Expansion ring test device based on carbon dioxide phase change and test method thereof

Abstract

The invention provides an expansion ring test device based on carbon dioxide phase change and a test method thereof. The expansion ring test device comprises a supporting seat, a confining pressure loading structure, a driving cylinder, a carbon dioxide filling pipe and an expansion ring sample, the driving cylinder is mounted on the supporting seat; the expansion ring sample is arranged on the driving cylinder in a sleeving manner and is positioned in an inner cavity of the confining pressure loading structure; the driving cylinder is sleeved with the confining pressure loading structure, and the confining pressure loading structure is used for applying confining pressure to the periphery of the driving cylinder; the carbon dioxide filling pipe is arranged in an inner cavity of the driving cylinder in a sealed mode, and the carbon dioxide filling pipe is heated to generate shock waves enabling the expansion ring sample to expand and break. According to the device and the method, the potential interference of a complex electromagnetic field environment on an experimental result is avoided, the application range is wide, experimental equipment is simplified, the energy consumption is reduced, the safety and the controllability of the experimental process are also remarkably improved, and the harm of shock waves and fragments generated by explosion on the experimental equipment and the surrounding environment is reduced.

Description

Technical Field

[0001] The present application relates to the field of material impact crushing, and in particular to an expansion ring test device and a test method thereof based on carbon dioxide phase change. Background Art

[0002] As a research focus of solid mechanics, the impact crushing of brittle materials has been widely used in many key fields such as mining, blasting, geotechnical engineering, aerospace and materials engineering. The expansion ring test has a simple structure and sufficient theoretical basis, and is the main method for studying the impact crushing characteristics of brittle materials. At present, the expansion ring test under impact loading mainly includes electromagnetic expansion ring, explosive expansion ring, hydraulic expansion ring and other types; among them, the electromagnetic expansion ring uses the Lorentz force as the driving force, and can accurately control the expansion strain rate. However, the prerequisite of this test method is that the expansion ring material needs to have good conductivity. The thermal softening effect generated by the large current during the driving process will significantly change the mechanical properties of the expansion ring, making it difficult for the test results to truly reflect the dynamic behavior of the material at room temperature, and the expansion strain rate that can be achieved is low, which is difficult to apply to materials with low conductivity such as rocks and ceramics.

[0003] The explosive expansion ring uses the shock wave generated by the explosive as the driving force, which can easily achieve a high strain rate expansion, and has no special requirements for the conductivity and other physical properties of the expansion ring material, which increases the applicability of the expansion ring test. At the same time, since the energy is released quickly and concentratedly during the explosion, the temperature rise phenomenon is not obvious, which reduces the interference of thermal effects on the test results. However, the propagation characteristics of the shock wave may affect the one-dimensional stress state of the expansion ring test, causing the test results to deviate from the theoretical model. In addition, the uncertainty of the explosion process increases the difficulty of precise control of the strain rate, which affects the repeatability and reliability of the test results. In addition, explosion tests usually involve the approval, storage, transportation, use and post-test safety handling of explosives, which increases the cost and complexity of the test and is difficult to promote to civilian scientific research institutions.

[0004] The hydraulic expansion ring utilizes the nearly incompressible physical property of liquid. By quickly impacting the piston from the outside, the liquid in the piston cylinder expands at a high speed in a short period of time, achieving dynamic tensile fracture of the expansion ring, so that the strain rate level it can reach is relatively low. The flow and pressure transmission of hydraulic pressure in the pipeline requires a certain amount of time, resulting in a relatively slow loading response speed of the hydraulic system, which is not suitable for the application requirements of expansion rings in medium and high strain rates. Summary of the invention

[0005] One of the purposes of the present application is to provide an expansion ring test device and a test method based on carbon dioxide phase change. The impact pressure generated by the supercritical carbon dioxide phase change is used as an alternative source to traditional electromagnetic, explosive and hydraulic pressure, so as to realize dynamic expansion test research in a wide strain rate range of low, medium and high. At the same time, the device applies a uniform and controllable static confining pressure around the expansion ring through a confining pressure loading structure to simulate the ground stress environment of deep rocks and other materials, so that the test data obtained are more real and reliable.

[0006] The technical solution of this application is:

[0007] A carbon dioxide phase change-based expansion ring test device comprises a support seat, a confining pressure loading structure, a driving cylinder, a carbon dioxide filling tube and an expansion ring sample; the driving cylinder is mounted on the support seat; the expansion ring sample is sleeved on the driving cylinder and is located in the inner cavity of the confining pressure loading structure; the confining pressure loading structure is sleeved on the driving cylinder and is used to apply confining pressure to the periphery of the driving cylinder; the carbon dioxide filling tube is sealed in the inner cavity of the driving cylinder, and the carbon dioxide filling tube is heated to generate a shock wave that expands and breaks the expansion ring sample.

[0008] As a technical solution of the present application, a positioning groove with an upward opening is provided on the support seat, and the lower end of the driving cylinder is threadedly connected to the positioning groove.

[0009] As a technical solution of the present application, a lower end cover is provided on the inner bottom plate of the positioning groove, the bottom end of the driving cylinder abuts against the lower end cover, and an upper end cover is provided on the top cover.

[0010] As a technical solution of the present application, the support seat is made of low-elongation, high-strength steel material.

[0011] As a technical solution of the present application, a lower sealing cover is sealed on the bottom opening of the driving cylinder, and an upper sealing cover is sealed on the top opening; the carbon dioxide filling tube is arranged between the upper sealing cover and the lower sealing cover.

[0012] As a technical solution of the present application, the carbon dioxide filling tube includes a tube body, a heating tube and an electric lead; the heating tube is detachably arranged in the inner cavity of the tube body, and the heating tube is filled with a carbon dioxide heating agent; the tube body cavity is filled with liquid carbon dioxide; one end of the electric lead extends into the heating tube, and an electric ignition head is arranged on the end.

[0013] As a technical solution of the present application, the confining pressure loading structure includes a confining pressure chamber; the confining pressure chamber is sleeved on the driving cylinder, and a water pump is provided at the lower part of one side; the water pump is connected to a high-frequency response water transmission pipeline, and the water outlet of the high-frequency response water transmission pipeline is connected to the inner cavity of the confining pressure loading structure; an observation window is provided in the middle part of one side of the confining pressure chamber.

[0014] As a technical solution of the present application, the confining pressure chamber is a pressure vessel made of high-strength alloy steel, and a cover plate is provided on the top of the confining pressure chamber.

[0015] As a technical solution of the present application, the acoustic impedance of the driving cylinder is the same as the acoustic impedance of the expansion ring sample.

[0016] As a technical solution of the present application, the carbon dioxide filling tube, the expansion ring sample and the driving cylinder are coaxially arranged.

[0017] As a technical solution of the present application, the outer side of the carbon dioxide filling tube is in close contact with the inner side of the driving cylinder.

[0018] As a technical solution of the present application, it also includes a monitoring component, which includes a full-digital dynamic servo sensor, a high-speed camera, a laser velocimeter, a plurality of strain gauges and a computer; the full-digital dynamic servo sensor is arranged in the confining pressure loading structure; the high-speed camera is arranged on the confining pressure loading structure, and is used to shoot the dynamic fragmentation process of the expansion ring specimen; the laser velocimeter is arranged in the confining pressure loading structure and is aligned with the axial center position of the expansion ring specimen, and is used to measure the radial expansion speed of the expansion ring specimen; the plurality of strain gauges are respectively arranged at intervals on the expansion ring specimen, and are used to collect the strain signal of the expansion ring specimen during the test; the computer is electrically connected to the strain gauge, the full-digital dynamic servo sensor, the high-speed camera and the laser velocimeter respectively.

[0019] A test method for the expansion ring test device based on carbon dioxide phase change as described above comprises the following steps:

[0020] S1, making the material to be studied into a standard expansion ring specimen according to the test requirements; arranging a plurality of strain gauges on the outer surface of the expansion ring specimen to measure the strain signal of the expansion ring specimen during the test;

[0021] S2, placing the expansion ring sample in the confining pressure loading structure, placing the driving cylinder in the inner cavity of the expansion ring sample and closely attached to the inner circumferential wall of the expansion ring sample, placing the carbon dioxide filling tube in the inner cavity of the driving cylinder and closely attached to the inner circumferential wall of the driving cylinder; fixing a high-speed camera and a laser velocimeter on the confining pressure loading structure, and starting the computer to prepare for the test;

[0022] S3, applying corresponding confining pressure to the expansion ring specimen through the water pump on the confining pressure loading structure and the high-frequency response water transmission pipeline according to the test requirements;

[0023] S4, after the confining pressure loading is completed, the power supply is connected to the electric lead of the carbon dioxide filling tube to heat the liquid carbon dioxide in the carbon dioxide filling tube, and when the liquid carbon dioxide in the carbon dioxide filling tube absorbs heat, it instantly vaporizes and generates a shock wave to expand and break the expansion ring sample;

[0024] S5, cut off the power supply after the test.

[0025] Beneficial effects of this application:

[0026] In the expansion ring test device and test method based on carbon dioxide phase change of the present application, compared with electromagnetic drive, the present device and method avoid the potential interference of complex electromagnetic field environment on the experimental results by controlling the heating rate and loading amount of carbon dioxide, expand the range of applicable test materials, simplify the experimental equipment and reduce energy consumption; compared with explosion drive, the present device and method significantly improve the safety and controllability of the experimental process by controlling the heating rate and loading amount of carbon dioxide, and reduce the harm of shock waves and fragments generated by the explosion to the experimental equipment and the surrounding environment; and compared with hydraulic drive, it controls the amount of carbon dioxide heating agent and the amount of liquid carbon dioxide to achieve a higher response speed and pressure regulation accuracy, can more accurately simulate the crushing behavior of the expansion ring sample under dynamic loading conditions, and realize expansion tests of different pressures by controlling the heating rate and loading amount of carbon dioxide. In addition, the present device applies a uniform and controllable static confining pressure around the expansion ring sample through the initial static loading method of the confining pressure loading structure to simulate the ground stress environment of deep rock and other materials, so that the test results are more real and reliable. In addition, it uses the expansion force caused by carbon dioxide phase change technology to conduct dynamic expansion tests on expansion ring samples, which can more realistically simulate the dynamic tensile failure of materials in deep environments, thereby making the test results more realistic and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the implementation methods of the present application, the drawings required for use in the implementation methods will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A schematic diagram of an expansion ring test device and a test method based on carbon dioxide phase change provided in an embodiment of the present application;

[0029] Figure 2 A schematic diagram of an expansion ring sample provided in an embodiment of the present application;

[0030] Figure 3 A schematic diagram of a drive cylinder provided in an embodiment of the present application;

[0031] Figure 4 A schematic diagram of a carbon dioxide filling tube provided in an embodiment of the present application;

[0032] Figure 5 A schematic diagram of the confining pressure loading structure provided in an embodiment of the present application.

[0033] Icons: 1-support seat; 2-driving cylinder; 3-carbon dioxide filling tube; 4-expansion ring specimen; 5-lower end cover; 6-upper end cover; 7-lower sealing cover; 8-upper sealing cover; 9-tube body; 10-heating tube; 11-electric lead; 12-carbon dioxide heating agent; 13-liquid carbon dioxide; 14-electric ignition head; 15-confining pressure chamber; 16-water pump; 17-high-frequency response water transmission pipeline; 18-observation window; 19-strain gauge; 20-cover plate. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0036] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0037] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is usually placed when in use. These are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0038] In addition, in the present application, unless otherwise clearly specified and limited, the first feature being above or below the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, the first feature being above, above, and above the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being below, below, and below the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0039] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] Example:

[0042] Please refer to Figure 1 , with reference Figures 2 to 5The present application provides an expansion ring test device based on carbon dioxide phase change, which mainly includes a support seat 1, a confining pressure loading structure, a driving cylinder 2, a carbon dioxide filling tube 3, an expansion ring sample 4 and a monitoring component; wherein the driving cylinder 2 is installed on the support seat 1; at the same time, the expansion ring sample 4 is sleeved on the driving cylinder 2 and is in the inner cavity of the confining pressure loading structure; in addition, the confining pressure loading structure is sleeved on the driving cylinder 2, and is used to apply confining pressure to the surrounding of the driving cylinder 2; and the carbon dioxide filling tube 3 is sealed in the inner cavity of the driving cylinder 2, and the outer side of the carbon dioxide filling tube 3 is close to the inner side of the driving cylinder 2, and it is ensured that the carbon dioxide filling tube 3, the expansion ring sample 4 and the driving cylinder 2 are coaxially arranged, reducing the test error caused by the introduction of non-axial force or torque, and heating the carbon dioxide filling tube 3 to generate a shock wave that expands and breaks the expansion ring sample 4. In addition, the expansion ring sample 4 can be freely made of materials of different types and properties according to research needs, which broadens the range of materials for experimental research. In addition, the monitoring component is used to monitor the test process of the expansion ring sample 4.

[0043] Furthermore, a positioning groove with an upward opening and a threaded inner wall is provided on the support seat 1, and the lower end of the driving cylinder 2 is threadedly connected to the positioning groove. A lower end cover 5 is provided on the inner bottom plate of the positioning groove, the bottom end of the driving cylinder 2 abuts against the lower end cover 5, and an upper end cover 6 is provided on the top cover.

[0044] It should be noted that the support seat 1 can be made of low-elongation, high-strength steel materials, such as alloy steel, high-carbon steel and stainless steel, which can have little change in length or shape under long-term use or under heavy loads, which helps to maintain the geometric accuracy and stability of the support seat 1.

[0045] Furthermore, a lower sealing cover 7 is sealed and installed on the bottom opening of the driving cylinder 2, and an upper sealing cover 8 is sealed and installed on the top opening; the carbon dioxide filling tube 3 is arranged between the upper sealing cover 8 and the lower sealing cover 7. In addition, the carbon dioxide filling tube 3 includes a tube body 9, a heating tube 10 and an electric lead 11; the heating tube 10 is detachably arranged in the inner cavity of the tube body 9, and the heating tube 10 is filled with a carbon dioxide heating agent 12; the cavity of the tube body 9 is filled with liquid carbon dioxide 13; one end of the electric lead 11 extends into the heating tube 10, and an electric ignition head 14 is arranged on the end. During the test, the electric lead 11 is connected to the power supply, and the electric ignition head 14 acts on the carbon dioxide heating agent 12. The carbon dioxide heating agent 12 generates heat and transfers the heat to the liquid carbon dioxide 13 through the heating tube 10. The liquid carbon dioxide 13 absorbs a certain amount of heat and instantly vaporizes, generating an impact force to achieve the expansion and crushing of the expansion ring sample 4. After the test, the power supply is cut off in time.

[0046] By controlling the dosage of the carbon dioxide heating agent 12, the phase change temperature of the supercritical carbon dioxide can be controlled, different gas pressure loading can be achieved, and different expansion rate loading can be further achieved. By controlling the heating rate and loading amount of carbon dioxide, different gas pressures and different pressure increase rates can be achieved, and different expansion rates can be further obtained, and the potential interference of the complex electromagnetic field environment on the experimental results can be avoided, the range of applicable test materials can be expanded, the experimental equipment can be simplified, and energy consumption can be reduced; by controlling the heating rate and loading amount of carbon dioxide, the safety and controllability of the experimental process can be significantly improved, and the harm of the shock wave and fragments generated by the explosion to the experimental equipment and the surrounding environment can be reduced; it can achieve the effect of higher response speed and pressure regulation accuracy by controlling the dosage of the carbon dioxide heating agent 12 and the amount of liquid carbon dioxide 13, and can more accurately simulate the crushing behavior of the expansion ring sample 4 under dynamic loading conditions, and realize expansion tests of different pressures by controlling the heating rate and loading amount of carbon dioxide. Therefore, it uses the expansion force caused by the carbon dioxide phase change technology to perform a dynamic expansion test on the expansion ring sample 4, which can more realistically simulate the dynamic tensile failure of the material in the deep environment, and thus make the test results more real and reliable.

[0047] It should be noted that the phase change temperature (i.e., critical temperature) is fixed under standard conditions (about 31.1°C), but in fact, this critical temperature is not directly adjusted. Instead, the intensity of the phase change process and the generated gas pressure are controlled by controlling the filling amount of liquid carbon dioxide 13 and the dosage (heating rate) of the carbon dioxide heating agent 12. In this way, the magnitude and speed of change of the force acting on the expansion ring sample 4 can be flexibly adjusted to achieve different strain rate loading. Therefore, the device and experimental method in this application are applicable to expansion ring samples 4 of different materials. Whether it is metal, plastic or other materials, as long as they can withstand certain pressure and deformation, they can be studied by adjusting the strain rate, that is, they can be experimentally studied by the device and experimental method in this application.

[0048] It should be noted that the drive tube 2 is made of high-strength, corrosion-resistant stainless steel or alloy steel so that it can be kept intact as much as possible during the test, and the outer diameter of the drive tube 2 is 49-52mm, the inner diameter is 46-49mm, and the height is 10cm. In addition, the acoustic impedance of the drive tube 2 is the same as that of the expansion ring sample 4. The acoustic impedance characteristics of the drive tube 2 material are adjusted by heat treatment, surface treatment or chemical treatment to make its acoustic impedance closer to the acoustic impedance of the expansion ring sample 4; optimize the contact interface between the drive tube 2 and the expansion ring sample 4 to ensure that the two are closely fitted and reduce the influence of air gaps or impurities on the transmission of sound waves; ensure that the drive tube 2 and the expansion ring sample 4 are accurately matched in thickness to reduce the sound wave scattering and energy loss caused by size differences, reduce the reflection and energy loss of shock waves at the interface between the drive tube 2 and the expansion ring sample 4, so that the driving energy can be efficiently transferred to the expansion ring sample 4, thereby inducing and maintaining the one-dimensional stress state of the expansion ring sample 4.

[0049] After inserting the driving cylinder 2 into the positioning groove in the center of the support seat 1, the driving ring cylinder is firmly locked through the positioning groove to prevent it from falling off; the outer diameter of the driving cylinder 2 is close to the inner side of the expansion ring sample 4, and the lower sealing cover 7 and the upper sealing cover 8 are respectively installed on the upper and lower ends of the carbon dioxide filling tube 3, and the upper end cover 6 and the lower end cover 5 are respectively installed on the upper and lower ends of the driving cylinder 2 to reduce the leakage of carbon dioxide gas.

[0050] In addition, the confining pressure loading structure includes a confining pressure chamber 15; the confining pressure chamber 15 is a pressure vessel made of high-strength alloy steel, and a cover plate 20 is provided on the confining pressure chamber 15. The confining pressure chamber 15 is sleeved on the driving cylinder 2, and a water pump 16 is provided at the lower part of one side, and the water pump 16 is connected to a high-frequency response water transmission pipeline 17, and the water outlet of the high-frequency response water transmission pipeline 17 is connected to the inner cavity of the confining pressure loading structure; an observation window 18 is provided in the middle of one side of the confining pressure chamber 15, and a high-speed camera is arranged above the observation window 18 to observe the expansion and crushing of the expansion ring sample 4. During the test, the cover plate 20 of the confining pressure chamber 15 is opened to place the expansion ring sample 4, the driving cylinder 2 and the carbon dioxide filling tube 3; the inner diameter of the confining pressure chamber 15 is larger than the outer diameter of the expansion ring sample 4, so as to provide space for the expansion and crushing of the expansion ring sample 4. The confining pressure chamber 15 applies uniform stress to the expansion ring sample 4 through the water pump 16 and the high-frequency response water transmission pipeline 17, which can reach up to 20MPa. A sealing ring is provided at the connection between the confining pressure chamber 15 and the water pump 16. The water pump 16 is started and the pressure is gradually increased to make the pressure in the confining pressure chamber 15 reach a preset value.

[0051] Therefore, through the initial static loading mode of the confining pressure loading structure, a uniform and controllable static confining pressure is applied around the expansion ring sample 4 to simulate the ground stress environment of deep rock and other materials, so that the test results are more real and reliable.

[0052] It should be noted that the outer diameter of the expansion ring sample 4 is 52-55 mm, the inner diameter is 49-52 mm, and the height is 1.5-2 mm. Due to its structural characteristics, the expansion ring sample 4 has no end effect, and when the expansion ring sample 4 is thin, it maintains a nearly one-dimensional stress state during the expansion process.

[0053] In addition, the monitoring component includes a full-digital dynamic servo sensor, a high-speed camera, a laser velocimeter, a plurality of strain gauges 19 and a computer; wherein the full-digital dynamic servo sensor is arranged in the confining pressure loading structure to complete the loading of the confining pressure required for the test and dynamically regulate the confining pressure changes caused by the deformation of the expansion ring sample 4 during the experiment; at the same time, the high-speed camera is arranged on the confining pressure chamber 15 and is located above the observation window 18, which is used to shoot the dynamic fragmentation process of the expansion ring sample 4; in addition, the laser velocimeter is arranged in the confining pressure loading structure and is aligned with the axial center position of the expansion ring sample 4, which is used to measure the radial expansion speed of the expansion ring sample 4; and, a plurality of strain gauges 19 are arranged on the expansion ring sample 4 at intervals, which are used to collect the strain signals of the expansion ring sample 4 during the test. The strain gauges 19 can capture and record the tiny deformations of the expansion ring sample 4 during the expansion process in real time and accurately, and further analyze the mechanical properties of the expansion ring sample 4; the computer is electrically connected to the strain gauge 19, the full-digital dynamic servo sensor, the high-speed camera and the laser velocimeter respectively.

[0054] It should be noted that the supercritical carbon dioxide phase change is a process that can be precisely controlled by controlling parameters such as temperature and the volume of liquid carbon dioxide 13. By adjusting these parameters such as temperature and the volume of liquid carbon dioxide 13, the timing and intensity of the phase change can be precisely controlled to obtain various pressure levels from slight impact to strong impact, thereby meeting the test requirements at low, medium and high strain rates. In addition, the supercritical carbon dioxide phase change process has the characteristics of rapid response and concentrated energy release. At the moment of phase change, energy is quickly released, and the required strain rate can be reached in a short time, greatly reducing the time scale of the dynamic expansion test. At the same time, the supercritical carbon dioxide phase change technology has the advantages of environmental friendliness and high safety. No harmful substances will be produced or environmental pollution will be caused during the phase change process, which improves the safety of the test process. In addition, the device and method can be adapted to the dynamic expansion test research of different materials and structures. Whether it is metal, ceramic, rock or composite material, the phase change conditions can be adjusted by the device to generate suitable impact pressure for testing.

[0055] Furthermore, in this embodiment, a test method of the expansion ring test device based on the carbon dioxide phase change is also provided, comprising the following steps:

[0056] S1, the material to be studied is made into a standard expansion ring sample 4 according to the test requirements; a plurality of strain gauges 19 are arranged on the outer surface of the expansion ring sample 4 to measure the strain signal of the expansion ring sample 4 during the test;

[0057] S2, place the expansion ring sample 4 in the confining pressure loading structure, place the driving tube 2 in the inner cavity of the expansion ring sample 4 and close to the inner circumferential wall of the expansion ring sample 4, place the carbon dioxide filling tube 3 in the inner cavity of the driving tube 2 and close to the inner circumferential wall of the driving tube 2; fix the high-speed camera and laser velocimeter on the confining pressure loading structure, start the computer and prepare to start the test;

[0058] S3, according to the test requirements, the corresponding confining pressure is applied to the expansion ring sample 4 through the water pump 16 on the confining pressure loading structure and the high-frequency response water transmission pipeline 17;

[0059] S4, after the confining pressure loading is completed, the power supply is connected to the electric lead 11 of the carbon dioxide filling tube 3, and the liquid carbon dioxide 13 in the carbon dioxide filling tube 3 is heated. When the liquid carbon dioxide 13 in the carbon dioxide filling tube 3 absorbs heat, it instantly vaporizes and generates a shock wave to expand and break the expansion ring sample 4;

[0060] S5, cut off the power supply after the test.

[0061] In summary, in the expansion ring test device and test method based on carbon dioxide phase change of the present application, compared with electromagnetic drive, the present device and method avoid the potential interference of complex electromagnetic field environment on the experimental results by adjusting the filling amount and heating rate of liquid carbon dioxide 13, expand the range of applicable test materials, simplify the experimental equipment and reduce energy consumption; compared with explosion drive, the present device and method significantly improve the safety and controllability of the experimental process by controlling the heating rate and filling amount of carbon dioxide, and reduce the harm of shock waves and fragments generated by the explosion to the experimental equipment and the surrounding environment; and compared with hydraulic drive, it controls the amount of carbon dioxide heating agent 12 and the amount of liquid carbon dioxide 13 to achieve a higher response speed and pressure regulation accuracy, and can more accurately simulate the crushing behavior of the expansion ring sample 4 under dynamic loading conditions, and realize expansion tests of different pressures by controlling the heating rate and filling amount of carbon dioxide. In addition, the present device applies a uniform and controllable static confining pressure around the expansion ring sample 4 through the initial static loading method of the confining pressure loading structure to simulate the ground stress environment of deep rock and other materials, so that the test results are more real and reliable. Furthermore, the expansion force caused by the carbon dioxide phase change technology is used to perform a dynamic expansion test on the expansion ring sample 4, which can more realistically simulate the dynamic tensile failure of the material in a deep environment, thereby making the test results more realistic and reliable.

[0062] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An expansion ring test device based on carbon dioxide phase change, characterized in that: It includes a support seat, a confining pressure loading structure, a driving cylinder, a carbon dioxide filling tube and an expansion ring sample; the driving cylinder is installed on the support seat; the expansion ring sample is sleeved on the driving cylinder and is located in the inner cavity of the confining pressure loading structure; the confining pressure loading structure is sleeved on the driving cylinder and is used to apply confining pressure to the periphery of the driving cylinder; the carbon dioxide filling tube is sealed in the inner cavity of the driving cylinder, and the carbon dioxide filling tube is heated to generate a shock wave that expands and breaks the expansion ring sample.

2. The expansion ring test device based on carbon dioxide phase change according to claim 1 is characterized in that: The support seat is provided with a positioning groove with an opening facing upward, and the lower end of the driving cylinder is threadedly connected to the positioning groove.

3. The expansion ring test device based on carbon dioxide phase change according to claim 2 is characterized in that: A lower end cover is arranged on the inner bottom plate of the positioning groove, the bottom end of the driving cylinder abuts against the lower end cover, and an upper end cover is arranged on the top end cover.

4. The expansion ring test device based on carbon dioxide phase change according to claim 1 is characterized in that: The support seat is made of low-elongation, high-strength steel material.

5. The expansion ring test device based on carbon dioxide phase change according to claim 1 is characterized in that: A lower sealing cover is sealed on the bottom opening of the driving cylinder, and an upper sealing cover is sealed on the top opening; the carbon dioxide filling pipe is arranged between the upper sealing cover and the lower sealing cover.

6. The expansion ring test device based on carbon dioxide phase change according to claim 1 is characterized in that: The carbon dioxide filling tube includes a tube body, a heating tube and an electric lead; the heating tube is detachably arranged in the inner cavity of the tube body, and the heating tube is filled with a carbon dioxide heating agent; the tube body cavity is filled with liquid carbon dioxide; one end of the electric lead extends into the heating tube, and an electric ignition head is arranged on the end head.

7. The expansion ring test device based on carbon dioxide phase change and the test method thereof according to claim 1 are characterized in that: The confining pressure loading structure includes a confining pressure chamber; the confining pressure chamber is sleeved on the driving cylinder, and a water pump is provided at the lower part of one side; the water pump is connected to a high-frequency response water transmission pipeline, and the water outlet of the high-frequency response water transmission pipeline is connected to the inner cavity of the confining pressure loading structure; an observation window is provided in the middle part of one side of the confining pressure chamber.

8. The expansion ring test device based on carbon dioxide phase change and the test method thereof according to claim 7 are characterized in that: The confining pressure chamber is a pressure vessel made of high-strength alloy steel, and a cover plate is provided on the top of the confining pressure chamber.

9. The expansion ring test device based on carbon dioxide phase change according to claim 1, characterized in that: The acoustic impedance of the driving cylinder is the same as the acoustic impedance of the expansion ring sample.

10. The expansion ring test device based on carbon dioxide phase change according to claim 1, characterized in that: The carbon dioxide filling tube, the expansion ring sample and the driving cylinder are coaxially arranged.

11. The expansion ring test device based on carbon dioxide phase change according to claim 1, characterized in that: The outer side of the carbon dioxide filling tube is in close contact with the inner side of the driving cylinder.

12. The expansion ring test device based on carbon dioxide phase change according to claim 1, characterized in that: It also includes a monitoring component, which includes a full-digital dynamic servo sensor, a high-speed camera, a laser velocimeter, a plurality of strain gauges and a computer; the full-digital dynamic servo sensor is arranged in the confining pressure loading structure; the high-speed camera is arranged on the confining pressure loading structure, and is used to shoot the dynamic fragmentation process of the expansion ring sample; the laser velocimeter is arranged in the confining pressure loading structure and is aligned with the axial center position of the expansion ring sample, and is used to measure the radial expansion speed of the expansion ring sample; the plurality of strain gauges are arranged on the expansion ring sample at intervals, and are used to collect the strain signal of the expansion ring sample during the test; the computer is electrically connected to the strain gauge, the full-digital dynamic servo sensor, the high-speed camera and the laser velocimeter respectively.

13. A test method for an expansion ring test device based on carbon dioxide phase change according to any one of claims 1 to 12, characterized in that: The following steps are involved: S1, making the material to be studied into a standard expansion ring specimen according to the test requirements; arranging a plurality of strain gauges on the outer surface of the expansion ring specimen to measure the strain signal of the expansion ring specimen during the test; S2, placing the expansion ring sample in the confining pressure loading structure, placing the driving cylinder in the inner cavity of the expansion ring sample and closely attached to the inner circumferential wall of the expansion ring sample, placing the carbon dioxide filling tube in the inner cavity of the driving cylinder and closely attached to the inner circumferential wall of the driving cylinder; fixing a high-speed camera and a laser velocimeter on the confining pressure loading structure, and starting the computer to prepare for the test; S3, applying corresponding confining pressure to the expansion ring specimen through the water pump on the confining pressure loading structure and the high-frequency response water transmission pipeline according to the test requirements; S4, after the confining pressure loading is completed, the power supply is connected to the electric lead of the carbon dioxide filling tube to heat the liquid carbon dioxide in the carbon dioxide filling tube, and when the liquid carbon dioxide in the carbon dioxide filling tube absorbs heat, it instantly vaporizes and generates a shock wave to expand and break the expansion ring sample; S5, cut off the power supply after the test.

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