A split-Hopkinson pressure bar experimental system for low-temperature in-situ observation

Abstract

The present invention relates to the technical field of Hopkinson pressure bar experiments, and in particular to a separate Hopkinson pressure bar experimental system for low-temperature in-situ observation. The system comprises a cryogenic chamber, a refrigeration device, an incident rod, and a transmission rod. Both the incident rod and the transmission rod are provided with strain gauges, both of which are electrically connected to a dynamic strain gauge. The cryogenic chamber comprises an outer shell, an internal channel disposed within 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 a coolant, which circulates between the coolant chamber and the coolant chamber via a pump and a pipeline. The internal channel comprises a longitudinal pipeline, a transverse pipeline, and a vertical pipeline. The two transverse pipelines are fixedly connected to the left and right sides of the longitudinal pipeline. The incident rod and the transmission rod extend into the interior of the longitudinal pipeline respectively through the two transverse pipelines. The present invention can prevent the coolant from entering microscopic pores of a specimen, reduce experimental errors, and improve work efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of Hopkinson pressure bar experiments, in particular to a separate Hopkinson pressure bar experiment system for low-temperature in-situ observation. Background Art

[0002] The Hopkinson bar test is an important experimental method for evaluating the dynamic mechanical properties of materials. Its basic principle is: Based on one-dimensional stress wave theory, a striking bar impacts an incident bar, generating a stress wave. This wave splits into a transmitted wave and a reflected wave in the specimen. Strain gauges record these waveforms and use them to calculate the material's stress-strain relationship. This technique has become a core tool 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 the Hopkinson pressure bar test. The operation method is to place the workpiece in a low temperature environment and then conduct the test, so as to test the dynamic mechanical properties of the specimen in a low temperature environment.

[0004] However, current low-temperature environmental chambers are usually closed. For example, the Chinese invention patent application with publication number CN108776060A discloses a temperature compensation device for a real-time low-temperature split-Hopkinson pressure bar test. It includes a low-temperature environmental chamber, a low-temperature liquid nitrogen bottle, and an air pressure pump. The inner walls of the box body and the door of the low-temperature environmental chamber are both provided with insulation material, a liquid nitrogen input pipe is provided at the top, and rod holes are respectively provided on the symmetrical two side walls; an observation window is provided on the door. The liquid nitrogen input pipe is connected to the liquid nitrogen output pipe extending into the bottom of the low-temperature liquid nitrogen bottle; the air outlet of the air pressure pump is connected to the air inlet pipe of the low-temperature liquid nitrogen bottle through an air pipe. The above technical solution cannot realize in-situ observation of the deformation process of the specimen. Moreover, the direct use of liquid nitrogen to cool the specimen will cause the liquid nitrogen to enter the microscopic pores of the specimen, thereby introducing errors in the experimental results, which will have an adverse effect on the actual test results. Summary of the Invention

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

[0006] To achieve the above objectives, the present invention provides the following technical solutions: a split-Hopkinson pressure bar experimental system for low-temperature in-situ observation, comprising a cryogenic chamber, a refrigeration device, an incident rod, and a transmission rod, wherein both the incident rod and the transmission rod are provided with strain gauges, both strain gauges being electrically connected to a dynamic strain gauge, the cryogenic chamber comprising a housing, an internal channel disposed within the housing, and a coolant chamber formed between an inner surface of the housing and an outer surface of the internal channel;

[0007] The refrigeration equipment is used to cool the coolant, and the coolant circulates between the coolant chamber and the coolant tank through a pump and pipes;

[0008] The internal channel includes a longitudinal pipe, a transverse pipe, and a vertical pipe. The longitudinal pipe runs through the shell in the front-to-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 connected to the longitudinal pipe, and the top end of the vertical pipe is flush with the top surface of the shell.

[0009] A longitudinal partition is provided inside the longitudinal pipe so as to be longitudinally slidable. At least three test pieces are longitudinally equidistantly provided on the longitudinal partition. The longitudinal partition is moved longitudinally so that the test pieces can pass directly under the vertical pipe in sequence.

[0010] A high-speed camera is arranged at the top of the vertical pipe to photograph the test piece arranged between the incident rod and the transmission rod.

[0011] Preferably, a plurality of vertical partitions are fixedly mounted on the top of the longitudinal partition by mounting vertical bars;

[0012] The left and right sides of the longitudinal partition are in contact with the left and right side surfaces of the inner wall of the longitudinal pipe respectively;

[0013] 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 respectively contact the left side, right side and top side of the inner wall of the longitudinal pipe;

[0014] A test piece is set between every two adjacent vertical partitions, and the test piece is set on the top of the flexible rolled felt.

[0015] Preferably, the longitudinal partition divides the longitudinal duct into two parts, a lower chamber and an upper chamber, and the vertical partition is arranged in the upper chamber;

[0016] A first baffle is fixed at one end of the lower chamber and is sealed to the longitudinal pipe;

[0017] A first longitudinal slide is fixed inside the lower chamber, and the longitudinal partition can slide in the longitudinal direction through the first longitudinal slide;

[0018] A vertically slidable bracket is provided on the longitudinal partition, and a second longitudinal slide bar for supporting the bracket is also fixed inside the lower chamber;

[0019] The second longitudinal slide bar includes a horizontal slide bar; when the bottom end of the bracket contacts the horizontal slide bar, the test piece is lifted by the bracket to separate from the flexible rolled felt, and when the bracket moves to just below the vertical pipe, the test piece contacts the flexible rolled felt.

[0020] Preferably, the second longitudinal slide bar further includes a first inclined bar fixedly connected to one end of the horizontal slide bar.

[0021] Preferably, the top of the vertical pipe is provided with tempered glass;

[0022] The inlet and outlet of the upper chamber are both provided with heat-insulating components;

[0023] The inner diameter of the transverse pipe is slightly larger than the diameters of the incident rod and the transmission rod;

[0024] The second longitudinal sliding 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;

[0025] A second baffle sealed and connected to the longitudinal pipe is fixed at the other end of the lower chamber.

[0026] Preferably, the bracket includes two guide sleeves vertically penetrating the longitudinal partition, a vertical guide rod slidingly penetrating the guide sleeve, a longitudinal rod fixed to the top of the vertical guide rod by a fastener, and a transverse circular shaft fixed to both ends of the longitudinal rod;

[0027] Two guide sleeves are respectively arranged on the left and right sides of the flexible rolled felt;

[0028] The bottom end of the vertical guide rod is provided with a spherical bottom.

[0029] Preferably, a positioning frame is provided around the tempered glass, and an illumination light source is fixed on the top of the tempered glass.

[0030] Preferably, the heat-insulating component includes a heat-insulating door panel, a sliding sleeve fixedly connected to the heat-insulating door panel via a connecting plate, and a transverse shaft fixedly connected to the outer shell, and the sliding sleeve is slidably mounted on the transverse shaft.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention first uses a refrigerant to cool the internal channel, and then uses the low-temperature environment inside the internal channel to cool the specimen, thereby avoiding direct contact between the specimen and the refrigerant, preventing the refrigerant from entering the microscopic pores of the specimen, and reducing experimental errors; at the same time, the cooling process of the specimen is relatively slow, which is consistent with the cooling process of the specimen in the external natural environment, and effectively avoids the adverse effects of the sudden cooling of the specimen on the experimental results; then, through the provision of longitudinal partitions, at least three specimens can be cooled synchronously in the longitudinal pipeline, and the cooling consistency is good. More importantly, multiple specimens can be moved to the test position in turn by pushing the longitudinal partition, and the specimens located at the test position are all in the optimal experimental temperature state, which saves the cooling time of each specimen before the experiment and significantly improves the experimental efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the overall system structure of the present invention;

[0034] Figure 2 It is a schematic diagram of the refrigeration equipment of the present invention;

[0035] Figure 3 Schematic diagram of the structure of the low-temperature box, the incident rod and the transmission rod of the present invention;

[0036] Figure 4 Schematic diagram of the cross-sectional three-dimensional structure of the housing of the present invention;

[0037] Figure 5 Schematic diagram of the structure of the internal channel of the present invention;

[0038] Figure 6 Schematic diagram of the cross-sectional three-dimensional structure of the internal channel of the present invention;

[0039] Figure 7 Schematic diagram of the side cross-sectional structure of the cryogenic box of the present invention;

[0040] Figure 8 Schematic diagram of the structure of the test piece of the present invention inside the internal channel;

[0041] Figure 9 is a schematic structural diagram of the second longitudinal slider of the present invention;

[0042] Figure 10 It is a side view structural diagram of the longitudinal partition of the present invention;

[0043] Figure 11 Schematic diagram of the structure of the bracket of the present invention;

[0044] Figure 12 It is a schematic side cross-sectional structure diagram of the longitudinal partition and guide sleeve of the present invention.

[0045] In the picture:

[0046] 100. Low-temperature box; 1. Outer shell; 11. Outlet; 12. Inlet; 2. Internal passage; 21. Longitudinal duct; 211. Lower chamber; 212. Upper chamber; 2121. Inlet; 2122. Outlet; 213. First longitudinal slide; 214. Second longitudinal slide; 2141. Horizontal slide; 2142. First inclined slide; 2143. Second inclined slide; 215. First baffle; 216. Second baffle; 22. Horizontal duct; 23. Vertical pipe; 24. Longitudinal partition; 25. Vertical partition; 26. Vertical mounting bar; 27. Flexible rolled felt; 28. Bracket; 281. Vertical guide rod; 282. Guide sleeve; 283. Longitudinal rod; 284. Horizontal circular shaft; 285. Fastener; 286. Spherical bottom; 3. Coolant chamber; 4. Tempered glass; 41. Positioning frame; 42. Light source; 5. Insulation component; 51. Insulation door panel; 52. Connecting plate; 53. Horizontal shaft; 54. Sliding sleeve;

[0047] 200, incident rod;

[0048] 300, transmission rod;

[0049] 400, strain gauge;

[0050] 500, dynamic strain gauge;

[0051] 600, high-speed camera;

[0052] 700, refrigeration equipment; 701, compressor; 702, condenser; 703, expansion valve; 704, evaporator;

[0053] 800, pump;

[0054] 900, pipeline;

[0055] 1000, coolant tank;

[0056] 1100. Test piece. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0058] See also Figures 1-12 , the present invention provides a technical solution:

[0059] A split-type Hopkinson pressure bar experimental system for low-temperature in-situ observation includes a low-temperature box 100 and a refrigeration device 700, as well as an incident rod 200 and a transmission rod 300. Strain gauges 400 are provided on the incident rod 200 and the transmission rod 300. 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 described in detail here.

[0060] Unlike the prior art, the low-temperature box 100 in the technical solution of the present invention includes an outer shell 1, an internal channel 2 arranged inside the outer shell 1, and a refrigerant chamber 3 formed between the inner surface of the outer shell 1 and the outer surface of the internal channel 2; wherein, the outer shell 1 has a heat-insulating effect. For example, in some embodiments, the outer shell 1 includes an internal metal layer and an external heat-insulating layer to achieve a heat-insulating effect. In other embodiments, other heat-insulating structures can also be used to achieve the heat-insulating effect of the outer shell 1; the internal channel 2 can be made of stainless steel as a whole, and its function is to quickly transfer the temperature of the refrigerant inside the refrigerant chamber 3 to the inside of the internal channel 2, so as to cool the test piece 1100 inside the internal channel 2.

[0061] The refrigeration equipment 700 is used to cool the refrigerant, and the refrigerant circulates between the refrigerant chamber 3 and the refrigerant tank 1000 through the pump 800 and the pipeline 900. Furthermore, the shell 1 is connected to the pipeline 900 through the discharge port 11 and the inlet 12; specifically, the refrigeration equipment 700 includes a compressor 701, a condenser 702, an expansion valve 703 and an evaporator 704, wherein the evaporator 704 is used to absorb heat by evaporation to achieve the cooling of the refrigerant. The refrigeration principle of the refrigeration equipment 700 is the existing technology and will not be elaborated here.

[0062] The internal channel 2 includes a longitudinal pipe 21, a transverse pipe 22 and a vertical pipe 23. Here, for the convenience of understanding and description, the longitudinal direction of the longitudinal pipe 21 can be defined as the front-to-back direction of the shell 1, and the transverse direction of the transverse pipe 22 can be defined as the left-to-right direction of the shell 1. The longitudinal pipe 21 penetrates the shell 1 along the front-to-back direction, and the front and rear end faces of the longitudinal pipe 21 are respectively flush with the front and rear end faces of the shell 1. The two transverse pipes 22 are fixedly connected on the left and right sides of the longitudinal pipe 21. The incident rod 200 and the transmission rod 300 extend to the interior of the longitudinal pipe 21 through the two transverse pipes 22 respectively. The two separated end faces of the two transverse pipes 22 are respectively flush with the left and right side faces of the shell 1. The bottom end of the vertical pipe 23 is connected to the longitudinal pipe 21, and the top end of the vertical pipe 23 is flush with the top surface of the shell 1. In actual operation, the test piece 1100 passes through the longitudinal pipe 21 in the front-to-back direction.

[0063] Since there are errors in the Hopkinson pressure bar experiment, it is necessary to conduct three experiments on at least three specimens 1100 to reduce the experimental error and improve the accuracy of the experimental structure. Therefore, in the present technical solution, a longitudinal partition 24 is provided inside the longitudinal pipe 21 so as to be longitudinally slidable. At least three specimens 1100 are arranged on the longitudinal partition 24 at equal distances in the longitudinal direction. By moving the longitudinal partition 24 in the longitudinal direction, the specimens 1100 can pass directly under the vertical pipe 23 in sequence. For the convenience of description, the present technical solution is illustrated by taking three specimens 1100 as an example. Specifically, as shown in the figure, the three specimens 1100 are placed on the longitudinal partition 24 at equal distances, and the longitudinal partition 24 is pushed to the position as shown in the figure. Figure 10As shown in the position, the specimen 1100 at the rear is at the test position, and is clamped and positioned by the two incident rods 200 and the transmission rod 300. The test can be carried out when the temperature of the specimen 1100 drops to a predetermined temperature; the other two specimens 1100 are at the waiting position for testing. When the specimen 1100 at the rear completes the test, the specimen 1100 located in the middle of the three specimens 1100 can be pushed to the test position for a second test by pushing the longitudinal partition 24 backward. Since the three specimens 1100 are all located inside the longitudinal pipe 21 for synchronous cooling, when testing the specimen 1100 in the middle, it is possible to start quickly without waiting for the specimen 1100 to cool down. Similarly, the specimen 1100 located at the front can also be quickly tested without waiting for cooling down, thereby improving the overall work efficiency.

[0064] The high-speed camera 600 is disposed at the top of the vertical pipe 23 for photographing the test piece 1100 disposed between the incident rod 200 and the transmission rod 300 .

[0065] In the present technical solution, the longitudinal pipe 21 is set in the front-to-back direction because: since the entire housing 1 is in a horizontal state, and the test pieces 1100 are all cylindrical, and the test pieces 1100 need to be coaxial with the incident rod 200 and the transmission rod 300, the longitudinal pipes 21 set in the front and back directions can conveniently move multiple test pieces 1100 in sequence between the incident rod 200 and the transmission rod 300; the vertical pipe 23 is set in the vertical direction because: since the test pieces 1100 in the experiment need to be placed on the flexible rolled felt 27 (or other flexible support pads), and the vertical pipe 23 serves as a channel for the high-speed camera 600 to shoot the test pieces 1100, if it is designed in the front-to-back direction, then only the high-speed camera 600 can shoot the test pieces 1100. The cracking or explosion process of the specimen 1100 is filmed from the front or back, so the cracking or explosion process of the specimen 1100 filmed at this time will be affected by the flexible rolled felt 27, which is not conducive to improving the accuracy of in-situ observation. However, since the vertical pipe 23 in the present technical solution is set vertically, the high-speed camera 600 directly films the specimen 1100 from top to bottom. At this time, there are no obstructions such as the flexible rolled felt 27 on the front and back sides of the top position of the specimen 1100 facing the high-speed camera 600. Therefore, the cracking or explosion process of the specimen 1100 will not be affected by external objects. The cracking or explosion process of the specimen 1100 captured by the high-speed camera 600 is the most realistic picture, which improves the accuracy of in-situ observation.

[0066] In the above technical solution, first, the internal channel 2 is cooled by using a refrigerant, and then the low temperature environment inside the internal channel 2 is used to cool the specimen 1100, thereby avoiding direct contact between the specimen 1100 and the refrigerant, preventing the refrigerant from entering the microscopic pores of the specimen, and reducing experimental errors; at the same time, the cooling process of the specimen 1100 is relatively slow, which is consistent with the cooling process of the specimen 1100 in the external natural environment, effectively avoiding the adverse effects of the sudden cooling of the specimen 1100 on the experimental results; then, by setting the longitudinal partition 24, at least three specimens 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 specimens 1100 can be moved to the test position in turn, and the specimens 1100 located at the test position are all in the optimal experimental temperature state, which saves the cooling time of each specimen 1100 before the experiment, and significantly improves the experimental efficiency.

[0067] A plurality of vertical partitions 25 are fixedly mounted on the top of the longitudinal partition 24 via mounting vertical bars 26. In this embodiment, the mounting vertical bars 26 can be made of stainless steel, and the vertical partitions 25 can be made of plastic or rubber. The left and right sides of the longitudinal partitions 24 are in contact with the left and right side surfaces of the inner wall of the longitudinal pipe 21, respectively. The bottom ends of the vertical partitions 25 abut against the upper surface of the longitudinal partitions 24, and the left edge, right edge, and top edge of the vertical partitions 25 are in contact with the left side, right side, and top side surfaces of the inner wall of the longitudinal pipe 21, respectively. A test piece 1100 is set between every two adjacent vertical partitions 25, and the test piece 1100 is set on the top of the flexible rolled felt 27; the purpose of the above setting is to enable the two adjacent vertical partitions 25 to cooperate with the longitudinal partition 24 and the inner wall of the longitudinal pipe 21 to form a front-to-back, left-to-right and bottom direction to achieve sealing, leaving only the top to cooperate with the vertical pipe 23 for facilitating the shooting of the high-speed camera 600, so that the residue of each test piece 1100 after the test is completed can be stored separately to avoid the residue of the test piece 1100 from being mixed together.

[0068] The longitudinal partition 24 divides the longitudinal pipe 21 into two parts, a lower chamber 211 and an upper chamber 212. The vertical partition 25 is set in the upper chamber 212; a first baffle 215 sealed with the longitudinal pipe 21 is fixed at one end of the lower chamber 211, and the first baffle 215 is used to prevent the external environment from exchanging heat with the interior of the lower chamber 211 through one end of the lower chamber 211; a first longitudinal slide 213 is fixed inside the lower chamber 211, and the longitudinal partition 24 can slide longitudinally through the first longitudinal slide 213, and the first longitudinal slide 213 is used to support Longitudinal partition 24; a vertically sliding bracket 28 is provided on the longitudinal partition 24, and a second longitudinal slide 214 for supporting the bracket 28 is also fixed inside the lower chamber 211, and the second longitudinal slide 214 is used to limit the height position of the bracket 28; specifically, the second longitudinal slide 214 includes a horizontal slide 2141; when the bottom end of the bracket 28 contacts the horizontal slide 2141, the specimen 1100 is lifted by the bracket 28 to separate from the flexible rolled felt 27, and when the bracket 28 moves to directly below the vertical pipe 23, the specimen 1100 contacts the flexible rolled felt 27.

[0069] like Figure 10 As shown, when the bottom end of the bracket 28 contacts the horizontal slide bar 2141, the bracket 28 lifts the specimen 1100, so that the specimen 1100 is separated from the flexible rolled felt 27. At this time, the bracket 28 serves to limit the position of the specimen 1100 thereon, preventing the specimen 1100 from position deviation due to factors such as vibration or inertia, and is used to improve the coaxiality between the specimen 1100 and the incident rod 200 and the transmission rod 300.

[0070] Specifically, such as Figure 11 and Figure 12 As shown, the bracket 28 includes two guide sleeves 282 vertically passing through the longitudinal partition 24, a vertical guide rod 281 sliding through the guide sleeve 282, a longitudinal rod 283 fixed to the top of the vertical guide rod 281 by a fastener 285, and a horizontal circular shaft 284 fixed to both ends of the longitudinal rod 283. Each specimen 1100 is supported and limited by the four horizontal circular shafts 284. Under the action of the specimen 1100's own gravity, the specimen 1100 will roll to a state of contact with the four horizontal circular shafts 284, so that the position of the specimen 1100 in the front and rear directions is limited by the four horizontal circular shafts 284. Furthermore, the longitudinal rods 283 located on the left and right sides of the specimen 1100 can limit the left and right directions of the specimen 1100; the two guide sleeves 282 are respectively arranged on the left and right sides of the flexible rolled felt 27; the bottom end of the vertical guide rod 281 is provided with a spherical bottom 286, which can reduce the friction between the vertical guide rod 281 and the horizontal slide 2141.

[0071] Furthermore, the second longitudinal slide 214 also includes a first inclined bar 2142 fixedly connected to one end of the horizontal slide 2141. The first inclined bar 2142 is used to allow the first inclined bar 2142 to slowly descend, ensuring that the specimen 1100 can fall smoothly on the corresponding flexible rolled felt 27 to prevent the specimen 1100 from shifting.

[0072] The basic principle of the above technical solution is: when the spherical bottom 286 of the bracket 28 contacts the horizontal slide 2141, the horizontal slide 2141 will support the bracket 28 at the highest position. At this time, the test piece 1100 located on the bracket 28 will also be separated from the flexible rolled 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 and rear positions of the test piece 1100, and the two longitudinal rods 283 of the bracket 28 can limit the left and right directions of the test piece 1100; when the longitudinal partition 24 is pushed to move backward, the bracket 28 will move backward with the longitudinal partition 24. When the spherical bottom 286 at the bottom of the bracket 28 moves to the rear end of the horizontal slide 2141, as the longitudinal partition 24 continues to move backward, the spherical bottom 286 will It will directly transition to the first inclined bar 2142, and then as the first inclined bar 2142 gradually moves downward, the height of the bracket 28 will also gradually move downward, eventually causing the specimen 1100 to gradually move to the test position, and causing the specimen 1100 to contact the flexible rolled 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 in the test position. There is no need to make fine adjustments to the position of the specimen 1100 to carry out the test, which further improves the overall experimental efficiency. In addition, since the internal channel 2 is closed, there is no need to adjust the position of the specimen 1100, which also brings convenience to the entire experimental process.

[0073] A tempered glass 4 is provided on the top of the vertical pipe 23. 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 a good thermal insulation 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. 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 clearer pictures; the entrance 2121 and the exit 2122 of the upper chamber 212 are both provided with insulation components 5. The heat-insulating component 5 includes a heat-insulating door panel 51, a sliding sleeve 54 fixedly connected to the heat-insulating door panel 51 via a connecting plate 52, and a transverse shaft 53 fixedly connected to the housing 1. The transverse shaft 53 can be a splined shaft, and the sliding sleeve 54 can be a splined sleeve to prevent the sliding sleeve 54 from rotating on the transverse shaft 53, ensuring that the heat-insulating door panel 51 can block the inlet 2121 and the outlet 2122. The sliding sleeve 54 is slidably mounted on the transverse shaft 53. The heat-insulating door panel 51 can move laterally along the axial direction of the transverse shaft 53 to open or close the inlet 2121 and the outlet 2122 of the upper chamber 212.

[0074] 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 inner diameter of the transverse pipe 22 is within 1 mm from the diameters of the incident rod 200 and the transmission rod 300, which has a heat preservation effect.

[0075] The second longitudinal slide 214 also includes a second inclined bar 2143 fixedly connected to the first inclined bar 2142. The first inclined bar 2142 and the second inclined bar 2143 are arranged in a V shape, and the connection position of the first inclined bar 2142 and the second inclined bar 2143 is located directly below the vertical pipe 23; the other end of the lower chamber 211 is fixed with a second baffle 216 sealedly connected to the longitudinal pipe 21; the second inclined bar 2143 is arranged to enable the bracket 28 to rise to the highest position along the second inclined bar 2143, ensuring that the bracket 28 can pass through the outlet 2122 smoothly. 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 interior of the lower chamber 211 through the other end of the lower chamber 211; that is, the second inclined bar 2143 cooperates with the second baffle 216, the first baffle 215 and the longitudinal partition 24 to achieve full closure of the lower chamber 211.

[0076] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the 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 cryogenic chamber and refrigeration equipment, an incident bar, and a transmission bar, each of which is provided with a strain gauge, both of which are electrically connected to a dynamic strain gauge, characterized by: The cryogenic box includes an outer shell, an inner channel arranged inside the outer shell, and a coolant chamber formed between the inner surface of the outer shell and the outer surface of the inner channel; The refrigeration equipment 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. The longitudinal pipe runs through the shell in the front-to-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 connected to the longitudinal pipe, and the top end of the vertical pipe is flush with the top surface of the shell. A longitudinal partition is provided inside the longitudinal pipe so as to be longitudinally slidable. At least three test pieces are longitudinally equidistantly provided on the longitudinal partition. The longitudinal partition is moved longitudinally so that the test pieces can pass directly under the vertical pipe in sequence. A high-speed camera is set at the top of the vertical pipe to shoot the test piece set between the incident rod and the transmission rod; A number of vertical partitions are fixedly installed on the top of the longitudinal partitions by installing vertical bars; The left and right sides of the longitudinal partition are in contact with the left and right side surfaces of the inner wall of the longitudinal pipe respectively; 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 respectively contact the left side, right side and top side of the inner wall of the longitudinal pipe; A test piece is set between every two adjacent vertical partitions, and the test piece is set on the top of the flexible rolled felt; The longitudinal partition divides the longitudinal pipe into two parts: a lower chamber and an upper chamber, and the vertical partition is set in the upper chamber; A first baffle is fixed at one end of the lower chamber and is sealed to the longitudinal pipe; A first longitudinal slide is fixed inside the lower chamber, and the longitudinal partition can slide in the longitudinal direction through the first longitudinal slide; A vertically slidable bracket is provided 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 test piece is lifted by the bracket to separate from the flexible rolled felt, and when the bracket moves to just below the vertical pipe, the test piece contacts the flexible rolled felt.

2. The split-Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 1, characterized in that: The second longitudinal slide bar further includes a first inclined bar fixedly connected to one end of the horizontal slide bar.

3. The split-Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 2, characterized in that: The top of the vertical pipe is provided with tempered glass; The inlet and outlet of the upper chamber are both provided with heat-insulating components; The inner diameter of the transverse pipe is slightly larger than the diameters of the incident rod and the transmission rod; The second longitudinal sliding 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 sealed and connected to the longitudinal pipe is fixed at the other end of the lower chamber.

4. The split-Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 3, characterized in that: The bracket includes two guide sleeves vertically penetrating the longitudinal partitions, a vertical guide rod slidingly penetrating the guide sleeves, a longitudinal rod fixed to the top of the vertical guide rod by fasteners, and a transverse circular shaft fixed to both ends of the longitudinal rod; Two guide sleeves are respectively arranged on the left and right sides of the flexible rolled felt; The bottom end of the vertical guide rod is provided with a spherical bottom.

5. The split-Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 3, characterized in that: Positioning frames are arranged around the tempered glass, and a lighting source is fixed on the top of the tempered glass.

6. The split-Hopkinson pressure bar experimental system for low-temperature in-situ observation according to claim 3, characterized in that: The heat-insulating component comprises a heat-insulating door panel, a sliding sleeve fixedly connected to the heat-insulating door panel via a connecting plate, and a transverse shaft fixedly connected to the outer shell, wherein the sliding sleeve is arranged on the transverse shaft.

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