A vacuum confining pressure testing device and method

Abstract

This invention belongs to the technical field of deep space exploration geological engineering property testing and in-situ testing auxiliary equipment for large scientific facilities. It relates to a vacuum confining pressure testing device and method. The main structure includes an integrated confining pressure outer cylinder. The inner part of the outer cylinder is equipped with a latex sleeve that wraps the sample. The sample end is equipped with a sample end cap with an inverted conical groove. A floating self-locking pressure ring is fitted on the outside of the latex sleeve. A sliding embedded chamber rail is provided on the inner side of the end. The lower end of the outer cylinder is fixed to the base assembly, and the upper end is connected to the quick-release assembly. The quick-release assembly is equipped with a top cover with a male plug structure, which is adapted to the top opening of the piston pressure chamber for insertion and removal. An anti-extrusion retaining ring and a fluororubber O-ring are installed in the groove below the plug structure. When applying axial load for mechanical testing, the sliding displacement generated by the axially loaded piston pushes the self-locking pressure ring to tightly press and solidify the sample latex sleeve. At the same time, the embedded chamber rail absorbs the large displacement compression deformation of the sample.

Description

Technical Field

[0001] This invention belongs to the technical field of geological engineering property testing for deep space exploration and in-situ experimental auxiliary equipment for large scientific facilities. Specifically, it relates to a vacuum confining pressure testing device and method, which is adapted to vacuum multi-field coupled particle samples scanned by X-rays and neutrons. Background Technology

[0002] Lunar soil is the particulate medium that will be in direct contact with the moon during future landing, exploration, sample return, and in-situ construction. Its particle size distribution, particle morphology, pore structure, and interparticle contact state will collectively affect engineering behaviors such as load-bearing capacity, subsidence, core disturbance, and mechanical traction. Due to the scarcity of real lunar soil samples and the difficulty in supporting systematic mechanical loading experiments, using lunar soil simulants to conduct research on shallow geotechnical properties and in-situ structural responses has become an important foundation for subsequent research on landing safety, core stability, and parametric studies of lunar construction.

[0003] Based on a clear understanding of the sample type and water content, establishing the in-situ structural response of lunar regolith simulants during compressive deformation and shear instability is crucial. To directly observe the local compaction, shear band formation, and multiphysics dynamic evolution of real complex particles during loading, in-situ triaxial mechanical testing techniques combined with laboratory microfocus CT or synchrotron X-ray phase-contrast imaging (PCI) have been widely applied in recent years. However, existing in-situ triaxial mechanical testing devices and methods have the following significant limitations when applied to loose granular media such as lunar regolith simulants and extreme environment simulations:

[0004] First, in-situ triaxial testing often employs a "stepped stop-and-scan" strategy, where loading is interrupted after the axial strain reaches a specified point, and the piston remains in a fixed position for a sufficiently long time to complete the X-ray scan. Due to the rheological and creep properties of granular materials and rock media, intermittent stop-and-scan loading can induce significant stress relaxation (e.g., stress drop during scanning), severely interfering with and altering the material's true mechanical response, yield trajectory, and failure characteristics. When applied to loose granular media such as lunar soil simulants, there are problems such as stress relaxation caused by stop-and-scan loading leading to distortion of the true mechanical response and the inability to perform 360° continuous rotational loading due to pipeline entanglement.

[0005] Secondly, traditional high-pressure test chambers typically employ a circumferential array of high-strength bolts and heavy-duty flanges for fastening to resist the enormous axial separation force generated by the internal high-pressure fluid. This results in an extremely cumbersome and time-consuming disassembly and assembly process, severely wasting the extremely expensive testing time of synchrotron radiation beamlines. Furthermore, the tedious and repeated disassembly and assembly can easily cause microscopic positional shifts of the sample in the scanning optical path, reducing initial alignment accuracy and severely limiting the efficiency of in-situ experiments. In practice, not only is it necessary to use a special torque wrench to perform complex diagonal tightening of the bolts, but this process must also be repeated every time a sample is replaced. In large synchrotron radiation beamlines, high-energy beam time is extremely expensive and short; the heavy-duty flange fastening method can easily consume tens of minutes or even hours of disassembly and assembly time, resulting in significant resource waste. In addition, the cumbersome disassembly and assembly process involves a large amount of pipeline interference, which can easily cause microscopic positional shifts of the sample in the scanning optical path, leading to a decrease in the initial alignment accuracy of in-situ scanning.

[0006] Third, traditional rigid clamps or static O-ring seals are difficult to effectively reduce the diameter of powdery (such as lunar soil simulants) or small-sized samples. Under extreme axial loading and high confining pressure, large axial settlement or volume compaction of granular samples can pull on the sealing area at the end of the rubber sleeve. Simultaneously, the heavy metal clamps can cause severe artifact interference to X-ray or neutron beams, obstructing the core observation field. Under extreme loads, the reliability of traditional rubber sleeve sealing structures is extremely poor, easily leading to test environment failure. In triaxial mechanical testing, the sample is usually encased in a flexible latex sleeve or heat-shrink sleeve to isolate the confining fluid from the internal pore fluid. Even more critically, when axial loading causes large deformation, displacement, compression of the particle sample or when extremely high confining pressure is applied, the latex sleeve at the static seal is easily pulled at the end, leading to wrinkles, slippage, or even being cut by the rigid clamp. The lack of an internal adaptive dynamic compensation mechanism means that once the contact surface is subjected to uneven force, the high-pressure confining medium will instantly puncture or leak into the sample, directly causing the internal vacuum environment to be destroyed, the sample to be contaminated, and the experiment to fail.

[0007] For example, Chinese Patent 202610443583.8 discloses a multi-field coupling testing system for loose coal and rock mass based on in-situ computed tomography (CT), comprising: an in-situ reaction device, a CT device, a gas supply device, a gas analysis device, and a data acquisition module; wherein, the in-situ reaction device is used to fill the loose coal and rock mass, and the quartz outer wall of the in-situ reaction device is provided with a vacuum-insulated chamber; the in-situ reaction device is rotatably installed inside the CT device, and the CT device is used for tomographic scanning of the loose coal and rock mass and obtaining structural images of the loose coal and rock mass; the gas supply device's outlet end is connected to the inlet end of the in-situ reaction device, and the gas supply device is used to supply gas to the loose coal and rock mass. The in-situ reaction device introduces oxidizing gas at a preset temperature and gradually heats the loose coal and rock mass to the target temperature; the gas analysis device is connected to the gas outlet of the in-situ reaction device and is used to detect the concentration of gaseous products in the loose coal and rock mass; the data acquisition module is used to obtain rotational dynamic structural images of the loose coal and rock mass at different temperature stages through a CT device, and to reconstruct the structural images to obtain the three-dimensional microstructure of the loose coal and rock mass at different temperature stages; and, based on the temperature, gaseous product concentration, and three-dimensional microstructure of the loose coal and rock mass, a multi-field coupled evolution model of the loose coal and rock mass is constructed. Chinese Patent 202511323386.4 discloses a multi-field coupling testing system for rocks, comprising: a multi-physics field coupling loading system, including: a mechanical loading system, comprising a loading mechanism, wherein the loading mechanism is provided with a cavity, and the cavity is sealed and accommodated with a rock sample wrapped with a heat-shrink film, the loading mechanism being used to apply axial pressure and confining pressure to the rock sample; a seepage loading system, for applying osmotic pressure to the rock sample; a temperature loading system, for applying a temperature field to the rock sample; a multi-field data monitoring system, including: a mechanical monitoring system, comprising a controller in the loading mechanism; an acoustic monitoring system, comprising a longitudinal wave detector and a transverse wave detector disposed on the rock sample; a deformation monitoring system, comprising a DAS system, the DAS system comprising distributed fiber optic acoustic sensors spirally wound at equal intervals on the rock sample, the distributed fiber optic acoustic sensors being electrically connected to a distributed fiber optic demodulator; a CT scanning system, for performing CT scans on the rock sample; and a multi-field data acquisition system, comprising a host computer electrically connected to the multi-field data monitoring system, the seepage loading system, and the temperature loading system.Chinese Patent 202311628098.0 discloses an adaptive multi-field coupling testing device for dynamic and static loads on coal and rock, including an axial loading device, a confining pressure loading system, a biaxial shearing system, and a pore adjustment system. The axial loading device includes an axial loading frame, with a loading cylinder mounted on the upper crossbeam and a support cylinder mounted on the lower base. A pressure chamber body is located in the middle of the axial loading frame, comprising a pressure chamber base, a pressure chamber cylinder, a self-balancing piston, a sealing ring, a pressure chamber trolley, a hand valve, and upper and lower pressure blocks for the sample. A pressure chamber support device is installed below the inner wall of the axial loading frame, with a pressure chamber trolley located in the middle of the upper surface of the support device. Guide rails are installed on both sides of the upper surface of the support device corresponding to the sides of the pressure chamber trolley. The pressure chamber cylinder is mounted on the upper surface of the pressure chamber trolley via the pressure chamber base. A sealing ring is installed between the chamber cylinder and the pressure chamber base. An axial pressure sensor is installed on the upper end of the pressure chamber body. An axial loading device is installed on the upper surface inside the axial loading frame at the position corresponding to the axial pressure sensor. A loading cylinder displacement sensor is installed on the upper surface inside the axial loading frame at the position corresponding to the axial loading device. A support platform is provided on one side of the outer wall of the pressure chamber support device. A shear loading frame is installed on one side of the upper surface of the support platform. A shear loading device is installed on the outer wall of the shear loading frame near the axial loading frame. A shear cylinder displacement sensor is installed on the outer wall of the shear loading device near the axial loading frame. A shear pressure sensor is installed inside the shear loading frame at the position corresponding to the shear loading device. An upper shear box is provided inside the shear loading frame near the shear pressure sensor. A lower shear box is provided inside the shear loading frame away from the shear pressure sensor.

[0008] In summary, existing multi-field coupled in-situ testing equipment cannot effectively integrate extreme vacuum, cryogenic and high-temperature environments, and high-pressure loading within a confined space. Furthermore, it lacks a synchronous data acquisition mechanism that aligns with the timestamps of synchrotron radiation beamline detectors and shutter signals. This results in significant technical bottlenecks in modular quick-assembly and disassembly capabilities and microscale dynamic sealing reliability during synchrotron radiation or micro-beam X-ray CT scanning experiments. Therefore, there is an urgent need to develop and design a novel in-situ vacuum confining pressure testing device and method. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing technologies and to develop and design a vacuum confining pressure testing device and method that is adaptable to extreme environments, compatible with high-energy beam scanning, and has both efficient assembly and high airtightness adaptive sealing capabilities.

[0010] To achieve the above objectives, the present invention relates to a vacuum confining pressure testing device, the main structure of which includes a base assembly, an integrated confining pressure outer cylinder, a quick-release assembly, an axial loading piston, and an adaptive rubber sleeve sealing assembly.

[0011] The adaptive rubber sleeve sealing assembly is located inside the integrated confining pressure outer cylinder and is used to wrap the sample;

[0012] The axially loaded piston passes axially through the quick-release assembly, and its bottom end abuts against the adaptive rubber sleeve sealing assembly;

[0013] The lower end of the integrated confining pressure outer cylinder is fixed to the base assembly, the upper end is connected to the quick-release assembly, and forms the upper wall of the low-attenuation cylinder at least in the corresponding sample scanning area.

[0014] The upper end of the base assembly is sealed to the outer cylinder of the integrated confining pressure chamber, and forms a low-attenuation cylinder at least in the scanning area of ​​the corresponding sample.

[0015] The base assembly includes a lower anvil and a locking flange ring;

[0016] The quick-release assembly includes a piston pressure chamber and a top cover, eliminating the traditional flange bolt fastening structure. The top cover is inserted into the piston pressure chamber through a plug-in fit. The piston pressure chamber is fixed to the top of the integrated outer cylinder of the pressure chamber. The top cover has a male plug structure, and its outer contour is adapted to the top opening of the piston pressure chamber to achieve quick disassembly and closure. There is a groove below the plug structure of the top cover, in which a top cover anti-extrusion retaining ring and a fluororubber O-ring are installed. Even when the inside is filled with high-pressure medium, it can achieve a static seal against extrusion of high-pressure fluid without heavy fasteners.

[0017] The adaptive rubber sleeve sealing assembly includes a sample latex sleeve, a sample end cap with an inverted conical groove, a floating self-locking pressure ring, and a sliding embedded compartment rail set on the inner side of the end of the sample latex sleeve. The sample end caps are respectively set at both ends of the sample, and the outer cylindrical surface is machined with an inverted conical groove structure. The sample latex sleeve wraps around the sample and the sample end cap. The self-locking pressure ring is sleeved on the outside of the sample latex sleeve, and its initial position corresponds to the sample end cap. The embedded compartment rail is a ring or cylindrical support component. Its outer circumference fits against the inner wall of the end of the sample latex sleeve, and its inner circumference is sleeved on the outer circumferential guide surface of the sample end cap, and it slides axially with the sample end cap, having a sliding stroke along the axial direction.

[0018] In addition, a carbon fiber pad is horizontally placed between the sample and the sample end cap.

[0019] The materials used for the outer casing of the integrated confining pressure chamber include polyetheretherketone (PEEK) and titanium alloy.

[0020] The present invention relates to a vacuum confining pressure testing device. When an axial load is applied, the axial loading piston slides downward, abutting and pushing the self-locking pressure ring. This forces the self-locking pressure ring to generate a radial contraction locking force along the inverted conical groove, simultaneously pressurizing the sample and mechanically compressing the adaptive rubber sleeve sealing assembly. This locks and pushes the self-locking pressure ring to lock the end of the sample's latex sleeve. At the same time, the embedded chamber rail compensates for the axial settlement displacement during the sample compression process. Without using external rigid clamps, a passive adaptive high airtightness seal is achieved for small / powdered samples, and a continuous sealing fit is maintained between the end of the sample's latex sleeve and the sample end cap.

[0021] This invention relates to a vacuum confining pressure testing device. In use, it serves as a clamping device connected to atmosphere and fluid control pipelines. Combined with a flexible heating / cooling module, a chiller, a multi-parameter data acquisition module, and a synchrotron radiation beamline detector, it forms a synchrotron radiation-based extreme environment multi-field coupling in-situ testing system. This system enables in-situ scanning and testing of samples under extreme environments, supporting dynamic in-situ measurements on a synchrotron radiation CT scanning platform that simultaneously rotates, applies constant strain rate loading, and performs online CT scanning. This completely eliminates and reduces stress relaxation errors caused by traditional "stop-scanning." Through parallel fine-tuning of the slow-pumping air path and a multi-mode interchangeable chamber design, it accommodates high vacuum mode, micro-positive pressure loading, negative pressure environment construction, and displacement compensation of the embedded chamber rails. This ensures that loose particle samples are prevented from fluidization, temperature and water are controlled, and deep-earth rock samples are tested at 100°C. To meet the multi-functional expansion requirements of conventional MPa high confining pressure testing, the end of the rubber sleeve can still maintain stable sealing during large deformation compression. Through the DAQ-TTL collaborative triggering architecture, the force, deformation, local temperature field and high vacuum data are aligned with the frame-by-frame absolute time timestamp of the synchrotron radiation exposure shutter, which significantly improves the accuracy of in-situ dynamic characterization of the entire process of yielding and shear instability of loose granular materials.

[0022] The atmosphere and fluid control pipeline includes a high-purity inert gas cylinder, a high-vacuum isolation valve, and a fine-tuning needle valve. The high-purity inert gas cylinder is connected to the clamping device in sequence through the high-vacuum isolation valve and the fine-tuning needle valve.

[0023] A flexible heating / cooling module is enclosed on the outside of the clamping device;

[0024] The chiller is connected to the flexible heating / cooling module to provide it with circulating cooling medium;

[0025] The multi-parameter data acquisition module is electrically connected to various sensors installed on the clamping device and the atmosphere and fluid control lines;

[0026] The specific process for testing the displacement, steady-state, and transient permeability of low-permeability rock samples includes the following steps:

[0027] S1. Sample packaging and device assembly

[0028] First, place the sample inside the sample latex sleeve, assemble the sample end caps and pads at its upper and lower ends, and fit the embedded compartment rail and self-locking pressure ring on the outside of the sample latex sleeve.

[0029] Then, the assembled sample is installed on the lower anvil, and the outer cylinder and piston pressure chamber are inserted in sequence.

[0030] Finally, the top cover is inserted into the improved piston pressure chamber to complete the quick-release locking, and the axially loaded piston is driven to press the self-locking pressure ring downward to perform mechanical self-locking of the sealing assembly;

[0031] S2, Vacuuming and Atmosphere Reconstruction

[0032] First, close the exhaust valve and high vacuum isolation valve on the clamping device that are connected to the outside world;

[0033] Then, open the fine-tuning needle valve and adjust it to the slow-pulse setting;

[0034] Finally, turn on the external vacuum pump and slowly evacuate the inside of the clamping device through the fine-tuning needle valve to prevent the sample from splashing. Once the set standard is reached, turn off the vacuum pump, open the high vacuum isolation valve, adjust the fine-tuning needle valve, establish negative pressure, and slowly fill in inert gas to create the protective atmosphere required for the experiment.

[0035] S3. Apply confining pressure and control temperature.

[0036] Open the exhaust valve and the external confining pressure pump to pump fluid medium into the clamping device. Once fluid flows out of the exhaust valve, close the exhaust valve and continue to use the external confining pressure pump to apply confining pressure to the clamping device until the set conditions are met.

[0037] Start the chiller and flexible heating / cooling module to heat or cool the clamping device until the sample temperature reaches the preset lunar extreme thermal environment conditions.

[0038] S4, In-situ Axial Compression Displacement and Synchronous Scanning

[0039] An axial load is applied to the sample by an axial loading piston to perform axial compression load. During the compression process, the embedded chamber rail slides with the axial settlement of the sample to maintain the end seal of the sample latex sleeve. When the axial loading piston moves downward, it pushes the self-locking pressure ring, causing the self-locking pressure ring to generate radial contraction locking force along the inverted conical groove of the sample end cap. The embedded chamber rail slides axially along the outer peripheral guide surface of the sample end cap to reduce the pull of the sample compression settlement on the end seal area of ​​the sample latex sleeve.

[0040] Simultaneously, the multi-parameter data acquisition module is activated to collect data on loading force, lateral pressure mechanics, temperature, pipeline, and vacuum in real time. At the set deformation node, the shutter signal emitted by the synchrotron radiation beamline detector is received. The mechanical and thermal data are precisely aligned with the timestamp of the X-ray tomographic imaging obtained synchronously through the multi-parameter data acquisition module to obtain the three-dimensional evolution image of the sample in situ.

[0041] S5. Pressure relief and sample recovery

[0042] First, reduce the axial load to zero, turn off the chiller and flexible heating / cooling module, and allow the clamping device to return to room temperature;

[0043] Then, reduce the pressure of the external confining pressure pump to zero and open the corresponding pipeline to discharge the fluid medium;

[0044] Finally, the top cover was removed, the piston pressure chamber and outer cylinder were taken out, and the sample was removed for data analysis.

[0045] Compared with the prior art, this invention features an inner latex sleeve that encloses the sample within the outer cylinder. The sample end has a sample cap with an inverted conical groove. A floating self-locking pressure ring is fitted outside the latex sleeve, and a sliding embedded chamber rail is provided on the inner side of the end. The lower end of the outer cylinder is fixed to the base assembly, and the upper end is connected to a quick-release assembly. The quick-release assembly has a top cover with a male plug structure that mates with the top opening of the piston pressure chamber for insertion and removal. An anti-extrusion retaining ring and a fluororubber O-ring are installed in a groove below the plug structure. During test preparation and sample recovery, the pressure chamber can be quickly sealed and disassembled simply by inserting and removing the top cover, shortening the assembly time. When applying axial load for mechanical testing, the sliding displacement generated by the axially loaded piston pushes the self-locking ring downward, causing it to generate radial contraction and locking force along the inverted conical groove, tightly pressing and solidifying the latex sleeve of the sample. At the same time, the large displacement compression deformation of the sample is absorbed by the embedded chamber rail, keeping the sealing area at the end of the latex sleeve of the sample continuously fitted. In addition, the carbon fiber pad placed between the sample and the sample end cap, with an outer cylinder made of polyetheretherketone or titanium alloy, can remove the external heavy metal clamps during in-situ X-ray or neutron scanning tests, effectively eliminating the scattering interference of metal parts on the radiation and improving the non-destructive transmission rate of multiple beams. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the main structure of the vacuum confining pressure testing device involved in this invention.

[0047] Figure 2 This is a cross-sectional view of the main structure of the vacuum confining pressure testing device involved in the present invention.

[0048] Figure 3 This is an exploded view of the main structure of the vacuum confining pressure testing device involved in the present invention.

[0049] Figure 4 This is a schematic diagram of the upper part of the main structure of the vacuum confining pressure testing device involved in the present invention.

[0050] Figure 5 This is an exploded view of the upper part of the main structure of the vacuum confining pressure testing device involved in the present invention.

[0051] Figure 6 This is a schematic diagram of the lower part of the main structure of the vacuum confining pressure testing device involved in the present invention.

[0052] Figure 7 This is a cross-sectional view of the lower half of the main structure of the vacuum confining pressure testing device involved in the present invention.

[0053] Figure 8 This is an exploded view of the lower half of the main structure of the vacuum confining pressure testing device involved in this invention.

[0054] Figure 9 This is a schematic diagram showing the vacuum confining pressure testing device of the present invention in use. Detailed Implementation

[0055] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0056] Example 1:

[0057] The main structure of a vacuum confining pressure testing device involved in this embodiment is as follows: Figure 1-8 As shown, it includes a lower anvil 1, a central fluid injection conduit 2, a flange ring 3, a centering guide sleeve 4, a pore fluid injection interface 5, a lower O-ring 6, a sample 7, a sample end cap 8, a sample latex sleeve 9, a pad 10, an outer cylinder 11, a self-locking pressure ring 12, an embedded chamber rail 13, a bolt 14, a piston pressure chamber 15, an axially loaded piston 16, a top cover 17, a piston guide ring 18, a U-ring 19, an upper O-ring 20, a retaining ring assembly 21, a connector 22, and an exhaust valve 23;

[0058] The lower anvil 1 has a central fluid injection conduit 2 at the top center, a flange ring 3 around it, a centering guide sleeve 4 inside, and a pore fluid injection interface 5 outside.

[0059] The top of the central fluid injection conduit 2 is connected to the pore fluid injection interface 5, and a lower O-ring 6 is provided in the hollow part of the flange ring 3. A sample 7 is provided above the centering guide sleeve 4.

[0060] The top and bottom of the sample 7 are provided with sample end caps 8, the outer side is covered with sample latex sleeves 9, a pad block 10 is provided between the sample 7 and the sample end caps 8, and an outer cylinder 11 is provided on the outer side.

[0061] The outer side of the top of the latex sleeve 9 of the sample is fitted with a self-locking pressure ring 12, and the inner side is provided with an embedded compartment rail 13 that slides and cooperates with the top sample end cap 8.

[0062] The bottom of the outer cylinder 11 is connected to the lower anvil 1 via a flange ring 3 and bolts 14, and the top is connected to the piston pressure chamber 15. An axially loaded piston 16 is installed inside the piston pressure chamber 15, and a top cover 17 is installed on the top. A piston guide ring 18, a U-ring 19 and an upper O-ring 20 are installed on the guide part of the axially loaded piston 16, and a retaining ring assembly 21 is installed at the bottom of the top cover 17.

[0063] In addition, connectors 22 are provided on the outer sides of the lower anvil 1 and the top cover 17 to connect to an external control pump system. An exhaust valve 23 is provided on the outer cylinder 11 or the piston pressure chamber 15 to discharge residual air in the chamber when deionized water is filled into the outer cylinder 11 to contain the pressure medium.

[0064] In this embodiment, the lower anvil 1, outer cylinder 11 and piston pressure chamber 15 are closed to form a high-pressure fluid chamber. After the confining pressure is loaded by the external pump system, the high-pressure fluid chamber, together with the retaining ring assembly 21 at the top cover 17, forms a leak-free static pressure-holding structure, which realizes long-term stable pressure holding after the external pressure source is cut off.

[0065] Flange ring 3 is a locking and fixing flange ring, which is sealed and connected to the lower anvil seat 1 to form a base assembly;

[0066] The centering guide sleeve 4 is used to ensure that the axis of the axially loaded piston 16 is absolutely aligned with the center of the specimen 7;

[0067] The pore fluid injection interface 5 is used to inject high-salinity brine or supercritical carbon dioxide pore fluid into the sample latex sleeve 9.

[0068] Both the lower O-ring 6 and the upper O-ring 20 are fluororubber O-rings;

[0069] Sample 7 includes micro-particle samples and rock samples;

[0070] The sample end cap 8 is a sample end cap with an inverted conical groove, that is, an inverted conical groove structure is machined on its outer cylindrical surface. It works together with the sample latex sleeve 9, the self-locking pressure ring 12 and the embedded chamber rail 13 to form an adaptive rubber sleeve sealing assembly. The whole assembly is set inside the outer cylinder 11. The sample latex sleeve 9 wraps around the sample 7 and the sample end cap 8. The inner wall of the self-locking pressure ring 12 is provided with a conical surface adapted to the inverted conical groove and is sleeved on the outside of the sample latex sleeve 9. The embedded chamber rail 13 is a sliding annular or cylindrical support component, set at the end of the sample latex sleeve 9. Its outer circumference fits against the inner wall of the sample latex sleeve 9, and its inner circumference is sleeved on the outer circumferential guide surface of the sample end cap 8. It slides axially with the sample end cap 8 and has a sliding stroke along the axial direction. Its sliding direction is consistent with the loading direction of the axial loading piston 16, so that the axial settlement caused by the pressure of the sample 7 is compensated by the embedded chamber rail 13. The end sealing area of ​​the sample latex sleeve 9 is kept at the corresponding position of the sample end cap 8.

[0071] The pad 10 includes a carbon fiber pad for reducing the obstruction and scattering interference of metal components on X-rays or neutron beams within the scanning field of view;

[0072] The outer cylinder 11 is an integral confining pressure outer cylinder, made of materials including aluminum 7075-T6, polyether ether ketone, and high-strength titanium alloy. It is integrally molded to meet the requirements of extremely low attenuation and non-destructive penetration of high-energy synchrotron radiation sources or neutron beams, so as to maximize the transmittance of multiple beams while ensuring the confining pressure bearing capacity of hundreds of megapascals. Its corresponding wall thickness in the scanning area of ​​sample 7 is 4 mm.

[0073] The self-locking pressure ring 12 is a floating self-locking pressure ring. It achieves passive adaptive diameter reduction through mechanical extrusion. Under the premise of avoiding physical interference from traditional large external clamps, it achieves high airtightness and tight wrapping of the micro-scale sample 7, meeting the spatial limitation requirements of micro-distance high-resolution tomography.

[0074] The piston pressure chamber 15 and the top cover 17 work together to form a quick-release assembly. The top cover 17 has a plug-in structure and is inserted into the top opening of the guide flange of the piston pressure chamber 15, so as to realize the quick closing and disassembly of the top of the piston pressure chamber 15. The top cover 17 has a male plug-in structure. A groove is provided below the male plug-in structure. A retaining ring assembly 21 including a fluororubber O-ring is installed in the groove to prevent the top cover 17 from being squeezed out, so as to achieve the anti-extrusion seal of high pressure fluid in the closed state. The outer contour of the male plug-in structure is adapted to the top opening of the piston pressure chamber 15.

[0075] The piston guide ring 18 is an SKF piston guide ring, and a polyurethane U-ring 19 is installed in the upper hole. A retaining ring assembly 21 is installed in the continuous groove of the piston channel to jointly ensure high-pressure sealing during the sliding process.

[0076] Connector 22 is a high-pressure connector.

[0077] The sample involved in this embodiment is a small-sized simulated soil and rock sample. Accordingly, the diameter of the sample end cap 8 is 20 mm, the length of the sample latex sleeve 9 is 50 mm, and the thickness of the pad 10 is 5 mm.

[0078] Example 2:

[0079] When using the vacuum confining pressure testing device described in this embodiment, such as... Figure 9 As shown, the clamping device 31 is connected to the gas source 33 via a pipe 32. A flexible heating / cooling module 35, connected to a chiller 34, is installed on the outer wall of the clamping device 31. A high-vacuum isolation valve 36 and a fine-tuning needle valve 37 are sequentially arranged along the flow direction on the pipe 32. A multi-parameter data acquisition module 38 is electrically connected to various sensors installed on the clamping device 31 and the pipe 32. These components work together to form an extreme environment multi-field coupling in-situ testing system based on synchrotron radiation, capable of high-precision testing of small particulate samples under micro-positive pressure loading and negative pressure suction environments. The system features airtight sealing and in-situ compression observation. By controlling the extremely low flow rate through a fine-tuning needle valve, a splash-proof test environment can be established. Through the linkage between the multi-parameter data acquisition module and the shutter signal of the synchrotron radiation beamline detector, the mechanical parameters and in-situ three-dimensional microscopic evolution images of the corresponding sample under extreme temperature and pressure environments can be acquired synchronously and accurately. By placing the clamping device 31 in the detection optical path of the synchrotron radiation beamline or X-ray source, in-situ non-destructive detection and imaging of the multi-physics compression process of small particulate samples or rock samples under complex temperature and pressure and specific temperature, confining pressure, atmosphere or vacuum conditions can be achieved.

[0080] When testing with powdered lunar soil simulants or tiny rocks as sample 7, the specific steps are as follows:

[0081] S1. First, insert the sample 7 into the sample latex sleeve 9, and assemble the pads 10 and sample end caps 8 at both ends of the sample 7. Then, put the self-locking pressure rings 2-6 on the outside of the sample latex sleeve 9.

[0082] Then, the assembled sample 7 is placed on the centering guide sleeve 4, and the outer cylinder 11 and piston pressure chamber 15 are put on in sequence.

[0083] Finally, insert the top cover 17 into the piston pressure chamber 15 to complete the quick locking assembly of the test chamber;

[0084] S2. First, open the exhaust valve 23 and the high vacuum isolation valve 36, and adjust the fine-tuning needle valve 37 to the slow pumping position.

[0085] Then, turn on the external vacuum pump connected to the pipeline 32, and slowly evacuate the vacuum by adjusting the needle valve 37 to prevent the sample 7 from splashing, until the set vacuum level is reached.

[0086] Finally, turn off the vacuum pump, open the high vacuum isolation valve 36, and slowly fill the protective gas supplied by the gas source 33 through the fine-tuning needle valve 37.

[0087] S3. First, open the exhaust valve 23 and the external confining pressure pump;

[0088] Then, the confining pressure pump pumps deionized water medium into the clamping device 31 through the connector 22. When fluid steadily overflows from the exhaust valve 23, the exhaust valve screw 23 is closed, and the confining pressure in the clamping device 31 is applied to the set value and maintained by the confining pressure pump.

[0089] Finally, turn on the chiller 34 and the flexible heating / cooling module 35 to adjust the temperature of the clamping device 31 until the sample 7 reaches the simulated extreme thermal environment conditions on the lunar surface.

[0090] S4, drive the axially loaded piston 16 to move downward.

[0091] When the axial loading piston 16 is loaded downward, its end abuts against and pushes the self-locking pressure ring 12 downward to lock the end of the sample latex sleeve 9, forcing the self-locking pressure ring 12 to generate radial contraction locking force along the inverted conical groove, thereby tightly pressing and fixing the sample latex sleeve 9 onto the sample end cap 8, and applying axial deformation load to the sample 7. When the sample 7 undergoes large compression settlement, the embedded chamber rail 13 slides and absorbs the axial settlement displacement during the compression process of the sample 7, so as to keep the end sealing area of ​​the sample latex sleeve 9 corresponding to the sample end cap 8 and maintain their continuous fit.

[0092] Simultaneously, the multi-parameter data acquisition module 38 is activated to continuously acquire data such as loading force, lateral pressure, temperature, and vacuum degree. When the axial deformation reaches the set imaging node, the multi-parameter data acquisition module 38 receives and responds to the shutter signal of the synchrotron radiation beamline detector, aligns the timestamp of the multidimensional thermodynamic data with the precise timestamp of the X-ray tomography imaging, and completes the data recording.

[0093] S5. First, slowly reduce the axial thrust to zero;

[0094] Then, turn off the chiller 34 and the flexible heating / cooling module 35, wait for the clamping device 31 to slowly return to room temperature, reduce the pressure of the external confining pressure pump to zero, and open the exhaust valve 23 and the corresponding connector 22 to drain the liquid medium.

[0095] Finally, the top cover 17 was pulled out, and the piston pressure chamber 15 and outer cylinder 11 were removed in sequence. The deformed sample 7 was then taken out for further offline analysis.

[0096] Among them, the gas source 33 includes a high-pressure inert gas cylinder, which provides nitrogen or helium for system repressurization, protective atmosphere construction or specific environment reconstruction;

[0097] The flexible heating / cooling module 35 is physically attached to the outer wall of the clamping device 31. The chiller 34 provides it with a deep-cooling or heating circulating medium. By utilizing the efficient heat conduction of the metal cylinder wall, an extremely cold or extremely hot environment is quickly established inside the clamping device 31 to simulate the real temperature field of the lunar surface.

[0098] The fine-tuning needle valve 37 is a high-precision slow-pump valve. When reconstructing a specific environment, it can control the gas flow rate in minute quantities to achieve slow vacuuming, establishing negative pressure, or slow gas filling for micro-positive pressure repressurization, thus preventing physical splashing of the sample 7 (especially powdered samples) under transient strong airflow disturbances. When establishing a preset negative pressure or micro-positive pressure environment for the powdered micro sample 7, it can control the flow rate at extremely low speeds to prevent airflow splashing of the sample.

[0099] The multi-parameter data acquisition module 38 can accurately simulate extreme environments such as high and low temperatures on the lunar surface by adjusting the temperature control medium during multi-physics coupling experiments. Through direct linkage with the shutter signal of the synchrotron radiation beamline detector, it can synchronously and accurately acquire the mechanical and thermal parameters of the sample 7 during the compression process, as well as the response and three-dimensional structural evolution information of the in-situ three-dimensional scanning structural image. The multi-parameter data acquisition module 38 can also be linked and aligned with the detector and shutter signal of the synchrotron radiation beamline or X-ray source to realize synchronous spatial mapping of extreme physical field evolution data and dynamic imaging of microscopic three-dimensional structures. It can synchronously integrate and acquire multi-dimensional experimental data such as loading force (F), lateral pressure (PL), temperature (T), and force sensor, lateral pressure sensor, temperature sensor and vacuum degree (VG) of pipeline 32 in real time.

Claims

1. A vacuum confining pressure testing device, characterized in that, The main structure includes a base assembly, an integrated confining outer cylinder, a quick-release assembly, an axially loaded piston, and an adaptive rubber sleeve sealing assembly; The adaptive rubber sleeve sealing assembly is located inside the integrated confining pressure outer cylinder to enclose the sample; The axially loaded piston passes axially through the quick-release assembly, and its bottom end abuts against the adaptive rubber sleeve sealing assembly; The lower end of the integrated confining pressure outer cylinder is fixed to the base assembly, the upper end is connected to the quick-release assembly, and forms the upper wall of the low-attenuation cylinder at least in the corresponding sample scanning area. The upper end of the base assembly is sealed to the outer cylinder of the integrated confining pressure chamber, and forms a low-attenuation cylinder at least in the scanning area of ​​the corresponding sample.

2. The vacuum confining pressure testing device according to claim 1, characterized in that, The base assembly includes a lower anvil and a locking flange ring.

3. The vacuum confining pressure testing device according to claim 2, characterized in that, The quick-release assembly includes a piston pressure chamber and a top cover. The top cover is inserted into the piston pressure chamber via a plug-in engagement. The piston pressure chamber is fixed to the top of the integrated outer cylinder of the pressure chamber. The top cover has a male plug structure, and its outer contour is adapted to the top opening of the piston pressure chamber. A groove is provided below the plug structure of the top cover, and a top cover anti-extrusion retaining ring and a fluororubber O-ring are installed in the groove.

4. The vacuum confining pressure testing device according to claim 3, characterized in that, The adaptive rubber sleeve sealing assembly includes a sample latex sleeve, a sample end cap with an inverted conical groove, a floating self-locking pressure ring, and a sliding embedded chamber rail located on the inner side of the end of the sample latex sleeve. The sample end caps are respectively located at both ends of the sample, and an inverted conical groove structure is machined on the outer cylindrical surface. The sample latex sleeve wraps around the sample and the sample end cap. The self-locking pressure ring is sleeved on the outside of the sample latex sleeve, and its initial position corresponds to the sample end cap. The embedded chamber rail is a ring or cylindrical support component, with its outer circumference fitting against the inner wall of the end of the sample latex sleeve, and its inner circumference sleeved against the outer circumferential guide surface of the sample end cap, and it slides axially with the sample end cap, having a sliding stroke along the axial direction.

5. The vacuum confining pressure testing device according to claim 4, characterized in that, A carbon fiber pad is horizontally placed between the sample and the sample end cap.

6. A vacuum confining pressure testing device according to any one of claims 1-5, characterized in that, The materials used for the outer casing of the integrated confining pressure chamber include polyetheretherketone (PEEK) and titanium alloy.

7. A vacuum confining pressure testing device according to claim 3 or 4, characterized in that, When an axial load is applied, the axial loading piston slides downward, abutting and pushing the self-locking ring, forcing the self-locking ring to generate radial contraction and locking force along the inverted conical groove. Simultaneously, the sample is pressurized and the adaptive rubber sleeve sealing assembly is mechanically squeezed, locking and pushing the self-locking ring to lock the end of the latex sleeve of the sample. At the same time, the axial settlement displacement during the sample compression process is compensated by the embedded chamber rail.

8. A vacuum confining pressure testing device according to claim 3 or 4, characterized in that, In use, it serves as a clamping device, connected to the atmosphere and fluid control pipelines. Together with a flexible heating / cooling module, chiller, multi-parameter data acquisition module, and synchrotron radiation beamline detector, it forms a multi-field coupled in-situ testing system for extreme environments based on synchrotron radiation. It performs multi-field coupled in-situ scanning and testing of samples in extreme environments, supporting dynamic in-situ joint testing on a synchrotron radiation CT scanning workbench while rotating, loading at a constant strain rate, and performing online CT scanning. Through parallel fine-tuning of the slow extraction path and multi-mode interchangeable chamber design, it takes into account high vacuum mode, micro-positive pressure loading, negative pressure environment construction, and displacement compensation of the embedded chamber rail. This enables the multi-functional expansion requirements of loose particle samples to prevent fluidization, control temperature and water retention, and perform routine testing of deep-earth rocks at 100 MPa high confining pressure. It also maintains the sealing stability of the rubber sleeve end during large deformation compression. Through the DAQ-TTL collaborative triggering architecture, it achieves alignment of force, deformation, local temperature field, and high vacuum data with the absolute time timestamp of the synchrotron radiation exposure shutter frame by frame.

9. A vacuum confining pressure testing device according to claim 8, characterized in that, The atmosphere and fluid control pipeline includes a high-purity inert gas cylinder, a high-vacuum isolation valve, and a fine-tuning needle valve. The high-purity inert gas cylinder is connected to the clamping device in sequence through the high-vacuum isolation valve and the fine-tuning needle valve. A flexible heating / cooling module is enclosed on the outside of the clamping device; The chiller is connected to the flexible heating / cooling module to provide it with circulating cooling medium; The multi-parameter data acquisition module is electrically connected to various sensors installed on the clamping device and the atmosphere and fluid control lines.

10. A vacuum confining pressure testing device according to claim 3 or 4, characterized in that, The specific process for testing the displacement, steady-state, and transient permeability of low-permeability rock samples includes the following steps: S1. Sample packaging and device assembly First, place the sample inside the sample latex sleeve, assemble the sample end caps and pads at its upper and lower ends, and fit the embedded compartment rail and self-locking pressure ring on the outside of the sample latex sleeve. Then, the assembled sample is installed on the lower anvil, and the outer cylinder and piston pressure chamber are inserted in sequence. Finally, the top cover is inserted into the improved piston pressure chamber to complete the quick-release locking, and the axially loaded piston is driven to press the self-locking pressure ring downward. S2, Vacuuming and Atmosphere Reconstruction First, close the exhaust valve and high vacuum isolation valve on the clamping device that are connected to the outside world; Then, open the fine-tuning needle valve and adjust it to the slow-pulse setting; Finally, turn on the external vacuum pump and slowly evacuate the inside of the clamping device through the fine-tuning needle valve until the set standard is reached. Then, turn off the vacuum pump, open the high vacuum isolation valve, adjust the fine-tuning needle valve, establish negative pressure, and fill with inert gas. S3. Apply confining pressure and control temperature. Open the exhaust valve and the external confining pressure pump to pump fluid medium into the clamping device. Once fluid flows out of the exhaust valve, close the exhaust valve and continue to use the external confining pressure pump to apply confining pressure to the clamping device until the set conditions are met. Start the chiller and flexible heating / cooling module to heat or cool the clamping device until the sample temperature reaches the preset lunar extreme thermal environment conditions. S4, In-situ Axial Compression Displacement and Synchronous Scanning An axial load is applied to the sample by an axial loading piston to perform axial compression load. During the compression process, the embedded chamber rail slides with the axial settlement of the sample to maintain the end seal of the sample latex sleeve. When the axial loading piston moves downward, it pushes the self-locking pressure ring, causing the self-locking pressure ring to generate radial contraction locking force along the inverted conical groove of the sample end cap. The embedded chamber rail slides axially along the outer peripheral guide surface of the sample end cap to reduce the pull of the sample compression settlement on the end seal area of ​​the sample latex sleeve. Simultaneously, the multi-parameter data acquisition module is activated to collect data on loading force, lateral pressure mechanics, temperature, pipeline, and vacuum in real time. At the set deformation node, the shutter signal emitted by the synchrotron radiation beamline detector is received. The mechanical and thermal data are precisely aligned with the timestamp of the X-ray tomographic imaging obtained synchronously through the multi-parameter data acquisition module to obtain the three-dimensional evolution image of the sample in situ. S5. Pressure relief and sample recovery First, reduce the axial load to zero, turn off the chiller and flexible heating / cooling module, and allow the clamping device to return to room temperature; Then, reduce the pressure of the external confining pressure pump to zero and open the corresponding pipeline to discharge the fluid medium; Finally, the top cover was removed, the piston pressure chamber and outer cylinder were taken out, and the sample was removed for data analysis.

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