Low-temperature mechanical testing device

Abstract

The invention provides a low-temperature mechanical testing device, and belongs to the field of low-temperature mechanics, and the low-temperature mechanical testing device comprises a shell, a sealing assembly, a fixing assembly, a temperature control device, a driving device and an observation device. The shell is provided with a heat insulation cavity and two openings communicated with the heat insulation cavity; the sealing assembly comprises two sealing pieces arranged corresponding to the two openings respectively, preformed holes and cooling channels are formed in the sealing pieces, the preformed holes communicate with the heat insulation cavity, and the cooling channels are arranged corresponding to the inner walls of the preformed holes; the fixing assembly comprises a force applying part and a fixing part, the force applying part is movably arranged in the preformed hole of one sealing piece, and the fixing part is arranged in the preformed hole of the other sealing piece; the temperature control device is arranged in the heat insulation cavity; the driving device is connected with the force application part; the observation device is arranged in the heat insulation cavity. According to the invention, external heat transferred to a test area can be reduced, the stability of a low-temperature environment is improved, and the accuracy of a test result is improved.

Description

Technical Field

[0001] This application relates to the field of low-temperature mechanical testing technology, specifically to a low-temperature mechanical testing device. Background Technology

[0002] In projects such as cold-region engineering, underground liquefied natural gas (LNG) storage facilities, and polar resource development, rock masses are subjected to prolonged low-temperature or even ultra-low-temperature environments. The dynamic loads generated by engineering activities such as blasting and mechanical excavation, coupled with these low-temperature environments, pose a severe challenge to the stability of the rock mass. Therefore, studying the dynamic mechanical behavior of rock materials at low temperatures is crucial.

[0003] However, in related technologies, existing low-temperature mechanical testing devices, when combining low-temperature environment with mechanical loading, cause external heat to easily transfer to the test area, making it difficult to maintain a stable low-temperature environment and affecting the accuracy of test results. Summary of the Invention

[0004] In view of the technical problems existing in the background art, this application provides a low-temperature mechanical testing device, which can reduce the transfer of external heat to the test area, improve the stability of the low-temperature environment, and thus improve the accuracy of the test results.

[0005] This application provides a low-temperature mechanical testing device, including: The shell has a heat insulation cavity and two openings communicating with the heat insulation cavity; The sealing assembly includes two sealing elements respectively provided for two openings. The sealing elements have reserved holes and cooling channels formed inside. The reserved holes are connected to the heat insulation cavity, and the cooling channels are provided corresponding to the inner wall of the reserved holes. The fixing component includes a force-applying part and a fixing part. The force-applying part is movably disposed in a reserved hole of one sealing element, and the fixing part is disposed in a reserved hole of another sealing element. The force-applying part and the fixing part are disposed opposite to each other for clamping the sample to be tested. A temperature control device is installed in the insulation cavity to regulate the temperature inside the insulation cavity; A driving device, connected to the force-applying part, is used to drive the force-applying part to move closer to or away from the fixing part, so as to apply pressure to the sample to be tested held between the force-applying part and the fixing part; and, The observation device, located in the heat-insulated cavity, is used for optical detection of the sample to be tested.

[0006] Furthermore, the sealing part includes a first connecting part, a second connecting part, and a cooling part. The first connecting part has a first opening, the second connecting part has a second opening, the cooling part has a through hole, and a cooling channel is arranged around the inner wall of the through hole. The first opening and the second opening together with the through hole define a reserved hole.

[0007] Furthermore, the first connecting part, the second connecting part, and the cooling part are separately arranged.

[0008] Furthermore, the two ends of the cooling section are respectively fitted onto the first opening and the second opening, and fasteners are provided between the first connecting part and the second connecting part.

[0009] Furthermore, a sealing element is provided in the reserved hole of the first connecting part, and the first connecting part is located in the opening.

[0010] Furthermore, the housing is provided with a light-transmitting part, which includes a substrate and a conductive film, with the conductive film disposed on the substrate.

[0011] Furthermore, the substrate includes two light-transmitting layers spaced apart, and a conductive film is disposed on the side of the light-transmitting layer that contacts the heat insulation cavity.

[0012] Furthermore, the temperature control device includes a delivery pipe that connects the insulation cavity to the external medium storage device.

[0013] Furthermore, the housing also includes an airflow channel that communicates with the insulation cavity.

[0014] Furthermore, the temperature control device also includes a temperature sensor and an electromagnetic distribution valve. The temperature sensor is located in the heat insulation cavity; the electromagnetic distribution valve is located in the delivery pipeline and is electrically connected to the temperature sensor.

[0015] The beneficial effects of this invention are: In the technical solution of this invention, the cooling channel can cool the inner wall of the pre-drilled hole. When the force-applying part or the fixing part contacts the inner wall of the pre-drilled hole, the cooling medium in the cooling channel can carry away the heat from the contact area, thereby reducing the temperature difference between the external environment and the insulation cavity, and reducing the amount of heat transfer and the heat transfer rate. That is, it reduces the transfer of external heat to the test area, improves the stability of the low-temperature environment, and thus improves the accuracy of the test results.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0018] Figure 1This is a partial structural schematic diagram of the low-temperature mechanical testing device in the embodiments of this application; Figure 2 This is a schematic diagram of the sealing assembly of the low-temperature mechanical testing device in the embodiments of this application; Figure 3 This is a schematic diagram of the drive device of the low-temperature mechanical testing device in the embodiments of this application; Figure 4 This is a schematic diagram of the temperature control device of the low-temperature mechanical testing device in the embodiments of this application; Figure 5 This is a schematic diagram of the low-temperature mechanical testing device in the embodiments of this application.

[0019] Explanation of reference numerals in the attached figures: 100. Low-temperature mechanical testing device; 1. Shell; 11. Insulation cavity; 12. Airflow channel; 2. Sealing assembly; 21. Seal; 211. Reserved hole; 212. First connecting part; 213. Second connecting part; 214. Cooling part; 22. Fastener; 23. Sealing element; 3. Fixing component; 31. Force-applying part; 32. Fixing part; 4. Temperature control device; 41. Delivery pipeline; 42. Temperature sensor; 43. Solenoid distribution valve; 5. Driving device; 6. Observation device. Detailed Implementation

[0020] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0022] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0025] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0026] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0027] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0028] In projects such as cold-region engineering, underground liquefied natural gas (LNG) storage facilities, and polar resource development, rock masses are subjected to prolonged low-temperature or even ultra-low-temperature environments. The dynamic loads generated by engineering activities such as blasting and mechanical excavation, coupled with these low-temperature environments, pose a severe challenge to the stability of the rock mass. Therefore, studying the dynamic mechanical behavior of rock materials at low temperatures is crucial.

[0029] However, in related technologies, the existing low-temperature mechanical testing device 100, when combining low-temperature environment with mechanical loading, causes external heat to be easily transferred to the test area, making it difficult to maintain a stable low-temperature environment and affecting the accuracy of the test results.

[0030] like Figure 1 , Figure 2 and Figure 5 As shown, in order to solve the above-mentioned technical problems, this application provides a low-temperature mechanical testing device 100, including a housing 1, a sealing component 2, a fixing component 3, a temperature control device 4, a driving device 5, and an observation device 6. The housing 1 has a heat insulation cavity 11 and two openings communicating with the heat insulation cavity 11; the sealing assembly 2 includes two sealing members 21 respectively corresponding to the two openings, and the sealing member 21 has a reserved hole 211 and a cooling channel formed inside. The reserved hole 211 communicates with the heat insulation cavity 11, and the cooling channel is provided corresponding to the inner wall of the reserved hole 211; the fixing assembly 3 includes a force-applying part 31 and a fixing part 32. The force-applying part 31 is movably disposed in the reserved hole 211 of one sealing member 21, and the fixing part 32 is disposed in the reserved hole 211 of the other sealing member 21. The force-applying part 31 and the fixing part 32 are disposed opposite to each other for clamping the sample to be tested; the temperature control device 4 is disposed in the heat insulation cavity 11 for adjusting the temperature inside the heat insulation cavity 11; the driving device 5 is connected to the force-applying part 31 for driving the force-applying part 31 to move closer to or away from the fixing part 32 to apply pressure to the sample to be tested clamped between the force-applying part 31 and the fixing part 32; the observation device 6 is disposed in the heat insulation cavity 11 for optical detection of the sample to be tested.

[0031] In the technical solution of this invention, the cooling channel can cool the inner wall of the reserved hole 211. When the force-applying part 31 or the fixing part 32 comes into contact with the inner wall of the reserved hole 211, the cooling medium in the cooling channel can carry away the heat in the contact area, thereby reducing the temperature difference between the external environment and the insulation cavity 11, and reducing the amount of heat transfer and the heat transfer rate. That is, it reduces the transfer of external heat to the test area, improves the stability of the low-temperature environment, and thus improves the accuracy of the test results.

[0032] It can be explained that the shell 1 refers to the main structure used to form the heat insulation cavity 11. Its material can be selected from materials with good heat insulation performance, such as polyurethane foam, vacuum insulation board, stainless steel inner liner, vacuum insulation layer, etc., to reduce heat exchange between the inside and outside of the heat insulation cavity 11.

[0033] It can be explained that the reserved hole 211 refers to the space through which the force-applying part 31 or the fixing part 32 can pass, allowing the force-applying part 31 and the fixing part 32 to extend into the heat insulation cavity 11 to clamp the sample to be tested. The cooling channel refers to the space through which a cooling medium (such as liquid nitrogen, cooling water, cryogenic gas, etc., the specific selection can be made according to different test requirements) can be introduced. The flow of the cooling medium absorbs and carries away the heat transferred from the inner wall of the reserved hole 211, thereby reducing the temperature of the inner wall of the reserved hole 211 and further preventing external heat from being transferred into the heat insulation cavity 11 through the contact part between the force-applying part 31 or the fixing part 32 and the inner wall of the reserved hole 211.

[0034] It can be noted that the force-applying part 31 and the fixing part 32 are components used to directly contact the sample under test and apply clamping force. Their materials can be selected from high-strength, low-thermal-conductivity materials according to testing requirements. Specifically, in one embodiment, the fixing component 3 adopts a split Hopkinson bar, which consists of an incident rod, a transmission rod, and an absorption rod. This allows for the dynamic mechanical property testing of brittle materials such as rocks under low-temperature environments, obtaining parameters such as impact compressive strength, elastic modulus, and strain rate effect. The incident rod constitutes the force-applying part, while the transmission rod and absorption rod constitute the fixing part 32. Furthermore, it is worth mentioning that in one embodiment, strain gauges are integrated inside the force-applying part 31 and the fixing part 32. The strain gauges can monitor the strain changes of the sample under test in real time during the force application process, providing crucial data support for analyzing its mechanical properties. The strain gauges are connected to an external data acquisition system via wires, enabling the conversion of mechanical signals into electrical signals for recording and analysis.

[0035] It can be explained that the temperature control device 4 refers to a system used to precisely control and maintain the temperature inside the insulation cavity 11. It can be adjusted according to different test temperature requirements by setting up a cooling unit and a heating unit to simulate different low temperature environments.

[0036] It can be explained that, for example Figure 3 As shown, the driving device 5 refers to the mechanism that provides power to the force-applying part 31 to load the sample to be tested. It can be driven by hydraulic pressure, pneumatic pressure, or electric motor. Specifically, in one embodiment, the driving device 5 includes an air tank, a high-pressure air chamber, a punch, and an impact velocity detector. The high-pressure air chamber is openable and closable and communicates with the air tank and the punch. The high-pressure air chamber is filled with air through the air tank. When a preset pressure is reached, the punch is released, and the punch strikes the force-applying part 31 (such as an incident rod), thereby realizing dynamic impact loading on the sample. The impact velocity detector can monitor the speed of the punch in real time to accurately control the loading rate.

[0037] It can be explained that the observation device 6 refers to a device used to observe and record in real time the surface morphology changes, crack propagation paths, and failure modes of the sample under test during the testing process. Specifically, in one embodiment, the observation device 6 includes a high-speed camera and a cold light source. The cold light source provides sufficient and stable illumination to the heat insulation cavity 11, avoiding interference from the low-temperature environment caused by the heating of traditional light sources. The high-speed camera can clearly capture the instantaneous changes of the sample during the dynamic loading process at a shooting speed of thousands or even tens of thousands of frames per second, providing intuitive image data for subsequent analysis of the damage evolution law and mechanical response mechanism of the sample.

[0038] Furthermore, it is worth mentioning that a central system controller can be set up, which is electrically connected to multiple electronic devices to achieve automated control and data acquisition of the entire testing process. For example, the central system controller can be electrically connected to the drive device 5 and the observation device 6 to synchronously trigger their operation, thereby accurately capturing the results of the sample under test at the moment of impact loading. In addition, mechanical waveforms (such as strain gauges) and high-speed image streams (such as high-speed cameras) can be acquired simultaneously to improve the accuracy of the test data.

[0039] Furthermore, in some embodiments, the sealing part includes a first connecting part 212, a second connecting part 213, and a cooling part 214. The first connecting part 212 has a first opening, the second connecting part 213 has a second opening, the cooling part 214 has a through hole, and a cooling channel is arranged around the inner wall of the through hole. The first opening and the second opening together with the through hole define a reserved hole 211.

[0040] In this embodiment, the sealing component 2 is connected to the housing 1 via the first connecting part 212 and the driving device 5 via the second sealing part, thus achieving stable assembly of the sealing component 2 with the housing 1 and the driving device 5. The cooling part 214 serves as a support for the cooling channel structure, thereby enabling connection with the force-applying part 31 or the fixing part 32.

[0041] It is understandable that the first connecting part 212, the second connecting part 213 and the cooling part 214 can be integrally set and manufactured by injection molding, casting and other methods to simplify the assembly process and improve the sealing and structural strength of the overall structure.

[0042] Furthermore, in some embodiments, the first connecting portion 212, the second connecting portion 213, and the cooling portion 214 are separately provided.

[0043] In this embodiment, the separate configuration facilitates the individual processing, assembly, and maintenance of each component. For example, when the cooling section 214 is damaged or needs to be replaced with a cooling channel of different specifications to meet different cooling requirements, the cooling section 214 can be disassembled and replaced separately without replacing the entire seal 21, thus reducing maintenance costs and difficulty.

[0044] It is understandable that the separate configuration can be achieved in a variety of ways, such as by assembling the first connecting part 212, the second connecting part 213 and the cooling part 214 into one unit through detachable connection methods such as bolt connection, snap connection or flange connection.

[0045] Furthermore, in some embodiments, the two ends of the cooling part 214 are respectively fitted onto the first opening and the second opening, and a fastener 22 is provided between the first connecting part 212 and the second connecting part 213.

[0046] In this embodiment, a nested assembly structure is formed by fitting the two ends of the cooling part 214 into the first opening of the first connecting part 212 and the second opening of the second connecting part 213, respectively. This structure effectively ensures the coaxiality between the cooling part 214 and the first connecting part 212 and the second connecting part 213, ensuring that the force-applying part 31 or the fixing part 32 can smoothly pass through the reserved hole 211. At the same time, a fastener 22, such as a combination of bolts, screws and nuts, is provided between the first connecting part 212 and the second connecting part 213. By tightening the fastener 22, the first connecting part 212, the cooling part 214 and the second connecting part 213 can be tightly clamped and fixed together, thereby further improving the overall structural stability and connection strength of the sealing assembly 2.

[0047] Furthermore, in some embodiments, a sealing element 23 is provided in the reserved hole 211 of the first connecting part 212, and the first connecting part 212 is provided in the opening.

[0048] In this embodiment, the sealing element 23 further enhances the sealing performance between the sealing assembly 2 and the housing 1. For example, the sealing element 23 can be made of a material that is resistant to low temperatures and has good elasticity, such as fluororubber or silicone rubber. Simultaneously, because the sealing element 23 is located close to the cooling channel, it reduces the risk of hardening and failure due to prolonged exposure to extreme low temperatures, thus extending its service life.

[0049] Understandably, the light-transmitting part can be made of materials with high light transmittance and good heat insulation properties, such as glass or polytetrafluoroethylene. Furthermore, the size, location, and number of the light-transmitting part can be designed according to the installation location of the observation device 6 and the observation requirements to meet the needs of observation from different angles.

[0050] Furthermore, in some embodiments, the housing 1 is provided with a light-transmitting portion, which includes a substrate and a conductive film, with the conductive film disposed on the substrate.

[0051] In this embodiment, by setting a conductive film on the substrate surface, when the temperature inside the insulation cavity 11 drops sharply during the test, the water vapor in the insulation cavity 11 is likely to condense into frost or fog on the surface of the light-transmitting part. The conductive film generates heat after being energized, reducing the condensation of water vapor on its surface. This effectively prevents frost or fogging from forming on the substrate surface in low-temperature environments, thereby ensuring good light transmittance of the light-transmitting part.

[0052] Specifically, in one embodiment, the conductive film can be made of transparent conductive materials such as ITO (indium tin oxide) film, which not only has good electrical conductivity and heating performance, but also ensures high visible light transmittance and will not obstruct the observation field. At the same time, the heating power of the conductive film can be adjusted according to the temperature and humidity of the actual use environment to achieve the best anti-frost and anti-fogging effect.

[0053] Furthermore, in some embodiments, the substrate includes two light-transmitting layers spaced apart, and a conductive film is disposed on the side of the light-transmitting layer that contacts the heat insulation cavity 11.

[0054] In this embodiment, two spaced-apart light-transmitting layers can form an air insulation layer or a vacuum layer, reducing heat exchange between the inside and outside of the insulation cavity 11, thereby improving the heat insulation performance of the light-transmitting part and helping to maintain the temperature stability of the insulation cavity 11. A conductive film is disposed on the side of the light-transmitting layer that contacts the insulation cavity 11, i.e., the conductive film is located inside the insulation cavity 11. In this way, when the conductive film is energized, it can directly act on the fogged or frosted areas, facilitating rapid removal of fog and frost, and ensuring timely and clear observation.

[0055] Furthermore, in some embodiments, the temperature control device 4 includes a delivery pipe 41 that connects the heat insulation cavity 11 to the external medium storage.

[0056] In this embodiment, the low-temperature medium (such as liquid nitrogen, liquid carbon dioxide, etc.) in the external medium storage can be transported to the heat insulation cavity 11 through the transport pipe 41, or the low-temperature medium in the heat insulation cavity 11 can be discharged and a higher temperature medium can be introduced when the temperature needs to be raised, thereby realizing the rapid adjustment of the temperature in the heat insulation cavity 11.

[0057] like Figure 1 As shown, in some embodiments, the housing 1 further includes an airflow channel 12 communicating with the heat insulation cavity 11.

[0058] In this embodiment, the airflow channel 12 enables the circulation and replacement of gas within the insulation cavity 11. For example, before the test begins, a dry inert gas (such as nitrogen) can be introduced into the insulation cavity 11 through the airflow channel 12 to expel humid air from the cavity and reduce fogging or frost formation. Alternatively, when the conductive film is in operation, the airflow channel 12 can be used to expel fog from the insulation cavity 11.

[0059] like Figure 4 As shown, in some embodiments, the temperature control device 4 further includes a temperature sensor 42 and an electromagnetic distribution valve 43. The temperature sensor 42 is disposed in the heat insulation cavity 11; the electromagnetic distribution valve 43 is disposed in the delivery pipe 41 and is electrically connected to the temperature sensor 42.

[0060] In this embodiment, the temperature inside the insulation cavity 11 is monitored in real time by a temperature sensor 42, and the temperature signal is transmitted to the electromagnetic distribution valve 43. Based on the received temperature signal, the electromagnetic distribution valve 43 precisely controls the flow rate and on / off state of the cryogenic medium in the delivery pipeline 41, thereby achieving closed-loop feedback regulation of the temperature inside the insulation cavity 11. For example, when the temperature sensor 42 detects that the temperature inside the insulation cavity 11 is higher than the preset target temperature, the electromagnetic distribution valve 43 opens wider, increasing the supply of the cryogenic medium and causing the temperature inside the insulation cavity 11 to quickly drop to the target value; conversely, when the temperature is lower than the target temperature, the electromagnetic distribution valve 43 closes or shuts off, reducing or stopping the supply of the cryogenic medium to prevent excessive temperature drop.

[0061] Specifically, in one embodiment, the temperature control device 4 further includes a PID controller, a proportional solenoid valve for the electromagnetic regulating valve, and a thermocouple for the temperature sensor 42, all three being electrically connected. With this configuration, the PID controller calculates the corresponding control signal based on the deviation between the actual temperature fed back by the temperature sensor 42 (thermocouple) and the preset target temperature, according to the PID control algorithm (proportional-integral-derivative control), and sends this signal to the electromagnetic distribution valve 43 (proportional regulating solenoid valve). This achieves continuous and precise regulation of the flow rate of the low-temperature medium, thereby stabilizing the temperature within the insulation cavity 11 near the preset target value, effectively improving the accuracy and stability of temperature control.

[0062] For example, the working process of the low-temperature mechanical testing device 100 of the present invention is as follows: Taking "Testing the dynamic Brazilian splitting strength of fractured red sandstone at -40℃" as an example, the operation process is explained in detail: S1. Process the red sandstone into a Φ50mm×25mm Brazilian disc and pre-fabricate a 20mm long fissure. Prepare speckle patterns: Spray with a waterproof white matte primer and cure at room temperature for 12 hours; use the matching black ink and random dot matrix mold to print speckles.

[0063] S2. The sample to be tested is placed into the insulation chamber and fixed by the force application part 31 and the fixing part 32. Cooling water is injected into the cooling channel (the temperature of the cooling water fluctuates around 5℃). The target temperature is set to -40.0℃ on the PID controller. The electromagnetic regulating valve is opened by the PID controller to rapidly cool the insulation chamber 11 to the pre-cooling temperature of -43.0℃ (3℃ lower than the target temperature). After reaching -43.0℃, the PID controller closes the electromagnetic regulating valve. Under the coupling effect of the conductive film and ambient heat leakage, the temperature inside the insulation chamber 11 rises. When the temperature rises to around -40.5℃, the PID controller starts the fine-tuning mode, intermittently opening the electromagnetic regulating valve to precisely stabilize the temperature at -40.0℃ ± 0.3℃ for several minutes, waiting for the loading command.

[0064] S3. Once the temperature stabilizes, set the high-speed camera parameters (frame rate: 15000fps). Trigger drive device 5 (pressure 0.5MPa) to start recording with the high-speed camera and activate the data acquisition card to record strain gauge signals.

[0065] S4. The strain waveform was processed using the three-wave method to calculate the dynamic splitting strength of the sample under test. DIC analysis: The image sequence was imported into DIC software to calculate the evolution image of the maximum principal strain field across the entire field. It can be clearly observed that the crack initiates from the crack tip 38 microseconds after loading, propagates along an inclined path at an average speed of about 380 m / s, and finally forms a tensile-shear composite failure fracture.

[0066] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A low-temperature mechanical testing device, characterized in that, include: The housing has a heat insulation cavity and two openings communicating with the heat insulation cavity; A sealing assembly includes two sealing elements respectively corresponding to the two openings. Each sealing element has a reserved hole and a cooling channel formed inside. The reserved hole communicates with the heat insulation cavity, and the cooling channel is provided corresponding to the inner wall of the reserved hole. A fixing component includes a force-applying part and a fixing part. The force-applying part is movably disposed in a reserved hole of one of the sealing elements, and the fixing part is disposed in a reserved hole of another of the sealing elements. The force-applying part and the fixing part are disposed opposite to each other for clamping the sample to be tested. A temperature control device is installed in the heat insulation cavity to regulate the temperature inside the heat insulation cavity; A driving device, connected to the force-applying part, is used to drive the force-applying part to move closer to or away from the fixing part in order to apply pressure to the sample to be tested held between the force-applying part and the fixing part; as well as, An observation device, located in the heat-insulating cavity, is used for optical detection of the sample to be tested.

2. The low-temperature mechanical testing device according to claim 1, characterized in that, The sealing part includes a first connecting part, a second connecting part, and a cooling part. The first connecting part has a first opening, the second connecting part has a second opening, the cooling part has a through hole, and the cooling channel is arranged around the inner wall of the through hole. The first opening and the second opening together with the through hole define the reserved hole.

3. The low-temperature mechanical testing device according to claim 2, characterized in that, The first connecting part, the second connecting part, and the cooling part are separately disposed.

4. The low-temperature mechanical testing device according to claim 3, characterized in that, The two ends of the cooling part are respectively fitted onto the first opening and the second opening, and fasteners are provided between the first connecting part and the second connecting part.

5. The low-temperature mechanical testing device according to claim 2, characterized in that, A sealing element is provided in the reserved hole of the first connecting part, and the first connecting part is located in the opening.

6. The low-temperature mechanical testing device according to claim 1, characterized in that, The housing is provided with a light-transmitting part, which includes a substrate and a conductive film, with the conductive film disposed on the substrate.

7. The low-temperature mechanical testing device according to claim 6, characterized in that, The substrate includes two light-transmitting layers spaced apart, and the conductive film is disposed on the side of the light-transmitting layer that contacts the heat insulation cavity.

8. The low-temperature mechanical testing device according to claim 1, characterized in that, The temperature control device includes a delivery pipe that connects the heat insulation cavity to the external medium storage device.

9. The low-temperature mechanical testing device according to claim 8, characterized in that, The housing also includes an airflow channel communicating with the heat insulation cavity.

10. The low-temperature mechanical testing device according to claim 8, characterized in that, The temperature control device further includes a temperature sensor and an electromagnetic distribution valve. The temperature sensor is disposed in the heat insulation cavity; the electromagnetic distribution valve is disposed in the delivery pipeline and is electrically connected to the temperature sensor.

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