Separated Hopkinson pressure bar experiment system for low-temperature in-situ observation

Abstract

The invention relates to the technical field of Hopkinson pressure bar experiments, in particular to a split Hopkinson pressure bar experiment system for low-temperature in-situ observation, which comprises a low-temperature box, refrigeration equipment, an incident bar and a transmission bar, strain gauges are arranged on the incident bar and the transmission bar, and the two strain gauges are electrically connected with a dynamic strain meter. The low-temperature box comprises a shell, an internal channel arranged in the shell and a secondary refrigerant chamber formed between the inner surface of the shell and the outer surface of the internal channel. The refrigerating equipment is used for cooling a secondary refrigerant, and the secondary refrigerant circularly flows between the secondary refrigerant chamber and the secondary refrigerant box through a pump and a pipeline; the internal channel comprises a longitudinal pipeline, transverse pipelines and a vertical pipeline, the two transverse pipelines are fixedly communicated with the left side and the right side of the longitudinal pipeline, and the incident bar and the transmission bar extend into the longitudinal pipeline through the two transverse pipelines respectively. According to the invention, a secondary refrigerant can be prevented from entering a microscopic hole of the test piece, experimental errors are reduced, and working efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of Hopkinson bar experiments, and particularly to a split Hopkinson bar experimental system for low-temperature in-situ observation. Background Technique

[0002] The Hopkinson bar experiment is an important experimental method for evaluating the dynamic mechanical properties of materials. Its basic principle is as follows: Based on the one-dimensional stress wave theory, the Hopkinson bar generates a stress wave through an impact bar hitting an incident bar. This wave splits into a transmitted wave and a reflected wave in the specimen, and strain gauges record these waveform data for calculating the stress-strain relationship of the material. This technology has become the core means for studying the dynamic response of materials under extreme conditions such as high-speed impact or explosion.

[0003] Low temperature is a common environment for Hopkinson bar experiments. The operation method is to place the workpiece in a low-temperature environment and then conduct the experiment to test the dynamic mechanical properties of the specimen in the low-temperature environment.

[0004] However, the current low-temperature environmental chambers are usually enclosed. For example, the Chinese patent application with the publication number CN108776060A discloses a temperature compensation device for real-time low-temperature split Hopkinson bar tests. It includes a low-temperature environmental chamber, a low-temperature liquid nitrogen bottle, and a pneumatic pump. Insulation materials are provided in the sandwich walls of the box body and the box door of the low-temperature environmental chamber. A liquid nitrogen input pipe is provided at the top, and rod holes are respectively opened on the symmetric two side walls; an observation window is provided on the box door. The liquid nitrogen input pipe is connected to a liquid nitrogen output pipe extending into the bottom of the low-temperature liquid nitrogen bottle; the air outlet of the pneumatic pump is connected to the air inlet pipe of the low-temperature liquid nitrogen bottle through a trachea. The above technical solution cannot achieve in-situ observation of the deformation process of the specimen, and moreover, directly cooling the specimen with liquid nitrogen will cause liquid nitrogen to enter the microscopic pores of the specimen, thereby introducing errors in the experimental results and having an adverse impact on the actual test results. Summary of the Invention

[0005] The purpose of the present invention is to provide a split Hopkinson bar experimental system for low-temperature in-situ observation to solve the problems raised in the above background technique.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A split Hopkinson bar experimental system for low-temperature in-situ observation, including a low-temperature box, a refrigeration device, an incident bar, and a transmission bar. Strain gauges are provided on both the incident bar and the transmission bar, and both strain gauges are electrically connected to a dynamic strain gauge. The low-temperature box includes an outer shell, an internal channel provided inside the outer shell, and a coolant chamber formed between the inner surface of the outer shell and the outer surface of the internal channel; The refrigeration device is used to cool the coolant, and the coolant circulates between the coolant chamber and the coolant tank through a pump and a pipeline; The internal channel includes a longitudinal pipe, a transverse pipe and a vertical pipe. Among them, the longitudinal pipe runs through the housing in the front-back direction. Two transverse pipes are fixedly connected to the left and right sides of the longitudinal pipe. The incident rod and the transmission rod extend into the interior of the longitudinal pipe through the two transverse pipes respectively. The bottom end of the vertical pipe is communicated with the longitudinal pipe, and the top end of the vertical pipe is flush with the top surface of the housing; A longitudinal partition is slidably arranged longitudinally inside the longitudinal pipe. At least three specimens are arranged equidistantly along the longitudinal direction on the longitudinal partition. Moving the longitudinal partition longitudinally can make the specimens pass sequentially under the vertical pipe; A high-speed camera is arranged at the top of the vertical pipe for photographing the specimens arranged between the incident rod and the transmission rod.

[0007] Preferably, a plurality of vertical partitions are fixedly installed on the top of the longitudinal partition through installation vertical bars; The left and right sides of the longitudinal partition are respectively in contact with the left and right side surfaces of the inner wall of the longitudinal pipe; The bottom end of the vertical partition abuts against the upper surface of the longitudinal partition. The left edge, right edge and top edge of the vertical partition are respectively in contact with the left side surface, right side surface and top side surface of the inner wall of the longitudinal pipe; One specimen is arranged between every two adjacent vertical partitions. The specimens are arranged on the top of the flexible coiled felt.

[0008] Preferably, the longitudinal partition divides the longitudinal pipe into a lower chamber and an upper chamber. The vertical partitions are arranged in the upper chamber; A first baffle is fixed at one end of the lower chamber and is hermetically connected to the longitudinal pipe; A first longitudinal slide bar is fixed inside the lower chamber. The longitudinal partition can slide longitudinally along the first longitudinal slide bar; A vertically slidable bracket is arranged on the longitudinal partition. A second longitudinal slide bar for supporting the bracket is also fixed inside the lower chamber; The second longitudinal slide bar includes a horizontal slide bar. When the bottom end of the bracket contacts the horizontal slide bar, the specimen is lifted by the bracket to be separated from the flexible coiled felt. When the bracket moves under the vertical pipe, the specimen contacts the flexible coiled felt.

[0009] Preferably, the second longitudinal slide bar further includes a first inclined bar fixedly connected to one end of the horizontal slide bar.

[0010] Preferably, tempered glass is arranged at the top of the vertical pipe; Heat insulation components are arranged at both the entrance and the exit of the upper chamber; The inner diameter of the transverse pipe is slightly larger than the diameters of the incident rod and the transmission rod; The second longitudinal slide bar further includes a second inclined bar fixedly connected to the first inclined bar. The first inclined bar and the second inclined bar are arranged in a V shape, and the connection position of the first inclined bar and the second inclined bar is under the vertical pipe; At the other end of the lower chamber, a second baffle plate is fixed and is hermetically connected to the longitudinal pipe.

[0011] Preferably, the bracket includes two guide sleeves vertically penetrating the longitudinal partition, a vertical guide rod slidably penetrating the guide sleeves, a longitudinal rod fixed to the top of the vertical guide rod by fasteners, and transverse circular shafts fixed to both ends of the longitudinal rod; The two guide sleeves are respectively arranged on the left and right sides of the flexible coiled felt; The bottom end of the vertical guide rod is provided with a spherical bottom.

[0012] Preferably, a positioning frame is provided around the tempered glass, and a lighting source is fixed to the top of the tempered glass.

[0013] Preferably, the heat insulation component includes a heat insulation door panel, a sliding sleeve fixedly connected to the heat insulation door panel through a connecting plate, and a transverse shaft fixedly connected to the outer shell, and the sliding sleeve is slidably sleeved on the transverse shaft.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: Firstly, the present invention cools the internal channel by using a coolant, and then cools the test piece by using the low-temperature environment inside the internal channel, avoiding the direct contact between the test piece and the coolant, preventing the coolant from entering the microscopic pores of the test piece, and reducing experimental errors; at the same time, the cooling process of the test piece is relatively slow, thus matching the cooling process of the test piece in the external natural environment, effectively avoiding the adverse impact on the experimental results caused by the sudden cooling of the test piece; then, through the provided longitudinal partition, at least three test pieces can be cooled synchronously in the longitudinal pipe, and the cooling consistency is good. More importantly, by pushing the longitudinal partition, multiple test pieces can be sequentially moved to the test position, and the test pieces located at the test position are all in the best experimental temperature state, saving the cooling time before the experiment for each test piece and significantly improving the experimental efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall system structure of the present invention; Figure 2 It is a schematic diagram of the refrigeration equipment of the present invention; Figure 3 It is a schematic diagram of the structures of the low-temperature box, the incident rod and the transmission rod of the present invention; Figure 4 It is a schematic diagram of the sectional three-dimensional structure of the outer shell of the present invention; Figure 5 It is a schematic diagram of the structure of the internal channel of the present invention; Figure 6 It is a schematic diagram of the sectional three-dimensional structure of the internal channel of the present invention; Figure 7 It is a schematic diagram of the side sectional structure of the low-temperature box of the present invention; Figure 8 This is a schematic structural diagram of the specimen of the present invention inside the internal channel; Figure 9 This is a schematic structural diagram of the second longitudinal slide of the present invention; Figure 10 This is a schematic side view structural diagram of the longitudinal partition of the present invention; Figure 11 This is a schematic structural diagram of the bracket of the present invention; Figure 12 This is a schematic side view sectional structural diagram of the longitudinal partition and the guide sleeve of the present invention.

[0016] In the figure: 100, low-temperature box; 1, outer shell; 11, discharge port; 12, inlet; 2, internal channel; 21, longitudinal pipe; 211, lower chamber; 212, upper chamber; 2121, inlet; 2122, outlet; 213, first longitudinal slide; 214, second longitudinal slide; 2141, horizontal slide; 2142, first inclined bar; 2143, second inclined bar; 215, first baffle; 216, second baffle; 22, transverse pipe; 23, vertical pipe; 24, longitudinal partition; 25, vertical partition; 26, installation vertical bar; 27, flexible coiled felt; 28, bracket; 281, vertical guide rod; 282, guide sleeve; 283, longitudinal rod; 284, transverse round shaft; 285, fastener; 286, spherical bottom; 3, coolant chamber; 4, toughened glass; 41, positioning frame; 42, lighting source; 5, heat insulation component; 51, heat insulation door panel; 52, connecting plate; 53, transverse shaft; 54, sliding sleeve; 200, incident rod; 300, transmission rod; 400, strain gauge; 500, dynamic strain gauge; 600, high-speed camera; 700, refrigeration equipment; 701, compressor; 702, condenser; 703, expansion valve; 704, evaporator; 800, pump; 900, pipeline; 1000, coolant tank; 1100, specimen. Detailed implementation manners

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0018] Please refer to Figures 1-12 , the present invention provides a technical solution: A split Hopkinson pressure bar experimental system for low-temperature in-situ observation, including a low-temperature chamber 100, a refrigeration device 700, an incident bar 200, and a transmission bar 300. Strain gauges 400 are provided on both the incident bar 200 and the transmission bar 300, and both strain gauges 400 are electrically connected to a dynamic strain gauge 500. The working principle of the above structure is prior art and will not be elaborated here.

[0019] Different from the prior art, the low-temperature chamber 100 in the technical solution of the present invention includes a housing 1, an internal channel 2 provided inside the housing 1, and a coolant chamber 3 formed between the inner surface of the housing 1 and the outer surface of the internal channel 2; among them, the housing 1 has a heat preservation effect. For example, in some embodiments, the housing 1 includes an internal metal layer and an external heat preservation layer to achieve the heat preservation effect. In other embodiments, other heat preservation structures can also be used to achieve the heat preservation effect of the housing 1; the internal channel 2 can be made of stainless steel as a whole, and its function is to quickly transfer the temperature in the coolant in the coolant chamber 3 to the inside of the internal channel 2 to cool the specimen 1100 inside the internal channel 2.

[0020] The refrigeration device 700 is used to cool the coolant. The coolant circulates between the coolant chamber 3 and the coolant tank 1000 through a pump 800 and a pipeline 900. Further, the housing 1 is communicated with the pipeline 900 through an outlet 11 and an inlet 12; specifically, the refrigeration device 700 includes a compressor 701, a condenser 702, an expansion valve 703, and an evaporator 704. Among them, the coolant is cooled by using the evaporation and heat absorption of the evaporator 704. The refrigeration principle of the refrigeration device 700 is prior art and will not be elaborated here.

[0021] The internal channel 2 includes a longitudinal pipeline 21, a transverse pipeline 22, and a vertical pipeline 23. Here, for the convenience of understanding and description, the longitudinal direction of the longitudinal pipeline 21 can be defined as the front-back direction of the housing 1, and the transverse direction of the transverse pipeline 22 can be defined as the left-right direction of the housing 1. Among them, the longitudinal pipeline 21 runs through the housing 1 in the front-back direction, and the front and rear end faces of the longitudinal pipeline 21 are respectively flush with the front and rear end faces of the housing 1. Two transverse pipelines 22 are fixedly connected to the left and right sides of the longitudinal pipeline 21. The incident bar 200 and the transmission bar 300 respectively extend into the interior of the longitudinal pipeline 21 through the two transverse pipelines 22. The two end faces of the two transverse pipelines 22 that are separated are respectively flush with the left and right side faces of the housing 1. The bottom end of the vertical pipeline 23 is communicated with the longitudinal pipeline 21, and the top end of the vertical pipeline 23 is flush with the top surface of the housing 1; during actual operation, the specimen 1100 passes through the longitudinal pipeline 21 in the front-to-back direction.

[0022] Due to the errors in the Hopkinson bar experiment, it is necessary to conduct three experiments on at least three specimens 1100 to reduce the experimental errors and improve the accuracy of the experimental results. Therefore, in this technical solution, a longitudinal partition 24 is slidably arranged longitudinally inside the longitudinal pipe 21, and at least three specimens 1100 are arranged equidistantly along the longitudinal direction on the longitudinal partition 24. Moving the longitudinal partition 24 longitudinally can enable the specimens 1100 to pass sequentially under the vertical pipe 23. For the convenience of description, this technical solution takes three specimens 1100 as an example for illustration. Specifically, as shown in the figure, the three specimens 1100 are placed equidistantly on the longitudinal partition 24, and the longitudinal partition 24 is pushed to the position as shown in Figure 10 Figure. At this time, the specimen 1100 at the rearmost position is located at the test position, and this specimen 1100 is clamped and positioned by the two incident bars 200 and the transmission bar 300. When the temperature of this specimen 1100 drops to the predetermined temperature, the test can be carried out. The other two specimens 1100 are in the waiting test workstations. After the specimen 1100 at the rearmost position completes the test, the specimen 1100 in the middle of the three specimens 1100 can be pushed to the test position by pushing the longitudinal partition 24 backward to conduct the second test. Since the three specimens 1100 are all located inside the longitudinal pipe 21 for synchronous cooling, when testing the specimen 1100 in the middle, the test can be quickly started without waiting for this specimen 1100 to cool down. Similarly, the specimen 1100 at the foremost position can also be quickly tested without waiting for cooling, thus improving the overall work efficiency.

[0023] The high-speed camera 600 is arranged at the top of the vertical pipe 23 and is used to photograph the specimen 1100 arranged between the incident bar 200 and the transmission bar 300.

[0024] In this technical solution, the reason for arranging the longitudinal pipe 21 in the front-back direction is as follows: Since the entire outer shell 1 is in a horizontal state, and all the test pieces 1100 are cylindrical, and the test pieces 1100 need to be coaxial with the incident bar 200 and the transmission bar 300, the longitudinally arranged longitudinal pipes 21 in the front-back direction can facilitate the sequential movement of multiple test pieces 1100 between the incident bar 200 and the transmission bar 300; the reason for arranging the vertical pipe 23 vertically is as follows: Since all the test pieces 1100 during the experiment need to be placed on the flexible coiled felt 27 (or other flexible support pads), and the vertical pipe 23 serves as the channel for the high-speed camera 600 to photograph the test pieces 1100. If it is designed in the front-back direction, then at this time, the high-speed camera 600 can only photograph the cracking or explosion process of the test pieces 1100 from the front or the back. Thus, the cracking or explosion process of the test pieces 1100 photographed at this time will be affected by the flexible coiled felt 27, which is not conducive to improving the accuracy of in-situ observation. However, since the vertical pipe 23 in this technical solution is arranged vertically, the high-speed camera 600 directly photographs the test pieces 1100 from top to bottom. At this time, there are no obstacles similar to the flexible coiled felt 27 on both sides of the front and back of the top position of the test pieces 1100 facing the high-speed camera 600. Therefore, the cracking or explosion process of the test pieces 1100 will not be affected by external objects, and the cracking or explosion process of the test pieces 1100 photographed by the high-speed camera 600 is the most real picture, improving the accuracy of in-situ observation.

[0025] In the above technical solution, first, the internal channel 2 is cooled by using a coolant, and then the test pieces 1100 are cooled by using the low-temperature environment inside the internal channel 2, avoiding the direct contact between the test pieces 1100 and the coolant, preventing the coolant from entering the microscopic pores of the test pieces, and reducing experimental errors; at the same time, the cooling process of the test pieces 1100 is relatively slow, so it is in line with the cooling process of the test pieces 1100 in the external natural environment, effectively avoiding the adverse impact on the experimental results caused by the sudden cooling of the test pieces 1100; then, through the arranged longitudinal partition 24, at least three test pieces 1100 can be cooled synchronously in the longitudinal pipe 21, and the cooling consistency is good. More importantly, by pushing the longitudinal partition 24, multiple test pieces 1100 can be sequentially moved to the test position, and the test pieces 1100 located at the test position are all in the best experimental temperature state, saving the cooling time of each test piece 1100 before the experiment and significantly improving the experimental efficiency.

[0026] At the top of the longitudinal partition 24, a number of vertical partitions 25 are fixedly installed through the installation vertical bars 26. In this embodiment, the installation vertical bars 26 can be made of stainless steel, and the vertical partitions 25 can be made of plastic or rubber materials; the left and right sides of the longitudinal partition 24 are respectively in contact with the left and right side surfaces of the inner wall of the longitudinal pipe 21; the bottom end of the vertical partition 25 abuts against the upper surface of the longitudinal partition 24, and the left edge, right edge and top edge of the vertical partition 25 are respectively in contact with the left side surface, right side surface and top side surface of the inner wall of the longitudinal pipe 21; a test piece 1100 is arranged between every two adjacent vertical partitions 25, and the test piece 1100 is arranged on the top of the flexible felt 27; the purpose of the above settings is: to make the adjacent two vertical partitions 25 cooperate with the longitudinal partition 24 and the inner wall surface of the longitudinal pipe 21 to achieve sealing in the front, back, left and right and downward directions, and only the top is left to cooperate with the vertical pipe 23 for the convenience of the high-speed camera 600 to take pictures, so that the residue after each test piece 1100 test can be stored separately, and the residues of the test pieces 1100 are prevented from being mixed together.

[0027] The longitudinal partition 24 divides the longitudinal pipe 21 into two parts, a lower chamber 211 and an upper chamber 212. The vertical partitions 25 are arranged in the upper chamber 212; one end of the lower chamber 211 is fixed with a first baffle 215 that is hermetically connected to the longitudinal pipe 21. The first baffle 215 is used to prevent heat exchange between the external environment and the inside of the lower chamber 211 through one end of the lower chamber 211; a first longitudinal slide bar 213 is fixed inside the lower chamber 211, and the longitudinal partition 24 can slide longitudinally along the first longitudinal slide bar 213. The first longitudinal slide bar 213 is used to support the longitudinal partition 24; a vertically slidable bracket 28 is arranged on the longitudinal partition 24, and a second longitudinal slide bar 214 for supporting the bracket 28 is also fixed inside the lower chamber 211. The second longitudinal slide bar 214 is used to limit the height position of the bracket 28; specifically, the second longitudinal slide bar 214 includes a horizontal slide bar 2141; when the bottom end of the bracket 28 contacts the horizontal slide bar 2141, the test piece 1100 is lifted by the bracket 28 to be separated from the flexible felt 27. When the bracket 28 moves to directly below the vertical pipe 23, the test piece 1100 contacts the flexible felt 27.

[0028] As Figure 10 shown, when the bottom end of the bracket 28 contacts the horizontal slide bar 2141, the bracket 28 at this time lifts the test piece 1100, making the test piece 1100 separated from the flexible felt 27. The bracket 28 at this time plays a role in limiting the position of the test piece 1100 thereon, preventing the test piece 1100 from having a position deviation due to factors such as vibration or inertia, and is used to improve the coaxiality between the test piece 1100, the incident rod 200 and the transmission rod 300.

[0029] Specifically, as Figure 11 and Figure 12As shown in the figure, the bracket 28 includes two guide sleeves 282 vertically penetrating the longitudinal partition 24, a vertical guide rod 281 slidably penetrating the guide sleeves 282, a longitudinal rod 283 fixed to the top of the vertical guide rod 281 by fasteners 285, and transverse circular shafts 284 fixed to both ends of the longitudinal rod 283. Each specimen 1100 is supported and limited by four transverse circular shafts 284. Under the action of its own gravity, the specimen 1100 will roll to a state of contacting the four transverse circular shafts 284, so that the position of the specimen 1100 in the front-back direction is limited by the four transverse circular shafts 284. Further, the longitudinal rods 283 on the left and right sides of the specimen 1100 can limit the specimen 1100 in the left-right direction; the two guide sleeves 282 are respectively arranged on the left and right sides of the flexible felt 27; a spherical bottom 286 is arranged at the bottom end of the vertical guide rod 281, and the spherical bottom 286 can reduce the friction between the vertical guide rod 281 and the horizontal slide bar 2141.

[0030] Further, the second longitudinal slide bar 214 further includes a first inclined bar 2142 fixedly connected to one end of the horizontal slide bar 2141. The first inclined bar 2142 is used to make the first inclined bar 2142 slowly descend, ensuring that the specimen 1100 can stably fall on the corresponding flexible felt 27 and preventing the specimen 1100 from shifting.

[0031] The basic principle of the above technical solution is as follows: When the spherical bottom 286 of the bracket 28 contacts the horizontal slide bar 2141, the horizontal slide bar 2141 will support the bracket 28 at the highest position. At this time, the specimen 1100 on the bracket 28 will also be separated from the flexible felt 27 due to the support of the bracket 28. The four transverse circular shafts 284 of the bracket 28 are used to limit the front-back position of the specimen 1100, and the two longitudinal rods 283 of the bracket 28 can limit the specimen 1100 in the left-right direction; when the longitudinal partition 24 is pushed backward, the bracket 28 will move backward together with the longitudinal partition 24. When the spherical bottom 286 at the bottom of the bracket 28 moves to the rearmost end of the horizontal slide bar 2141, as the longitudinal partition 24 continues to move backward, the spherical bottom 286 will directly transition to the first inclined bar 2142. After that, as the first inclined bar 2142 gradually descends, the height of the bracket 28 will also gradually decrease, finally making the specimen 1100 gradually move to the test position and making the specimen 1100 contact the flexible felt 27. When the longitudinal partition 24 stops moving, the specimen 1100 just stays at the test position. And due to the limiting effect of the bracket 28 and the specimen 1100, the specimen 1100 is exactly coaxial with the incident rod 200 and the transmission rod 300 when it is at the test position, and the test can be carried out without fine adjustment of the position of the specimen 1100, further improving the overall experimental efficiency; moreover, since the internal channel 2 is closed, not needing to adjust the position of the specimen 1100 also brings convenience to the whole experimental process.

[0032] At the top of the vertical pipe 23, there is a tempered glass 4. On the one hand, the tempered glass 4 is used to prevent the debris from the explosion of the specimen 1100 from scratching the lens of the high-speed camera 600. On the other hand, it is also used to prevent the vertical pipe 23 from exchanging heat with the external environment through the opening at its top, and has good heat preservation effect. A positioning frame 41 is provided around the tempered glass 4, and the positioning frame 41 is used to limit the position of the tempered glass 4. And a lighting source 42 is fixed on the top of the tempered glass 4, and the lighting source 42 is used to enable the high-speed camera 600 to capture a clearer picture; Heat preservation components 5 are provided at both the inlet 2121 and the outlet 2122 of the upper chamber 212. The heat preservation component 5 includes a heat preservation door panel 51, a sliding sleeve 54 fixedly connected to the heat preservation door panel 51 through a connecting plate 52, and a transverse shaft 53 fixedly connected to the housing 1. The transverse shaft 53 can adopt a spline shaft, and the sliding sleeve 54 can be a spline sleeve, so as to prevent the sliding sleeve 54 from rotating on the transverse shaft 53, ensuring that the heat preservation door panel 51 can block the inlet 2121 and the outlet 2122. The sliding sleeve 54 is slidably sleeved on the transverse shaft 53. The heat preservation door panel 51 can be translated along the axial direction of the transverse shaft 53, so as to open or close the inlet 2121 and the outlet 2122 of the upper chamber 212.

[0033] The inner diameter of the transverse pipe 22 is slightly larger than the diameters of the incident rod 200 and the transmission rod 300. For example, the difference between the inner diameter of the transverse pipe 22 and the diameters of the incident rod 200 and the transmission rod 300 is within 1 mm, which has a heat preservation effect.

[0034] The second longitudinal slide 214 further includes a second inclined strip 2143 fixedly connected to the first inclined strip 2142. The first inclined strip 2142 and the second inclined strip 2143 are arranged in a V shape, and the connection position of the first inclined strip 2142 and the second inclined strip 2143 is directly below the vertical pipe 23; At the other end of the lower chamber 211, a second baffle 216 fixedly connected to the longitudinal pipe 21 is fixed; The setting of the second inclined strip 2143 is used to enable the bracket 28 to rise along the second inclined strip 2143 to the highest position, ensuring that the bracket 28 can smoothly pass through the outlet 2122. In this way, the second baffle 216 can be fixed at the other end of the lower chamber 211 to prevent the external environment from exchanging heat with the inside of the lower chamber 211 through the other end of the lower chamber 211; That is, the second inclined strip 2143 cooperates with the second baffle 216, the first baffle 215, and the longitudinal partition 24 to achieve the full enclosure of the lower chamber 211.

[0035] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A split Hopkinson pressure bar experimental system for low-temperature in-situ observation, comprising a low-temperature chamber, a refrigeration device, an incident bar, and a transmission bar. Strain gauges are provided on both the incident bar and the transmission bar, and both strain gauges are electrically connected to a dynamic strain gauge. It is characterized in that: The low-temperature chamber includes a housing, an internal channel provided inside the housing, and a coolant chamber formed between the inner surface of the housing and the outer surface of the internal channel; The refrigeration device is used to cool the coolant, and the coolant circulates between the coolant chamber and the coolant tank through a pump and pipes; The internal channel includes a longitudinal pipe, a transverse pipe, and a vertical pipe. Among them, the longitudinal pipe penetrates the housing in the front-rear direction, and two transverse pipes are fixedly connected to the left and right sides of the longitudinal pipe. The incident bar and the transmission bar extend into the interior of the longitudinal pipe through the two transverse pipes respectively. The bottom end of the vertical pipe is communicated with the longitudinal pipe, and the top end of the vertical pipe is flush with the top surface of the housing; A longitudinal partition is slidably arranged longitudinally inside the longitudinal pipe, and at least three specimens are arranged equidistantly along the longitudinal direction on the longitudinal partition. By moving the longitudinal partition longitudinally, the specimens can pass sequentially under the vertical pipe; A high-speed camera is arranged at the top of the vertical pipe for photographing the specimens arranged between the incident bar and the transmission bar.

2. The split Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 1, wherein, A plurality of vertical partitions are fixedly installed at the top of the longitudinal partition through installation vertical bars; The left and right sides of the longitudinal partition are respectively in contact with the left and right side surfaces of the inner wall of the longitudinal pipe; The bottom end of the vertical partition abuts against the upper surface of the longitudinal partition, and the left edge, right edge, and top edge of the vertical partition are respectively in contact with the left side surface, right side surface, and top side surface of the inner wall of the longitudinal pipe; One specimen is arranged between every two adjacent vertical partitions, and the specimen is arranged on the top of a flexible felt; 3. The split Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 2, wherein, The longitudinal partition divides the longitudinal pipe into two parts, a lower chamber and an upper chamber, and the vertical partition is arranged in the upper chamber; A first baffle plate fixedly connected to the longitudinal pipe in a sealed manner is fixed at one end of the lower chamber; A first longitudinal slide bar is fixed inside the lower chamber, and the longitudinal partition can slide longitudinally along the first longitudinal slide bar; A vertically slidable bracket is arranged on the longitudinal partition, and a second longitudinal slide bar for supporting the bracket is also fixed inside the lower chamber; The second longitudinal slide bar includes a horizontal slide bar; when the bottom end of the bracket contacts the horizontal slide bar, the specimen is lifted by the bracket to be separated from the flexible felt, and when the bracket moves under the vertical pipe, the specimen contacts the flexible felt.

4. A split Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 3, characterized in that, The second longitudinal slide bar further includes a first inclined bar fixedly connected to one end of the horizontal slide bar.

5. The split Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 4, wherein Tempered glass is arranged at the top of the vertical pipe; Heat preservation components are arranged at both the inlet and outlet of the upper chamber; The inner diameter of the transverse pipe is slightly larger than the diameters of the incident bar and the transmission bar; The second longitudinal slide bar further includes a second inclined bar fixedly connected to the first inclined bar. The first inclined bar and the second inclined bar are arranged in a V shape, and the connection position of the first inclined bar and the second inclined bar is located directly below the vertical pipe; A second baffle plate fixedly connected to the longitudinal pipe in a sealed manner is fixed at the other end of the lower chamber; 6. The split Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 5, characterized in that, The bracket includes two guide sleeves vertically penetrating the longitudinal partition, a vertical guide rod slidably penetrating the guide sleeves, a longitudinal rod fixed to the top of the vertical guide rod through a fastener, and transverse round shafts fixed to both ends of the longitudinal rod; The two guide sleeves are respectively arranged on the left and right sides of the flexible felt; The bottom end of the vertical guide rod is provided with a spherical bottom.

7. A split Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 5, characterized in that, A positioning frame is provided around the tempered glass, and a lighting source is fixed to the top of the tempered glass.

8. The split Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 5, characterized in that The heat preservation component includes a heat preservation door panel, a sliding sleeve fixedly connected to the heat preservation door panel through a connecting plate, and a transverse shaft fixedly connected to the outer shell. The sliding sleeve is slidably sleeved on the transverse shaft.

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