An expansion ring test device based on carbon dioxide phase change and its test method

Abstract

The present application provides an expansion ring test device based on carbon dioxide phase change and a test method thereof, which includes a support base, a confining pressure loading structure, a driving cylinder, a carbon dioxide filling pipe, and an expansion ring specimen; the driving cylinder is installed on the support base; the expansion ring specimen 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 pipe is hermetically arranged in the inner cavity of the driving cylinder, and a shock wave that causes the expansion ring specimen to expand and break is generated by heating the carbon dioxide filling pipe. The device and method avoid potential interference of a complex electromagnetic field environment on the experimental results, have a wide application range, simplify the experimental equipment and reduce energy consumption, and also significantly improve the safety and controllability of the experimental process, and reduce the harm of the shock wave and fragments generated by the explosion to the experimental equipment and the surrounding environment.

Description

Technical Field

[0001] This application relates to the field of impact crushing of materials, and particularly to an expansion ring test device based on carbon dioxide phase change and its test method. Background Art

[0002] The impact crushing of brittle materials, as the research focus of solid mechanics, has been widely applied in many key fields such as mining, blasting, geotechnical engineering, aerospace, and materials engineering. The expansion ring test has a simple structural form and sufficient theoretical basis, and is the main method for studying the impact crushing characteristics of brittle materials. Currently, the expansion ring tests under impact loading mainly include electromagnetic expansion rings, explosive expansion rings, hydraulic expansion rings, etc.; among them, the electromagnetic expansion ring uses the Lorentz force as the driving force and can precisely control the expansion strain rate. However, the prerequisite for this test method is that the expansion ring material needs to have good electrical conductivity, and 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 achievable expansion strain rate is relatively low, making it difficult to apply to materials with low conductivity such as rocks and ceramics.

[0003] The explosive expansion ring uses the shock wave generated by explosives as the driving force, can easily achieve high-strain-rate expansion, and has no special requirements for the electrical conductivity and other physical properties of the expansion ring material, increasing the applicability of the expansion ring test. At the same time, due to the rapid and concentrated release of energy during the explosion process, the temperature rise phenomenon is not obvious, reducing the interference of the thermal effect on the test results. However, the propagation characteristics of the shock wave may affect the one-dimensional stress state of the expansion ring test, resulting in the deviation of the test results from the theoretical model. In addition, the uncertainty of the explosion process increases the difficulty of precise control of the strain rate, affecting the repeatability and reliability of the test results. Moreover, explosion tests usually involve the approval, storage, transportation, use, and post-test safety treatment of explosives, increasing the cost and complexity of the test and making it difficult to be popularized to civilian research institutions.

[0004] The hydraulic expansion ring utilizes the physical property that liquids are approximately incompressible. By rapidly impacting the piston externally, the liquid in the piston cylinder can generate high-speed expansion in a short time, realizing the dynamic tensile fracture of the expansion ring. However, the achievable strain rate level is relatively low, and the flow and pressure transmission of the hydraulic pressure in the pipeline require a certain amount of time, resulting in a relatively slow loading response speed of the hydraulic system and being unable to meet the application requirements of the expansion ring at medium and high strain rates. Summary of the Invention

[0005] One of the purposes of this application is to provide an expanding ring test device based on carbon dioxide phase change and its test method. By using the impact pressure generated by the phase change of supercritical carbon dioxide as an alternative source to traditional electromagnetic, explosive, and hydraulic methods, dynamic expansion test research in the low, medium, and high wide strain rate ranges can be achieved. At the same time, this device applies a uniform and controllable static confining pressure around the expanding ring through a confining pressure loading structure to simulate the in-situ stress environment of materials such as deep rocks. Therefore, the test data obtained is more real and reliable.

[0006] The technical solution of this application is as follows:

[0007] An expanding ring test device based on carbon dioxide phase change, comprising a support base, a confining pressure loading structure, a driving cylinder, a carbon dioxide filling tube, and an expanding ring specimen. The driving cylinder is installed on the support base. The expanding ring specimen 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 a confining pressure around the driving cylinder. The carbon dioxide filling tube is hermetically arranged in the inner cavity of the driving cylinder, and by heating the carbon dioxide filling tube, a shock wave is generated to cause the expanding ring specimen to expand and break.

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

[0009] As a technical solution of this application, 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 provided on the top end.

[0010] As a technical solution of this application, the support base is made of a steel material with low elongation rate and high strength.

[0011] As a technical solution of this application, a lower sealing cover is hermetically installed on the bottom opening of the driving cylinder, and an upper sealing cover is hermetically installed 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 this application, the carbon dioxide filling tube includes a tube body, a heating tube, and an electrical 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 cavity of the tube body is filled with liquid carbon dioxide. One end of the electrical lead extends into the heating tube, and an electrical primer is arranged at 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 arranged at the lower part of one side; the water pump is connected with a high-frequency response waterway transmission pipeline, and the water outlet of the high-frequency response waterway transmission pipeline is connected to the inner cavity of the confining pressure loading structure; an observation window is arranged at 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 upper cover 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 that of the expansion ring specimen.

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

[0017] As a technical solution of the present application, the outer side of the carbon dioxide filling pipe is closely attached to the inner side of the driving cylinder.

[0018] As a technical solution of the present application, it further includes a monitoring component, and the monitoring component 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 for shooting the dynamic fragmentation process of the expansion ring specimen; the laser velocimeter is arranged in the confining pressure loading structure and aligned with the central position of the axial direction of the expansion ring specimen for measuring the radial expansion speed of the expansion ring specimen; a plurality of the strain gauges are respectively arranged on the expansion ring specimen at intervals for collecting the strain signals of the expansion ring specimen during the test process; the computer is electrically connected to the strain gauges, the full-digital dynamic servo sensor, the high-speed camera and the laser velocimeter respectively.

[0019] A test method for an expansion ring test device based on carbon dioxide phase change as described above includes 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 signals of the expansion ring specimen during the test process;

[0021] S2. Place the expanded ring specimen in the confining pressure loading structure, place the driving cylinder in the inner cavity of the expanded ring specimen and closely adhere to the inner peripheral wall of the expanded ring specimen, and place the carbon dioxide filling tube in the inner cavity of the driving cylinder and closely adhere to the inner peripheral wall of the driving cylinder; fix a high-speed camera and a laser velocimeter on the confining pressure loading structure, and start the computer to prepare for the test;

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

[0023] S4. After the confining pressure is loaded, connect the power supply and the electrical lead of the carbon dioxide filling tube, heat the liquid carbon dioxide in the carbon dioxide filling tube. When the liquid carbon dioxide in the carbon dioxide filling tube absorbs heat and instantaneously vaporizes to generate a shock wave, the expanded ring specimen is expanded and broken;

[0024] S5. Cut off the power supply after the test.

[0025] Advantages of the present application:

[0026] In the expanded ring test device and its test method based on carbon dioxide phase change of the present application, compared with electromagnetic drive, this device and method avoid potential interference of the complex electromagnetic field environment on the test results by controlling the heating rate and filling amount of carbon dioxide, expand the scope of applicable test materials, simplify the test equipment and reduce energy consumption; compared with explosion drive, this device and method significantly improve the safety and controllability of the test process by controlling the heating rate and filling amount of carbon dioxide, and reduce the harm of the shock wave and fragments generated by the explosion to the test equipment and the surrounding environment; compared with hydraulic drive, it achieves the effects of higher response speed and pressure regulation accuracy by controlling the amount of carbon dioxide heating agent and the amount of liquid carbon dioxide, can more accurately simulate the crushing behavior of the expanded ring specimen under dynamic loading conditions, and realize expansion tests at different pressures by controlling the heating rate and filling amount of carbon dioxide. In addition, this device applies a uniform and controllable static confining pressure around the expanded ring specimen through the confining pressure loading structure, which is an initial static loading method, to simulate the in-situ stress environment of materials such as deep rocks, making the test results more real and reliable. Moreover, it uses the expansion force caused by carbon dioxide phase change technology to conduct a dynamic expansion test on the expanded ring specimen, which can more realistically simulate the dynamic tensile failure of materials in the deep environment, and thus makes the test results more real and reliable. Description of the drawings

[0027] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0028] Figure 1 Schematic diagram of the expansion ring test device and its test method based on carbon dioxide phase change provided by the embodiments of the present application;

[0029] Figure 2 Schematic diagram of the expansion ring specimen provided by the embodiments of the present application;

[0030] Figure 3 Schematic diagram of the driving cylinder provided by the embodiments of the present application;

[0031] Figure 4 Schematic diagram of the carbon dioxide filling tube provided by the embodiments of the present application;

[0032] Figure 5 Schematic diagram of the confining pressure loading structure provided by the embodiments of the present application.

[0033] Icon: 1 - support base; 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 - electrical lead; 12 - carbon dioxide heating agent; 13 - liquid carbon dioxide; 14 - electrical 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 implementation manners

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, 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 drawings is not intended to limit the scope of the present application to be protected, but only represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0036] It should be noted that like reference numerals and letters refer to like items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying 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 construed as a limitation to 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 additional features therebetween. Moreover, the first feature being above, over, and on the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being below, under, and beneath the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0039] In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging, but may be slightly inclined. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but may be slightly inclined.

[0040] In the description of the present application, it should also be noted that, unless otherwise clearly specified and limited, the terms "arranged", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0041] Embodiment:

[0042] Please refer to Figure 1 and, in conjunction with reference to Figures 2 to 5, this application provides an expansion ring test device based on carbon dioxide phase change, which mainly includes a support base 1, a confining pressure loading structure, a driving cylinder 2, a carbon dioxide filling pipe 3, an expansion ring specimen 4, and a monitoring component. Among them, the driving cylinder 2 is installed on the support base 1. At the same time, the expansion ring specimen 4 is sleeved on the driving cylinder 2 and is located 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 around the driving cylinder 2. And, the carbon dioxide filling pipe 3 is hermetically arranged in the inner cavity of the driving cylinder 2. The outer side of the carbon dioxide filling pipe 3 is closely attached to the inner side of the driving cylinder 2, and it is ensured that the carbon dioxide filling pipe 3, the expansion ring specimen 4, and the driving cylinder 2 are coaxially arranged to reduce the test error caused by introducing non-axial force or torque. By heating the carbon dioxide filling pipe 3, a shock wave that causes the expansion ring specimen 4 to expand and break is generated. And, the expansion ring specimen 4 can freely select different types and properties of materials according to research needs, broadening the material range of experimental research. In addition, the monitoring component is used to monitor the test process of the expansion ring specimen 4.

[0043] Furthermore, a positioning groove with an upward opening and threads on the inner wall is provided on the support base 1, and the lower end of the driving cylinder 2 is threadedly connected to the positioning groove. A lower end cover 5 is arranged 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 end.

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

[0045] Furthermore, a lower sealing cover 7 is hermetically installed on the bottom opening of the driving cylinder 2, and an upper sealing cover 8 is hermetically installed on the top opening. The carbon dioxide filling pipe 3 is arranged between the upper sealing cover 8 and the lower sealing cover 7. And, the carbon dioxide filling pipe 3 includes a pipe body 9, a heating pipe 10, and an electrical lead 11. The heating pipe 10 is detachably arranged in the inner cavity of the pipe body 9, and the heating pipe 10 is filled with a carbon dioxide heating agent 12. The cavity of the pipe body 9 is filled with liquid carbon dioxide 13. One end of the electrical lead 11 extends into the heating pipe 10, and an electrical ignition head 14 is arranged at the end. During the test, the electrical lead 11 is connected to the power supply. The electrical 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 pipe 10. After the liquid carbon dioxide 13 absorbs a certain amount of heat, it instantaneously vaporizes, generating an impact force to achieve the expansion and breakage of the expansion ring specimen 4. Cut off the power supply in time after the test.

[0046] By controlling the dosage of the carbon dioxide heating agent 12, the phase transition temperature of supercritical carbon dioxide can be controlled to achieve different air pressure loading, and further achieve different expansion rate loading. By controlling the heating rate and filling amount of carbon dioxide, different air pressures and different pressure rising rates can be achieved, and further different expansion rates can be obtained. Moreover, the potential interference of the complex electromagnetic field environment on the experimental results is avoided, the range of applicable test materials is expanded, the experimental equipment is simplified, and the energy consumption is reduced; by controlling the heating rate and filling amount of carbon dioxide, the safety and controllability of the experimental process are significantly improved, and the harm of the shock wave and fragments generated by the explosion to the experimental equipment and the surrounding environment is reduced; it achieves 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 fragmentation behavior of the expanding ring specimen 4 under dynamic loading conditions, and achieve expansion tests at different pressures by controlling the heating rate and filling amount of carbon dioxide. Therefore, by using the expansion force caused by the carbon dioxide phase change technology to conduct a dynamic expansion test on the expanding ring specimen 4, it can more realistically simulate the dynamic tensile failure of materials in the deep environment, and thus make the test results more real and reliable.

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

[0048] It should be noted that the driving cylinder 2 is made of high-strength and corrosion-resistant stainless steel or alloy steel, so as to keep it intact as much as possible during the test. The outer diameter of the driving cylinder 2 is 49 - 52 mm, the inner diameter is 46 - 49 mm, and the height is 10 cm. In addition, the acoustic impedance of the driving cylinder 2 is the same as that of the expansion ring specimen 4. The acoustic impedance characteristics of the material of the driving cylinder 2 are adjusted by methods such as heat treatment, surface treatment or chemical treatment, so that its acoustic impedance is closer to that of the expansion ring specimen 4; the contact interface between the driving cylinder 2 and the expansion ring specimen 4 is optimized to ensure close fit between the two, reducing the influence of air gaps or impurities on sound wave transmission; it is ensured that the driving cylinder 2 and the expansion ring specimen 4 are precisely matched in thickness dimensions, so as to reduce sound wave scattering and energy loss caused by size differences, reduce the reflection and energy loss of shock waves at the interface between the driving cylinder 2 and the expansion ring specimen 4, and enable the driving energy to be efficiently transmitted to the expansion ring specimen 4, thereby initiating and maintaining the one-dimensional stress state of the expansion ring specimen 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 closely attached to the inner side of the expansion ring specimen 4. The lower sealing cover 7 and the upper sealing cover 8 are respectively installed at the upper and lower ends of the carbon dioxide filling pipe 3, and the upper end cover 6 and the lower end cover 5 are respectively installed at 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. A cover plate 20 is provided on the upper part of 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. The water pump 16 is connected with a high-frequency response waterway transmission pipeline 17, and the water outlet of the high-frequency response waterway 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 fragmentation of the expansion ring specimen 4. When conducting the test, the cover plate 20 of the confining pressure chamber 15 is opened to facilitate the placement of the expansion ring specimen 4, the driving cylinder 2 and the carbon dioxide filling pipe 3; the inner diameter of the confining pressure chamber 15 is larger than the outer diameter of the expansion ring specimen 4 to provide a space for the expansion and fragmentation of the expansion ring specimen 4. The confining pressure chamber 15 applies a uniform stress to the expansion ring specimen 4 through the water pump 16 and the high-frequency response waterway transmission pipeline 17, up to 20 MPa at most. A sealing ring is provided at the connection between the confining pressure chamber 15 and the water pump 16. Start the water pump 16 and gradually increase the pressure until the pressure in the confining pressure chamber 15 reaches the preset value.

[0051] Therefore, through this initial static loading method of the confining pressure loading structure, a uniform and controllable static confining pressure is applied around the expansion ring specimen 4 to simulate the in-situ stress environment of materials such as deep rocks, making the test results more real and reliable.

[0052] It should be noted that the outer diameter of the expansion ring specimen 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 specimen 4 has no end effect, and when the thickness of the expansion ring specimen 4 is relatively thin, it maintains an almost 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. Among them, the full-digital dynamic servo sensor is arranged inside the confining pressure loading structure to complete the loading of the required confining pressure for the test and dynamically adjust the change in confining pressure caused by the deformation of the expansion ring specimen 4 during the experiment. At the same time, the high-speed camera is set on the confining pressure chamber 15 and above the observation window 18 to photograph the dynamic fragmentation process of the expansion ring specimen 4. In addition, the laser velocimeter is arranged inside the confining pressure loading structure and aligned with the central position of the axial direction of the expansion ring specimen 4 to measure the radial expansion speed of the expansion ring specimen 4. And a plurality of strain gauges 19 are respectively arranged on the expansion ring specimen 4 at intervals to collect the strain signals of the expansion ring specimen 4 during the test. The strain gauges 19 can capture and record the minute deformations that occur during the expansion process of the expansion ring specimen 4 in real time and accurately, and further analyze the mechanical properties of the expansion ring specimen 4. The computer is electrically connected to the strain gauges 19, the full-digital dynamic servo sensor, the high-speed camera, and the laser velocimeter respectively.

[0054] It should be noted that the phase change of supercritical carbon dioxide is a process that can be precisely regulated 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, and various pressure levels from mild impact to strong impact can be obtained, so as to meet the test requirements at different 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, the energy is quickly released and can reach the required strain rate 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, improving 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, etc., the phase change conditions can be adjusted by this device to generate appropriate impact pressure for the test.

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

[0056] S1. Fabricate the standard expansion ring specimen 4 from the material to be studied according to the test requirements; arrange a plurality of strain gauges 19 on the outer surface of the expansion ring specimen 4 to measure the strain signal of the expansion ring specimen 4 during the test;

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

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

[0059] S4. After the confining pressure is loaded, connect the power supply and the electrical lead 11 of the carbon dioxide filling tube 3, heat the liquid carbon dioxide 13 in the carbon dioxide filling tube 3. When the liquid carbon dioxide 13 in the carbon dioxide filling tube 3 absorbs heat and instantly vaporizes to generate a shock wave, so as to expand and break the expansion ring specimen 4;

[0060] S5. Cut off the power supply after the test.

[0061] In summary, in the expansion ring test device and its test method based on carbon dioxide phase change of the present application, compared with electromagnetic drive, this device and method avoid potential interference of the complex electromagnetic field environment on the test results by adjusting the filling amount and heating rate of the liquid carbon dioxide 13, expand the range of applicable test materials, simplify the test equipment and reduce energy consumption; compared with explosion drive, this device and method significantly improve the safety and controllability of the test process by controlling the heating rate and filling amount of carbon dioxide, and reduce the harm of the shock wave and fragments generated by the explosion to the test equipment and the surrounding environment; compared with hydraulic drive, it realizes 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 the liquid carbon dioxide 13, can more accurately simulate the crushing behavior of the expansion ring specimen 4 under dynamic loading conditions, and realizes expansion tests at different pressures by controlling the heating rate and filling amount of carbon dioxide. In addition, this device applies a uniform and controllable static confining pressure around the expansion ring specimen 4 through the confining pressure loading structure, an initial static loading method, to simulate the in-situ stress environment of materials such as deep rocks, making the test results more real and reliable. Moreover, it conducts a dynamic expansion test on the expansion ring specimen 4 by using the expansion force caused by the carbon dioxide phase change technology, which can more realistically simulate the dynamic tensile failure of materials in the deep environment, and thus makes the test results more real and reliable.

[0062] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various modifications and changes can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within 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 base, a confining pressure loading structure, a drive cylinder, a carbon dioxide filling pipe, and an expansion ring specimen; the drive cylinder is installed on the support base; the expansion ring specimen is sleeved on the drive cylinder and is located in the inner cavity of the confining pressure loading structure; the confining pressure loading structure is sleeved on the drive cylinder and is used to apply confining pressure around the drive cylinder; the carbon dioxide filling pipe is hermetically arranged in the inner cavity of the drive cylinder, and a shock wave that causes the expansion ring specimen to expand and break is generated by heating the carbon dioxide filling pipe; the carbon dioxide filling pipe includes a pipe body, a heating pipe, and an electrical lead; the heating pipe is detachably arranged in the inner cavity of the pipe body, and the heating pipe is filled with a carbon dioxide heating agent; the pipe body cavity is filled with liquid carbon dioxide; one end of the electrical lead extends into the heating pipe, and an electrical igniter is arranged at the end. The confining pressure loading structure includes a confining pressure chamber; the confining pressure chamber is sleeved on the drive cylinder, and a water pump is arranged at the lower part of one side; the water pump is connected with a high-frequency response waterway transmission pipeline, and the water outlet of the high-frequency response waterway transmission pipeline is connected to the inner cavity of the confining pressure loading structure; an observation window is arranged at the middle part of one side of the confining pressure chamber.

2. The expansion ring test device based on carbon dioxide phase change according to claim 1, characterized in that, A positioning groove with an upward opening is formed on the support base, and the lower end of the drive cylinder is threadedly connected to the positioning groove.

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

4. The expansion ring test device based on carbon dioxide phase change according to claim 1, characterized in that, The support base is made of a steel material with low elongation rate and high strength.

5. The expansion ring test device based on carbon dioxide phase change according to claim 1, characterized in that, A lower sealing cover is hermetically installed on the bottom opening of the drive cylinder, and an upper sealing cover is hermetically installed 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 and test method based on carbon dioxide phase change according to claim 1, characterized in that, The confining pressure chamber is a pressure vessel made of high-strength alloy steel, and a cover plate is arranged on the confining pressure chamber.

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

8. The expansion ring test device based on carbon dioxide phase change according to claim 1, characterized in that, The carbon dioxide filling pipe, the expansion ring specimen, and the drive cylinder are coaxially arranged.

9. The expansion ring test device based on carbon dioxide phase change according to claim 1, wherein The outer side of the carbon dioxide filling pipe is closely attached to the inner side of the drive cylinder.

10. The expansion ring test device based on carbon dioxide phase change according to claim 1, characterized in that, It further includes a monitoring component, and the monitoring component 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 photograph 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 central position of the axial direction of the expansion ring specimen and is used to measure the radial expansion speed of the expansion ring specimen; a plurality of the strain gauges are respectively arranged on the expansion ring specimen at intervals and are used to collect the strain signals of the expansion ring specimen during the test process; the computer is electrically connected to the strain gauges, the full-digital dynamic servo sensor, the high-speed camera, and the laser velocimeter respectively.

11. A test method for an expansion ring test device based on carbon dioxide phase change as described in any one of claims 1 to 10, characterized in that, It includes the following steps: S1. Fabricate the material to be studied into standard expansion ring specimens according to the test requirements; arrange a plurality of strain gauges on the outer surface of the expansion ring specimens to measure the strain signals of the expansion ring specimens during the test; S2. Place the expansion ring specimens in the confining pressure loading structure, place the driving cylinder in the inner cavity of the expansion ring specimens and close to the inner peripheral wall of the expansion ring specimens, and place the carbon dioxide filling pipe in the inner cavity of the driving cylinder and close to the inner peripheral wall of the driving cylinder; fix a high-speed camera and a laser velocimeter on the confining pressure loading structure, and start the computer to prepare for the test; S3. Apply the corresponding confining pressure to the expansion ring specimens through the water pump and the high-frequency response water transmission pipeline on the confining pressure loading structure according to the test requirements; S4. After the confining pressure is loaded, connect the power supply and the electrical lead of the carbon dioxide filling pipe, heat the liquid carbon dioxide in the carbon dioxide filling pipe, and when the liquid carbon dioxide in the carbon dioxide filling pipe absorbs heat and instantaneously vaporizes to generate a shock wave to expand and break the expansion ring specimens; S5. Cut off the power supply after the test ends.

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