Strain Regulation Device for Hopkinson Tensile Test and Its Usage Method

Abstract

The present invention discloses a strain regulation device for Hopkinson tensile testing and its usage method, belonging to the technical field of material tensile testing equipment. The device includes a specimen to be tested, Hopkinson transmission bars at both ends thereof, and Hopkinson incident bars. The specimen to be tested is connected to the Hopkinson transmission bar through fastener one, and the specimen to be tested is connected to the Hopkinson incident bar through fastener two. The specimen to be tested, fastener one, and fastener two are all arranged inside a protective sleeve; a stop component capable of cooperating with a stop groove on the inner wall of the protective sleeve is provided on fastener two. Different strain adjustments are achieved by changing the distance between fastener one and fastener two at both ends of the specimen to be tested; during the high-speed loading process, the stop component on fastener two enters the stop groove on the inner wall of the protective sleeve to prevent the Hopkinson incident bar from rebounding. The present invention simultaneously has the capabilities of strain regulation and reverse stopping, improving the reliability and accuracy during the high-speed tensile testing process of the Hopkinson pull bar.

Description

Technical Field

[0001] The present invention belongs to the technical field of material tensile test equipment, and particularly relates to a strain regulation device for Hopkinson tensile test and a using method thereof. Background Art

[0002] The research on the dynamic mechanical behavior of materials is of great significance in many fields such as aerospace equipment, military engineering design and safety protection. Due to the extreme high pressure and high strain rate conditions caused by high-speed impact, the mechanism of dominant plastic relaxation of typical microstructures inside metal materials is different from that under static load. Macroscopically, it is manifested as significant changes in the plastic deformation, adiabatic shear fracture of materials and the related physical and mechanical properties compared with the normal state, which brings challenges to obtaining dynamic parameters such as the equation of state and impact strength of materials under shock wave loading. At present, research scholars generally use Hopkinson bar devices to obtain the dynamic mechanical properties of materials under different loading strain rates. In order to reveal the mechanical response characteristics and deformation mechanism of materials under high strain rate loading of specimens, it is necessary to obtain the macroscopic morphology and microscopic structure of specimens at different strain stages under high-speed tensile conditions. Therefore, it is of great significance to realize the precise regulation of specimen strain during the high-speed tensile process of Hopkinson bar devices for the research on the dynamic mechanical behavior of materials.

[0003] Under high-speed loading conditions, the specimen and the incident bar have great momentum and inertia, and there are great technical challenges to achieve their sudden stop at the preset target strain position. At present, the existing one-way limiting devices are only applicable to the strain regulation of the tensile process with a loading strain rate less than 2000s -1 . Under impact loading at higher strain rates, after the Hopkinson incident bar collides with the limiting device, it will rebound, causing the movement to reverse and compress the specimen, thereby damaging the specimen. This will seriously affect the safety of test operation and the accuracy of test results. Therefore, considering the dynamic mechanical response characteristics of specimens and incident bars under high-speed loading conditions, it is extremely necessary and urgent to design a device with strain regulation and reverse stopping (locking) applicable to Hopkinson dynamic tensile tests. Summary of the Invention

[0004] The purpose of the present invention is to provide a strain regulation device for Hopkinson tensile test and a using method thereof, aiming to solve the technical problem that after the Hopkinson incident bar collides with the limiting device during the tensile process strain rate impact loading higher than 2000s -1 in the existing Hopkinson tensile device, it will rebound and cause damage to the specimen.

[0005] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] A strain control device for Hopkinson tensile testing comprises a sample to be tested and a first fastener and a second fastener at both ends thereof, wherein the first fastener is connected to a Hopkinson transmission rod, and the second fastener is connected to a Hopkinson incident rod. The sample to be tested, the first fastener and the second fastener are all arranged in a protective sleeve, and the Hopkinson transmission rod and the Hopkinson incident rod respectively penetrate the two ends of the protective sleeve and are connected to a tensile testing device, so as to realize the control of different strain amounts; and the second fastener is provided with a stop assembly capable of cooperating with a stop groove on the inner wall of the protective sleeve.

[0007] Preferably, the exterior and the inner cavity of the protective sleeve are both cylindrical, and the protective sleeve is a split structure; the protective sleeve includes an upper semi-cylinder and a lower semi-cylinder, and the horizontal mating surfaces of the upper semi-cylinder and the lower semi-cylinder are connected and fixed by positioning pins.

[0008] Preferably, the fastener 1 is a polygonal column, the fastener 1 is threadedly connected to the Hopkinson transmission rod, and the bottom of the fastener 1 is surrounded by a limiting boss that cooperates with the positioning groove at the left end of the inner cavity of the protective sleeve.

[0009] Preferably, the right end of the fastener 1 is a hexagonal prism, a cylindrical base is provided between the hexagonal prism and the limiting boss, and the limiting boss is a truncated cone with a larger left side and a smaller right side.

[0010] Preferably, the stopping assembly is arranged at the right end of fastener two, and the stopping assembly includes a plurality of stopping claws and an energy storage element. The stopping claw is connected to fastener two through the energy storage element, and the plurality of stopping claws are arranged at intervals at the right end of fastener two; the right end of the inner cavity of the protective sleeve is provided with a stopping groove matching the stopping claw.

[0011] Preferably, a plurality of stop claws and energy storage elements are radially evenly distributed at the two right ends of the fastener, and the stop claws can be stuck in the stop grooves.

[0012] Preferably, the energy storage element is a force storage spring, and there are four locking claws and four force storage springs. Four mounting grooves are provided on the right end face of the fastener 2. The force storage spring is rectangularly arranged in the mounting groove. One end of the force storage spring is connected to the mounting groove, and the other end is connected to the locking claw. The outer side surface of the locking claw is an inclined surface, and a protruding tongue is provided at the end of the inclined surface, and the protruding tongue can cooperate with the locking groove on the inner wall of the protective sleeve.

[0013] Preferably, the mounting groove is a rectangular notch arranged around the right end surface of the second fastener, guide blocks are symmetrically arranged on both sides of the mounting groove, and guide grooves cooperating with the guide blocks are correspondingly arranged on both sides of the stop claw.

[0014] Preferably, the second fastener has a stepped structure. From left to right, the second fastener includes a cylindrical section, a hexagonal prism section, a supporting cylindrical platform, and a supporting conical platform. The installation groove is arranged at the peripheral edge of the right end face of the supporting conical platform. The second fastener is threadedly connected to the Hopkinson incident bar.

[0015] The present invention also provides a method for using a strain regulation device for Hopkinson tensile testing, which is characterized by including the following steps:

[0016] (1) Assemble the strain regulation device for Hopkinson tensile testing as described in the claims: Both ends of the specimen to be tested are respectively connected to the Hopkinson transmission bar and the Hopkinson incident bar through the first fastener and the second fastener. Control the axial tensile strain so that the energy storage spring is in a compressed state, the stop claw is closely attached to the inner wall of the protective sleeve, and it is installed in the protective sleeve;

[0017] (2) Fix the protective sleeve on the experimental bench to prepare for the experiment;

[0018] (3) Tensile operation: Apply a tensile force to the Hopkinson incident bar. When the end face of the second fastener fits against the inner wall of the protective sleeve, the energy storage spring bounces the stop claw open, and the stop claw catches into the stop groove in the sleeve;

[0019] (4) After the tensile test is completed, disassemble the device and take samples.

[0020] The beneficial effects of adopting the above technical solutions are as follows: Compared with the prior art, in the present invention, both ends of the specimen to be tested are respectively connected to the Hopkinson transmission bar and the Hopkinson incident bar through the first fastener and the second fastener, and different strain adjustments are achieved by changing the distance between the first fastener and the second fastener; during the high-speed loading process, the stop assembly on the second fastener can enter the stop groove on the inner wall of the protective sleeve, thereby preventing the Hopkinson incident bar from rebounding. The present invention has both strain regulation and reverse stop capabilities, improving the reliability and accuracy during the high-speed tensile test of the Hopkinson bar. Description of the Drawings

[0021] The following further elaborates on the present invention in detail in conjunction with the drawings and specific embodiments.

[0022] Figure 1 It is a schematic structural diagram of a strain regulation device for Hopkinson tensile testing provided by an embodiment of the present invention;

[0023] Figure 2 It is Figure 1 the external view of the strain regulation device for Hopkinson tensile testing in

[0024] Figure 3 It is Figure 1Schematic diagram of the structure of the strain regulation device for Hopkinson tension test without the protective sleeve;

[0025] Figure 4 is Figure 1 State diagram of the second fastener fitting with the inner wall of the protective sleeve after the specimen to be tested is tensioned in [the figure];

[0026] Figure 5 is Figure 4 Partial enlarged view of area A in [the figure];

[0027] Figure 6 is Figure 1 External shape diagram of the second fastener in [the figure];

[0028] Figure 7 is Figure 6 Partial enlarged view of area B in [the figure];

[0029] Figure 8 is Figure 6 State diagram of the installation of the stop claw on the second fastener in [the figure];

[0030] Figure 9 is Figure 8 Partial enlarged view of area C in [the figure];

[0031] Figure 10 Figure 8 Schematic connection diagram of the energy storage spring and the stop claw in [the figure];

[0032] Figure 11 is Figure 2 External shape diagram of the upper half cylinder in [the figure];

[0033] In the figure: 1 - Hopkinson transmission bar, 2 - first fastener, 3 - specimen, 4 - protective sleeve, 5 - energy storage spring, 6 - second fastener, 7 - stop claw, 70 - tongue; 8 - Hopkinson incident bar, 9 - stop groove, 10 - limiting boss, 12 - installation groove, 13 - guide block, 14 - guide groove; 15 - positioning pin; 21 - hexagonal prism, 22 - base; 41 - upper half cylinder, 42 - lower half cylinder; 61 - cylindrical section, 62 - hexagonal prism section, 63 - supporting cylindrical platform, 64 - supporting conical platform. Specific implementation mode

[0034] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] Please refer to Figures 1-3, a strain regulation device for Hopkinson tensile testing provided by an embodiment of the present invention includes a specimen 3 to be tested and fasteners one 2 and fasteners two 6 at both ends thereof. The fastener one 2 is connected to the Hopkinson transmission bar 1, and the fastener two 6 is connected to the Hopkinson incident bar 8. The specimen 3 to be tested, the fastener one 2, and the fastener two 6 are all arranged in a protective sleeve 4. The Hopkinson transmission bar 1 and the Hopkinson incident bar 8 respectively penetrate through both ends of the protective sleeve 4 and are connected to a tensile testing device to achieve the regulation of different strain amounts; a stop component capable of cooperating with a stop groove 9 on the inner wall of the protective sleeve 4 is provided on the fastener two 6. By changing the distance between the fastener one 2 and the fastener two 6, different strains are adjusted. When the end face of the fastener two 6 collides with the inner side surface of the protective sleeve 4 during high-speed loading, the tensile deformation of the specimen 3 stops. At the same time, the stop component located on the fastener two 6 can enter the stop groove 9 of the protective sleeve 4 to prevent the Hopkinson incident bar 8 from rebounding. This solution has both strain regulation and reverse stop capabilities, improving the reliability and accuracy during the Hopkinson bar high-speed tensile test.

[0036] As a preferred structure, as Figure 2 , 11 shown, both the exterior and the inner cavity of the protective sleeve 4 are cylindrical, and the protective sleeve 4 is a split structure; the protective sleeve 4 includes an upper half cylinder 41 and a lower half cylinder 42, and the horizontal mating surface of the upper half cylinder 41 and the lower half cylinder 42 is fixedly connected by a positioning pin 15. The positioning pin can accurately position the upper half cylinder and the lower half cylinder, and play a limiting role for the protective sleeve axially.

[0037] During specific design, as Figure 3 shown, the fastener one 2 is a multi-prism body, the fastener one 2 is threadedly connected to the Hopkinson transmission bar 1, and a limiting boss 10 that cooperates with a positioning groove at the left end of the inner cavity of the protective sleeve 4 is provided around the bottom of the fastener one 2. In a specific embodiment, as Figure 3 shown, the right end of the fastener one 2 is a hexagonal prism 21, a cylindrical base 22 is provided between the hexagonal prism 21 and the limiting boss 10, and the limiting boss 10 is a conical table with a larger left side and a smaller right side. Using a hexagonal prism is convenient for cooperating with a conventional wrench and facilitating the connection of the fastener one and the Hopkinson transmission bar together.

[0038] In a specific embodiment of the present invention, as Figures 1-5As shown in , 8-10, the stop assembly is arranged at the right end of the fastener 2 6, and the stop assembly includes a plurality of stop claws 7 and an energy storage element. The stop claw 7 is connected to the fastener 2 6 through the energy storage element, and the plurality of stop claws 7 are arranged at intervals at the right end of the fastener 2 6; the right end of the inner cavity of the protective sleeve 4 is provided with a stop groove 9 matched with the stop claw 7. Among them, the plurality of stop claws 7 and the energy storage element are radially uniformly distributed at the right end of the fastener 2 6, and the stop claw 7 can be stuck in the stop groove 9. Specifically, the energy storage element is a force storage spring 5, and there are four stop claws 7 and force storage springs 5. Four mounting grooves 12 are arranged on the right end surface of the fastener 2 6. The force storage spring 5 is rectangularly arranged in the mounting groove 12. One end of the force storage spring 5 is connected to the mounting groove 12, and the other end is connected to the stop claw 7. The outer side surface of the stop claw 7 is an inclined surface, and a tongue 70 is arranged at the end of the inclined surface. The tongue 70 can cooperate with the stop groove 9 on the inner wall of the protective sleeve 4. When the Hopkinson incident rod is subjected to a pulling force so that the two end surfaces of the fastener are close to the inner wall of the protective sleeve, the force storage spring ejects the stop claw in an instant, and the stop claw is stuck in the stop groove in the protective sleeve, thereby avoiding rebound and improving the safety factor of the test.

[0039] As a preferred solution, Figure 6 , 7 As shown, the installation groove 12 is a rectangular notch arranged around the right end surface of the fastener 2 6, and guide blocks 13 are symmetrically arranged on both sides of the installation groove 12, and guide grooves 14 cooperating with the guide blocks 13 are correspondingly arranged on both sides of the stop claw 7. The use of the guide block can guide the stop claw, thus preventing the stop claw from detaching from the installation groove during the test.

[0040] When making specific Figure 1 , 3 As shown, the fastener 2 6 is a stepped structure, and the fastener 2 6 is composed of a cylindrical section 61, a hexagonal prism section 62, a supporting cylindrical cone 63 and a supporting truncated cone 64 from left to right. The mounting groove 12 is arranged on the edges around the right end surface of the supporting truncated cone 64, and the fastener 2 6 is threadedly connected to the Hopkinson incident rod 8.

[0041] In a specific embodiment of the present invention, the specific dimensions of each component are as follows: the test sample 3 adopts a cylindrical tensile test specimen with a total length of 30 mm, a gauge length of 6 mm, and two clamping end threads of M10*12; the diameters of the Hopkinson transmission rod 1 and the Hopkinson incident rod 8 are 14 mm, and the two rods are respectively processed with external threads M14*20 and internal threads M10*12.

[0042] The total thickness of the first fastener 2 is 15 mm, and it is internally provided with an M14 internal thread that matches the Hopkinson transmission bar 1. The length of the tool clamping section is 7 mm. The limiting boss 10 on the left end face base 22 of the hexagonal prism 21 is a trapezoidal structure with an upper base of 0.8 mm, a lower base of 2 mm, and a height of 2.5 mm.

[0043] The total thickness of the second fastener 6 is 15 mm, and it is internally provided with an M14 internal thread that matches the Hopkinson incident bar 8. The length of the tool clamping section is 7 mm. The supporting conical platform 64 on the right end face of the hexagonal prism section 62 is a trapezoidal structure with an upper base of 1 mm, a lower base of 5 mm, and a height of 1.5 mm. Four mounting grooves 12 are provided on the right end face of the supporting conical platform 64: 5.4 mm in length, 4 mm in width, and 1.88 mm in depth; there are raised guide blocks 13 on both sides inside the mounting groove 12: 2.2 mm in length, 1 mm in width, 0.4 mm in height, 0.5 mm from the bottom surface, and 2.5 mm from the inner side; the stop claw 7 with a width of 3.9 mm and a thickness of 1.88 mm is used in cooperation with the mounting groove 12 of the second fastener 6; the energy storage spring 5 is 2.3 mm long.

[0044] The protective sleeve 4 has a diameter of 39 mm and a length of 52 mm, and the inner hole diameter is 29 mm and the length is 42 mm. Stop grooves 9 are provided on both sides inside the protective sleeve: the upper base is 0.8 mm, the lower base is 1.25 mm, and the height is 1 mm; through holes with a diameter of 14.5 mm are provided at both ends of the protective sleeve 4. The upper half cylinder 41 and the lower half cylinder 42 on the upper and lower sides are positioned by a positioning pin 15. The diameter of the positioning pin 15 is 2 mm, the length is 2 mm, and it is 13 mm from one end face of the protective sleeve 4.

[0045] The present invention also provides a method for using a strain regulation device for Hopkinson tensile testing, which is characterized by including the following steps:

[0046] Step 1: Connect the energy storage spring 5 to the stop claw 7 as Figure 10 shown. Then connect the other end of the energy storage spring 5 to the second fastener 6 in the same installation manner, so that the three devices become an integral whole, as Figure 8 shown.

[0047] Step 2: Connect the two ends of the specimen 3 to the Hopkinson incident bar 8 and the Hopkinson transmission bar 1 respectively through threaded cooperation.

[0048] Step 3: Connect the first fastener 2 to the Hopkinson transmission bar 1 through threaded cooperation, and connect the second fastener 6 to the Hopkinson incident bar 8 through threaded cooperation, so that the Hopkinson transmission bar 1, the first fastener 2, the specimen 3, the second fastener 6, and the Hopkinson incident bar 8 are coaxial, and the connected integral whole is as Figure 3 shown.

[0049] Step 4: Install the lower half cylinder body 42 of the protective sleeve 4, and place the whole assembled in Step 3 into the lower half cylinder body 42, making the first fastener 2 closely adhere to the inner wall of the protective sleeve, and the limiting boss 10 with a trapezoidal end face is completely clamped into the stop groove 9.

[0050] Step 5: Use a vernier caliper to measure the distance between the end face of the first fastener 2 and the end face of the second fastener 6, adjust the position of the second fastener 6, and control the axial tensile strain. The energy storage spring 5 is in a compressed state, and the stop claw 7 closely adheres to the inner wall of the protective sleeve. The positions of all parts are as Figure 1 , 3 shown.

[0051] Step 6: Install the upper half cylinder body 41 of the protective sleeve 4, and install the upper and lower parts of the protective sleeve 4 together through the positioning pin 15, as Figure 2 shown; fix the protective sleeve 4 on the test bench to prepare for the experiment.

[0052] Step 7: Apply a tensile force to the Hopkinson incident bar 8. When the end face of the second fastener 6 is in contact with the inner wall of the protective sleeve for an instant, the energy storage spring 5 will push the stop claw 7 away, and the stop claw 7 will snap into the stop groove 9 inside the protective sleeve, as Figure 4 shown.

[0053] Step 8: After the specimen 3 is stretched, disassemble the device and take samples: Remove the upper and lower protective sleeves in sequence, take the specimen 3 off the Hopkinson incident bar 8 and the Hopkinson transmission bar 1 respectively, remove the first fastener 2 and the second fastener 6 from the Hopkinson transmission bar 1 and the Hopkinson incident bar 8, and complete the cleaning work of the device.

[0054] By using the present invention, it is possible to realize the adjustable axial strain for the Hopkinson tensile test of the specimen. The deformation relationship among the first fastener 2, the specimen to be tested 3, the protective sleeve 4, and the second fastener 6 is expressed by the following formula:

[0055]

[0056] Where ε is the axial tensile strain of the specimen to be tested 3, L is the gauge length of the specimen to be tested 3, S is the internal length of the protective sleeve, s is the distance between the end face of the first fastener 2 and the outer end face of the second fastener 6, ( S-s ) is the deformation amount of the Hopkinson incident bar 8 when stretching the specimen to be tested 3. When the size of the specimen 3 is fixed, by adjusting the position of the second fastener 6 to change the s size, the axial tensile strain size of the specimen to be tested 3 is controlled.

[0057] To sum up, the present invention has the following advantages:

[0058] 1. When conducting dynamic tests on materials, the present invention can achieve tensile constant strain by adjusting the position of the second fastener.

[0059] 2. When the force applied by the power device disappears, the specimen will not rebound because the stop claw is caught in the stop groove of the protective sleeve, ensuring the accuracy of the experimental data.

[0060] 3. The present invention uses a protective sleeve to prevent the specimen fragments from damaging the surroundings, improving the safety and reliability of the experiment.

[0061] 4. In the present invention, the cooperation between the parts is mostly threaded, with a simple structure and fast clamping speed, greatly improving the test efficiency.

[0062] 5. In the present invention, the stop groove inside the protective sleeve is a through groove that runs around the inner wall of the protective sleeve, and the structures of the upper half cylinder and the lower half cylinder are the same, with a simple structure and easy processing; the upper half cylinder and the lower half cylinder are connected by a positioning pin, which is easy to connect and improves the experimental efficiency.

[0063] 6. In the present invention, the Hopkinson transmission bar, the Hopkinson incident bar and the specimen are coaxial, and the first fastener and the second fastener are in clearance-free fit with the protective sleeve. During the test, the tensile forces of the Hopkinson transmission bar and the Hopkinson incident bar on the specimen are collinear and opposite, avoiding the specimen from being offset by force and generating torsion, and ensuring the accuracy of the test results.

[0064] 7. In the present invention, all parts are replaceable parts. When a part is damaged, a single part can be replaced, saving costs.

[0065] In the above description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed above.

Claims

1. A strain regulation device for Hopkinson tensile testing, characterized in that: It includes a sample to be tested and a fastener 1 and a fastener 2 at both ends thereof, wherein the fastener 1 is connected to a Hopkinson transmission rod, and the fastener 2 is connected to a Hopkinson incident rod. The sample to be tested, the fastener 1 and the fastener 2 are all arranged in a protective sleeve, and the Hopkinson transmission rod and the Hopkinson incident rod respectively penetrate the two ends of the protective sleeve and are connected to a tensile test device, so as to realize the regulation of different strain amounts; the fastener 2 is provided with a stop assembly capable of cooperating with a stop groove on the inner wall of the protective sleeve; The exterior and the inner cavity of the protective sleeve are both cylindrical, and the protective sleeve is a split structure; the protective sleeve comprises an upper semi-cylinder and a lower semi-cylinder, and the horizontal mating surfaces of the upper semi-cylinder and the lower semi-cylinder are connected and fixed by a positioning pin; The stopping assembly is arranged at the right end of fastener two, and the stopping assembly includes multiple stopping claws and energy storage elements. The stopping claw is connected to fastener two through the energy storage element, and multiple stopping claws are arranged at intervals at the right end of fastener two; the right end of the inner cavity of the protective sleeve is provided with a stopping groove matching with the stopping claw; multiple stopping claws and energy storage elements are radially evenly distributed at the right end of fastener two, and the stopping claw can be stuck in the stopping groove.

2. The strain regulation device for Hopkinson tensile test according to claim 1, characterized in that: The fastener 1 is a polygonal column, and is threadedly connected to the Hopkinson transmission rod. The bottom of the fastener 1 is surrounded by a limiting boss that cooperates with the positioning groove at the left end of the inner cavity of the protective sleeve.

3. The strain regulation device for Hopkinson tensile test according to claim 2, characterized in that: The right end of the fastener 1 is a hexagonal prism, a cylindrical base is provided between the hexagonal prism and the limiting boss, and the limiting boss is a truncated cone with a larger left side and a smaller right side.

4. The strain regulation device for Hopkinson tensile test according to claim 1, wherein: The energy storage element is a force storage spring, and there are four locking claws and four force storage springs. Four mounting grooves are arranged on the right end face of the fastener 2. The force storage spring is rectangularly arranged in the mounting groove. One end of the force storage spring is connected to the mounting groove, and the other end is connected to the locking claw. The outer side surface of the locking claw is an inclined surface, and a protruding tongue is arranged at the end of the inclined surface, and the protruding tongue can cooperate with the locking groove on the inner wall of the protective sleeve.

5. The strain regulation device for Hopkinson tensile test according to claim 4, characterized in that: The installation groove is a rectangular notch arranged around the right end surface of the second fastener. Guide blocks are symmetrically arranged on both sides of the installation groove, and guide grooves matching with the guide blocks are correspondingly arranged on both sides of the stop claw.

6. The strain regulation device for Hopkinson tensile test according to claim 4, characterized in that: The fastener 2 is a stepped structure, and the fastener 2 is composed of a cylindrical section, a hexagonal prism section, a supporting cylindrical cone and a supporting truncated cone from left to right. The mounting groove is arranged on the edges around the right end face of the supporting truncated cone, and the fastener 2 is threadedly connected to the Hopkinson incident rod.

7. A method for using a strain regulation device for Hopkinson tensile testing, characterized in that, The following steps are involved: (1) Assembling the strain control device for Hopkinson tensile test as described in any one of claims 4 to 6: the two ends of the test sample are connected to the Hopkinson transmission rod and the Hopkinson incident rod through fastener 1 and fastener 2 respectively, and the axial tensile strain is controlled so that the force storage spring is in a compressed state, the stop claw is close to the inner wall of the protective sleeve, and is installed in the protective sleeve; (2) Fix the protective sleeve on the experimental table and prepare for the experiment; (3) Stretching operation: Apply tension to the Hopkinson incident rod. When the end face of the second fastener fits against the inner wall of the protective sleeve, the force storage spring will pop the stop claw open, and the stop claw will be stuck in the stop groove in the sleeve. After stretching is completed, disassemble the device and take samples.

Images