates to a dynamic and static tensile testing fixture and testing method suitable for cables. Background Technology
[0002] Tensile testing equipment (such as the Hopkinson bar device and tensile testing machines) plays a crucial role in material specimen testing as a commonly used dynamic and static mechanical property testing device, and is widely used in the dynamic and static tensile mechanical testing of metals, rocks, concrete, and composite materials. For tensile testing machines, the fixing connection method mostly uses built-in clamping clamps; while the fixing connection method of the Hopkinson bar device generally uses threaded connections, adhesive connections, snap-fit connections, and flat plate connections. Both types of tensile specimens are mostly cylindrical or plate-shaped specimens.
[0003] The clamping test procedure is generally as follows: the clamping sections at both ends of the specimen are installed and fixed at both ends of the tensile testing device (such as between the incident rod and the transmission rod of a Hopkinson test device, or between the two jaws of a tensile testing machine) using the methods mentioned above, and then the tensile test is performed. However, the following problems exist: 1. Existing cylindrical and plate-shaped specimens are suitable for rigid connections such as metals or concrete, but for large-sized specimens with helical flexible connections such as synthetic fiber cables and steel wire ropes, whose core layer is an optical fiber core and the outer layer is a multi-layer steel wire armor, it is necessary to understand the mechanical properties of such specimens under dynamic and static tension. Using only cylindrical and plate-shaped specimens may not be suitable, and they cannot be machined or welded like the specimens mentioned above. Therefore, conventional clamps are not suitable for the above-mentioned flexible connections; 2. Currently, clamps for such flexible connections are mainly focused on millimeter-level material connections such as wires and threads, which cannot fully simulate the stress conditions of the entire strand or even the cable. Therefore, in the process of dynamic and static tensile mechanical testing, there is an urgent need for a complete set of flexible connection clamps that can stably clamp the strands or even the cable without slippage and without damaging the inside of the cable. Summary of the Invention
[0004] To solve the above-mentioned technical problems, the present invention provides a simple structure, easy operation, and a dynamic and static tensile test fixture and test method for cables that can restore the stress state of the cable to the greatest extent and apply force only to the outer layer without causing clamping damage or tensile failure to the inner battery core.
[0005] The technical solution adopted in this invention is: a dynamic and static tensile test fixture for cables, comprising a T-shaped frustum, a sleeve, a cone, and a threaded locking component; the central hole of the sleeve is a stepped hole, and the two ends of the central hole of the sleeve are threaded hole I and threaded hole II, respectively, the major diameter of threaded hole II is larger than the major diameter of threaded hole I, and the middle part of the central hole of the sleeve is a conical aperture; a through hole is provided at the center of the T-shaped frustum, and the T-shaped frustum is screwed to threaded hole I; a cone is provided inside the conical aperture, the cone is coaxial with the conical aperture, and a through hole for the cable core to pass through is provided at the center of the cone; the threaded locking component is screwed to threaded hole II and is used to press the cone.
[0006] In the above-mentioned dynamic and static tensile test fixture for cables, a gasket is provided between the threaded locking member and the cone.
[0007] In the above-mentioned dynamic and static tensile test fixture for cables, the T-shaped frustum is provided with an annular flange at the end facing away from the threaded hole II.
[0008] A method for dynamic and static tensile testing of cables using the aforementioned dynamic and static tensile testing fixture is described in detail below: 1) Clamp the specimen at both ends using two dynamic and static tensile test fixtures suitable for cables; 2) Static Tension: Two threaded locking parts of dynamic and static tensile testing fixtures suitable for cables are screwed to the two tie rods of the tensile testing machine, respectively. The two tie rods are coaxial, one tie rod is fixed, and the other tie rod is connected to the power mechanism of the tensile testing machine. A force sensor is installed on each tie rod, and the force sensor is electrically connected to the computer. A displacement extensometer is installed on the specimen and is electrically connected to the computer. The computer and tensile testing machine are started, so that the specimen is tensioned but not stretched. Then, gauge lines are marked on the surface of the specimen, and then the tensile testing machine stretches the specimen. At the same time, the test data is acquired through the force sensor and displacement extensometer and transmitted to the computer. Dynamic Tension: The threaded locking parts of two dynamic and static tensile test fixtures suitable for cables are screwed to the opposite ends of the incident rod and the transmission rod of the Hopkinson tension bar device, respectively; the incident rod and the transmission rod are coaxial; the incident rod passes through the barrel and the bullet, the bullet is installed inside the barrel, and the part of the incident rod inside the barrel is a stepped shaft; a strain gauge is installed on the incident rod and the transmission rod, respectively, and the strain gauge is electrically connected to a Wheatstone bridge, the Wheatstone bridge is electrically connected to an ultra-strain dynamic meter, the ultra-strain dynamic meter is electrically connected to a sampling card, and the sampling card is electrically connected to a computer; the computer and the Hopkinson tension bar device are turned on, and the bullet is fired to impact the shoulder of the incident rod; the tensile wave signal is amplified by the strain gauge and the ultra-dynamic strain meter, the data is collected by the acquisition card, and the original dynamic tensile data is obtained by the computer output; 3) Repeat step 2) multiple times; the loading rate will be different for each two repetitions.
[0009] In the above-mentioned dynamic and static tensile test method applicable to cables, the specific operation of step 1) is as follows: 1.1) Unscrew the T-shaped frustum, then unscrew the threaded locking part from the sleeve, and remove the inner washer and the cone from the sleeve; 1.2) Insert the two T-shaped frustums into the specimen from both ends. 1.3) Insert the outer layer of one end of the specimen into the inner end of the sleeve from the upper end of the sleeve and extend it out from the other end of the sleeve. Then, insert the center hole of the cone into the battery cell of the specimen. Push the cone until the battery cell is completely inserted and the outer surface of the cone is in close contact with the outer layer of the specimen to form a conical umbrella shape. At this time, screw the T-shaped frustum on from the threaded hole I of the sleeve but do not lock it. Then, place the cone into the sleeve, put in the inner gasket, and then tighten the threaded locking part with the threaded hole II of the sleeve until the outer layer of the cable sample is pressed against the inclined surface inside the sleeve. Finally, lock the T-shaped frustum. 1.4) Repeat step 1.3) and clamp the other end of the specimen through another dynamic and static tensile test fixture suitable for cables.
[0010] Compared with the prior art, the beneficial effects of the present invention are: The dynamic and static tensile testing fixture for cables of this invention has a simple structure, which can directly clamp flexible spiral-shaped cables without disassembling the entire cable specimen. It can restore the stress state of the cable to the greatest extent, and has a central retaining hole, which applies force only to the outer layer, without causing clamping damage or tensile failure to non-stressed components such as the inner layer of the battery core; thus, the test results are more accurate. The dynamic and static tensile testing fixture for cables of this invention can be used to conduct both static tensile tests and Hopkinson bar tests for dynamic tensile testing. The dynamic and static tensile testing fixture for cables of this invention reduces the auxiliary operation time of traditional adhesive-bonded specimens while ensuring the accuracy of the experimental process; it can also be repeatedly disassembled and reused, has strong versatility, and reduces experimental costs. Attached Figure Description
[0011] Figure 1 This is a schematic diagram of the structure of the dynamic and static tensile testing fixture for cables of the present invention.
[0012] Figure 2 yes Figure 1 Sectional view of AA.
[0013] Figure 3 This is a schematic diagram of the installation of the dynamic and static tensile testing fixture for cables according to the present invention.
[0014] Figure 4 This is a schematic diagram of the structure during the dynamic tensile test of the present invention.
[0015] Figure 5 This is a schematic diagram of the structure during the static tensile test of the present invention.
[0016] In the figure: 1-Specimen, 2-T-shaped frustum, 3-Sleeve, 4-Frustum, 5-Shim, 6-Threaded locking piece, 7-Upper washer, 8-Cannon barrel, 9-Bullet, 10-Strain gauge, 11-Incident rod, 12-Transmission rod, 13-Pull rod, 14-Pull rod, 15-Force sensor, 16-Displacement extensometer. Detailed Implementation
[0017] The invention will now be further described with reference to the accompanying drawings.
[0018] like Figure 1-2 As shown, this invention relates to a fixture for dynamic and static tensile testing of cables, comprising a T-shaped frustum 2, a sleeve 3, a cone 4, and a threaded locking component 6. The sleeve 2 has a stepped central hole, with threaded holes I and II at its two ends. The major diameter of threaded hole II is larger than that of threaded hole I. The central hole of the sleeve 2 has a conical aperture. A through hole is located at the center of the T-shaped frustum 2, allowing the specimen to enter the sleeve 3. The T-shaped frustum 2 is screwed to threaded hole I. An annular flange is located at the end of the T-shaped frustum 2 facing away from threaded hole II. A cone 4 is located inside the conical aperture, coaxial with the conical aperture. A through hole for the cable core to pass through is located at the center of the cone 4. The threaded locking component 6 is screwed to threaded hole II and used to clamp the cone 4. A gasket 5 is provided between the threaded locking component 6 and the cone 4. The threaded locking component 6 includes a sleeve connection part and a tensile testing machine connection part. The sleeve connection part and the tensile testing machine connection part are cylindrical with external threads. The sleeve connection part and the tensile testing machine connection part are coaxial, and the diameter of the sleeve connection part is larger than the diameter of the tensile testing machine connection part.
[0019] The dynamic and static tensile testing fixture for cables of the present invention, when used to clamp test specimens, places the outer layer 101 of the specimen 1 within the conical aperture of the sleeve 3 and compresses it using the frustum 4. During the compression process of the frustum 4, the three strands of the outer layer 101 are gradually compressed together. Simultaneously, since the cable is a non-elastic material, the three strands of the outer layer 101 will rub against each other during compression, thus restricting the cable's slippage. The battery cell 102 of the test specimen 1 is placed within the central hole of the frustum 4 and is not subjected to compression, thus effectively protecting the battery cell 102.
[0020] The present invention provides a method for dynamic and static tensile testing of cables, the specific operation of which is as follows: 1) Clamp both ends of specimen 1 using two dynamic and static tensile test fixtures suitable for cables. The specific procedure is as follows: like Figure 3As shown, unscrew the T-shaped frustum 2, then unscrew the threaded locking part 6 from the sleeve 3, and remove the inner washer 5 and the cone 4 from the sleeve 3. During installation, first, insert the two T-shaped frustums 2 into the test piece 1 from both ends, then insert the outer layer 101 of one end of the test piece 1 into the inner end of the sleeve 3 from the upper end and extend it out from the other end of the sleeve 4, then insert the center hole of the cone 4 into the battery cell 102 of the test piece 1, push the cone 4 until the battery cell 102 is completely inserted and the outer surface of the cone 4 is tightly attached to the outer layer of the test piece 1, forming a conical umbrella shape. At this time, screw the T-shaped frustum 2 onto the threaded hole I of the sleeve 3 without locking it, then place the cone 4 into the sleeve 3, insert the inner washer 5, and then tighten the threaded locking part 6 into the threaded hole II of the sleeve 3 until the outer layer 101 of the cable sample is pressed against the inclined surface inside the sleeve 3, and finally lock the T-shaped frustum 2. Similarly, by pressing the other end of specimen 1 according to the same principle, dynamic and static tensile tests can be performed.
[0021] 2) Dynamic Tension: The threaded locking parts of two dynamic and static tensile testing fixtures suitable for cables are screwed to the opposite ends of the incident rod 11 and the transmission rod 12 of the Hopkinson rod device, respectively; the incident rod passes through the barrel and the bullet, with the bullet installed inside the barrel; the portion of the incident rod inside the barrel is a stepped shaft; a strain gauge is installed on each of the incident rod and the transmission rod, and the strain gauge is electrically connected to a Wheatstone bridge, which is then electrically connected to an ultrastrain dynamic meter, which is electrically connected to a sampling card, and the sampling card is electrically connected to a computer. For example... Figure 4 As shown, adjust the levelness and coaxiality of the incident rod 11 and the transmission rod 12, and check whether the strain gauges 10 on the incident rod 11 and the transmission rod 12 are firmly attached and whether the grounding wire is tightly connected. Before each test, ensure that the clamp and the tie rod are securely fastened. To eliminate waveform noise caused by gaps at the threaded connection between the clamp and the incident rod or transmission rod in dynamic and static tensile tests applicable to cables, use PTFE tape to couple and secure the threads. Tensile the incident rod 11 and the transmission rod 12 to keep the cable specimen 1 under tension; turn on the computer and the Hopkinson tie rod device, and fire a bullet to impact the shoulder of the incident rod; the tensile wave signal is amplified by the strain gauge and the ultra-dynamic strain gauge, and the data is collected by the acquisition card and output by the computer to obtain the original dynamic tensile data. After the test, unscrew the threaded locking part 6 and take out the specimen 1.
[0022] Static Tensile Testing: Two threaded locking fittings of dynamic and static tensile testing fixtures suitable for cables are screwed onto the two pull rods 13 and 14 of the tensile testing machine, respectively. The two pull rods 13 and 14 are coaxial, with pull rod 14 fixed and pull rod 13 connected to the power mechanism of the tensile testing machine. A force sensor 15 is installed on each of the two pull rods, and the force sensor 15 is electrically connected to the computer. A displacement extensometer 16 is installed on the specimen and is electrically connected to the computer. Figure 5As shown, the computer and tensile testing machine are started. The tensile testing machine moves the tie rod 13 upward, so that the cable sample 1 is tensioned but not stretched. The gauge length is marked on the locked sample 1. The tensile testing machine stretches the sample. At the same time, the test data is acquired by the force sensor 15 and the tensile extensometer 16 and transmitted to the computer.
[0023] The extension deformation under static tension is measured using a displacement tensile extensometer 16. Due to the clamping structure of the dynamic and static tensile test fixture suitable for cables, the cable specimen 1 is pulled tighter and tighter during the tensile process. Simultaneously, its T-shaped frustum 2 can provide some guidance to correct the poor alignment of the force direction caused by frequent use of the upper and lower parts of the tensile testing machine. Similarly, it can completely eliminate the damage to the cable core 102 caused by the dynamic and static tensile test fixture suitable for cables. After the test, the threaded locking part 6 is unscrewed, and the specimen 1 is removed.
[0024] 3) Repeat step 2) multiple times; the loading rate is different for each two loads; study the effect of different loading rates on the cable sample.
Claims
1. A fixture for dynamic and static tensile testing of cables, characterized in that: The device includes a T-shaped frustum, a sleeve, a cone, and a threaded locking component. The sleeve has a stepped central hole with threaded holes I and II at its two ends. The major diameter of threaded hole II is larger than that of threaded hole I. The central part of the sleeve's central hole is a conical aperture. The T-shaped frustum has a through hole at its center and is screwed to threaded hole I. The end of the T-shaped frustum facing away from threaded hole II has an annular flange. A cone is located inside the conical aperture, coaxial with the conical aperture. A through hole for the cable core to pass through is located at the center of the cone. The threaded locking component is screwed to threaded hole II to press the cone. A washer is provided between the threaded locking component and the cone. The threaded locking component includes a sleeve connecting part and a tensile testing machine connecting part. Both the sleeve connecting part and the tensile testing machine connecting part are cylindrical with external threads. They are coaxial, and the diameter of the sleeve connecting part is larger than that of the tensile testing machine connecting part.
2. A method for dynamic and static tensile testing of cables using the dynamic and static tensile testing fixture for cables as described in claim 1, characterized in that: The specific steps are as follows: 1) Clamp the specimen at both ends using two dynamic and static tensile test fixtures suitable for cables; 2) Static Tension: Two threaded locking parts of dynamic and static tensile testing fixtures suitable for cables are screwed to the two tie rods of the tensile testing machine, respectively. The two tie rods are coaxial, one tie rod is fixed, and the other tie rod is connected to the power mechanism of the tensile testing machine. A force sensor is installed on each tie rod, and the force sensor is electrically connected to the computer. A displacement extensometer is installed on the specimen and is electrically connected to the computer. The computer and tensile testing machine are started, so that the specimen is tensioned but not stretched. Then, gauge lines are marked on the surface of the specimen, and then the tensile testing machine stretches the specimen. At the same time, the test data is acquired through the force sensor and displacement extensometer and transmitted to the computer. Dynamic Tension: The threaded locking parts of two dynamic and static tensile test fixtures suitable for cables are screwed to the opposite ends of the incident rod and the transmission rod of the Hopkinson rod device, respectively; the incident rod and the transmission rod are coaxial; the incident rod passes through the barrel and the bullet, the bullet is installed inside the barrel, and the part of the incident rod inside the barrel is a stepped shaft; a strain gauge is installed on the incident rod and the transmission rod, respectively, and the strain gauge is electrically connected to a Wheatstone bridge, the Wheatstone bridge is electrically connected to an ultra-strain dynamic meter, the ultra-strain dynamic meter is electrically connected to a sampling card, and the sampling card is electrically connected to a computer; the computer and the Hopkinson rod device are turned on, and the bullet is fired to impact the shoulder of the incident rod; the tensile wave signal is amplified by the strain gauge and the ultra-dynamic strain meter, the data is collected by the acquisition card, and the original dynamic tensile data is obtained by the computer output; 3) Repeat step 2) multiple times; the loading rate will be different for each two repetitions.
3. The method for dynamic and static tensile testing of cables according to claim 2, characterized in that: The specific steps for step 1) are as follows: 1.1) Unscrew the T-shaped frustum, then unscrew the threaded locking part from the sleeve, and remove the inner washer and the cone from the sleeve; 1.2) Insert the two T-shaped frustums into the specimen from both ends; 1.3) Insert the outer layer of one end of the specimen into the inner end of the sleeve from the upper end of the sleeve and extend it out from the other end of the sleeve. Then, insert the center hole of the cone into the battery cell of the specimen. Push the cone until the battery cell is completely out and the outer surface of the cone is in close contact with the outer layer of the specimen to form a conical umbrella shape. At this time, screw the T-shaped frustum on from the threaded hole I of the sleeve but do not lock it. Then, place the cone into the sleeve, put in the inner gasket, and then tighten the threaded locking part to the threaded hole II of the sleeve until the outer layer of the cable sample is pressed against the inclined surface inside the sleeve. Finally, lock the T-shaped frustum. 1.4) Repeat step 1.3) and clamp the other end of the specimen through another dynamic and static tensile test fixture suitable for cables.