Sample deformation measurement system for in-situ CT imaging super-high temperature mechanical loading experiment

Abstract

The application provides a sample deformation measurement system for in-situ CT imaging of ultrahigh-temperature mechanical loading experiments, adopts high-temperature ceramic material as auxiliary lead-out design, leads out the deformation of the sample gauge length section to outside of a high-temperature furnace and uses LVDT to measure; meanwhile, in order to eliminate the influence of the deformation of the X-ray transmission thin wall in the high-temperature furnace on the sample deformation measurement, the application also uses a video extensometer to monitor the thin wall deformation in real time, and corrects the LVDT measurement result according to the data, so that high-precision deformation measurement under ultrahigh-temperature environment is realized; the measurement system can be compatible with high-resolution in-situ CT imaging experiments, meets the requirement of simultaneously performing mechanical loading and microstructure imaging under high-temperature environment, improves the real-time performance and precision of in-situ experiments, and provides a powerful tool for comprehensively studying the mechanical properties and behaviors of materials, so as to meet the requirement of comprehensively and deeply studying the properties and behaviors of materials, and make up for the blank of the prior art.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature mechanical testing technology, and in particular relates to a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments. Background Technology

[0002] With the rapid development of aerospace, nuclear energy, and automotive industries, materials capable of stable operation in ultra-high temperature environments have gradually become a research focus. For example, ceramic matrix composites, high-temperature alloys, and silicon carbide are widely used in high-temperature working environments. The mechanical properties of these materials at high temperatures directly affect their service reliability; therefore, testing and characterizing their mechanical properties under high-temperature conditions is particularly important. Traditional high-temperature mechanical property testing methods, such as tensile, compression, and bending experiments, typically obtain the basic mechanical parameters of the material by measuring the relationship between load and displacement. However, these methods mainly focus on macroscopic mechanical behavior and are difficult to observe in depth the changes in the material's internal microstructure, such as crack propagation, pore evolution, and the movement of lattice defects.

[0003] In recent years, X-ray computed tomography (CT) technology has been widely used in the study of the internal structure of materials due to its ability to perform three-dimensional non-destructive testing. Compared with traditional mechanical testing methods, in-situ CT imaging combined with mechanical loading experiments can observe the evolution of the internal microstructure of materials in real time during loading. This method provides dynamic, high-resolution three-dimensional images, which helps to reveal microscopic mechanisms such as crack initiation and propagation, pore formation and merging, and interface damage.

[0004] In in-situ CT imaging experiments with ultra-high temperature mechanical loading, accurate monitoring of specimen deformation is crucial for analyzing the high-temperature mechanical behavior of materials. However, monitoring specimen deformation in ultra-high temperature environments presents a series of challenges. First, some traditional displacement measurement methods (such as external LVDT sensors) suffer from significant errors when measured outside a high-temperature furnace due to interference from temperature gradients and thermal deformation of the components within the furnace. Second, in small high-temperature furnaces used in conjunction with high-resolution in-situ CT, the confined operating space and ultra-high temperature environment can cause complex thermal interference to the sensors and deformation measurement devices, leading to malfunctions due to material degradation or electromagnetic radiation interference, significantly reducing measurement accuracy and stability. Furthermore, in-situ CT imaging requires unobstructed three-dimensional scanning of the sample and loading device within the X-ray beam's field of view, placing stringent demands on the deformation measurement device's structure: it must be compact, minimize X-ray absorption or scattering, and avoid complex mechanical components obstructing the CT imaging field of view. Finally, during in-situ CT imaging, changes in the material's internal microstructure need to be characterized through high-resolution three-dimensional reconstruction. Large measurement errors in sample deformation directly affect imaging quality and the accuracy of subsequent analysis; therefore, high measurement accuracy is required for the deformation measurement device.

[0005] Therefore, overcoming the above-mentioned technical challenges and developing a high-precision sample deformation measurement system and method that can be used for in-situ CT imaging ultra-high temperature mechanical loading experiments is not only of great scientific significance, but also of extremely important application value for improving the accuracy and reliability of materials research. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments. By optimizing the sensor layout, introducing high-temperature resistant materials, and employing LVDT measurement technology, it is possible to achieve accurate measurement of sample deformation in a small-sized, sealed, high-temperature environment.

[0007] A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments is applied to a high-temperature furnace system based on in-situ CT imaging. The sample deformation measurement system includes a host computer, a loading device 1, an extraction measurement device, and four video extensometers 7 arranged at 90-degree intervals around the high-temperature furnace system, with the video extensometers facing the X-ray transmission thin-walled flange 5. The sample to be tested is installed in the middle section of the extraction measurement device. The high-temperature furnace system is used to provide different temperature environments for the sample to be tested 22, and is assembled sequentially from an upper furnace body 4, an X-ray transmission thin-walled flange 5, and a lower furnace body 6.

[0008] The lead-out measuring device enters the high-temperature furnace system from the top of the upper furnace body 4 and exits the high-temperature furnace system from the bottom of the lower furnace body 6, so that the test sample is located in the middle section of the high-temperature furnace system, and the test sample 22 can be scanned by X-rays transmitted from the X-ray transmission thin-walled flange 5.

[0009] The loading device 1 is used to connect to the upper end of the lead-out measuring device, thereby applying a tensile load to the test sample 22 until the test sample 22 breaks, and using in-situ CT imaging technology to perform X-ray scanning imaging of the deformation process of the test sample 22 from the X-ray transmission thin-walled flange 5; at the same time, the lead-out measuring device is used to measure the displacement generated during the deformation process of the test sample 22.

[0010] The four video extensometers 7 measure the displacement of the thin-walled flange 5 during the deformation of the test sample 22 from four different directions, respectively;

[0011] The host computer is used to perform three-dimensional reconstruction of the deformation process of the test sample 22 based on the X-ray scanning imaging results, and to determine the deformation amount of the test sample 22 based on the displacement of the test sample 22 and the displacement generated by the X-ray transmission thin-walled flange 5.

[0012] Furthermore, the extraction measuring device includes an upper deformation extraction measuring component 3 installed in the upper furnace body 4 and a lower deformation extraction measuring component 8 installed in the lower furnace body 6, and the test sample is connected between the upper deformation extraction measuring component 3 and the lower deformation extraction measuring component 8.

[0013] The upper deformation lead-out measuring assembly 3 includes an upper pull head 11, an upper lead-out rod 21, an upper mounting cover 13, two upper LVDT assemblies, and two upper core screws 20. The upper mounting cover 13 is mounted on the upper end face of the upper furnace body 4. The two upper LVDT assemblies are installed in the mounting holes of the upper mounting cover 13 and fixed by screws inserted into the screw holes on the side of the upper mounting cover 13. The upper lead-out rod 21 has a hollow cylindrical structure and an outwardly extending first annular mounting lug at its upper end. The two upper core screws 20 are respectively screwed into the screw holes on the first annular mounting lug, and one end of each upper core screw 20 extending out of the screw hole is threaded onto one of the two upper LVDT assemblies. The upper pull-out rod 21 is connected to the upper furnace body 4. Simultaneously, the upper pull-out rod 21 passes through a through-hole on the upper end face of the upper furnace body 4, causing it to be locked in place by its own weight at the variable-diameter surface of the upper pull head 11 fitted inside the upper pull-out rod 21. The lower end of the upper pull head 11 also passes through a through-hole on the upper end face of the upper furnace body 4 and is connected to the test sample. The upper end of the upper pull head 11 extends from between the two upper LVDT assemblies through the upper mounting cover 13 and is then connected to the loading device 1. The loading device 1 applies a tensile load to the test sample via the upper pull head 11. The two upper LVDT assemblies are used to measure the displacement generated during the deformation of the test sample.

[0014] The lower deformation lead-out measuring assembly 8 includes a pull-down head 17, a lower lead-out rod 23, a lower mounting cover 14, two lower LVDT assemblies, and two lower core screws. The lower mounting cover 14 is installed on the lower end face of the lower furnace body 6. The two lower LVDT assemblies are installed in the mounting holes of the lower mounting cover 14 and fixed by screws inserted into the screw holes on the side of the lower mounting cover 14. The lower lead-out rod 23 has a hollow cylindrical structure with a second outwardly extending annular mounting lug at the lower end and a third inwardly extending annular mounting lug at the upper end. The two lower core screws are screwed into the screw holes on the second annular mounting lugs, and one end of each lower core screw extending out of the screw hole is threadedly connected to one of the two lower LVDT assemblies. Simultaneously, the lower lead-out rod 23 passes through the lower furnace body. The through hole on the lower end face of body 6 penetrates into the interior of lower furnace body 6, allowing the lower lead-out rod 23 to be secured by its own weight through the third ring mounting lug at the variable diameter surface of the pull-down head 17 fitted inside the lower lead-out rod 23. The upper end of the pull-down head 17 also penetrates into the interior of lower furnace body 6 through the through hole on the lower end face of lower furnace body 6, and the upper end of the pull-down head 17 provides tensile load to the pull-down head 17 by connecting to the test sample. The lower end of the pull-down head 17 extends out of the lower mounting cover 14 between the two lower LVDT assemblies. A locking nut is installed at the lower end of the pull-down head 17, which can be locked on the lower end face of the lower mounting cover 14 during the tensile test to restrict the upward movement of the pull-down head 17. The two lower LVDT assemblies are used to measure the displacement generated during the deformation of the test sample.

[0015] Furthermore, a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments also includes an upper cover plate 12 and a lower cover plate 15.

[0016] The upper cover plate 12 is used to enclose the upper mounting cover 13, and the lower cover plate 15 is used to enclose the lower mounting cover 14.

[0017] Furthermore, water-cooling pipe heads are also provided on the upper mounting cover 13 and the lower mounting cover 14;

[0018] The water-cooled pipe head is used to introduce cold water, which is used to control the operating temperature of the upper LVDT component and the lower LVDT component to maintain within a set range.

[0019] Furthermore, a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments also includes a column 2;

[0020] The loading device 1 is installed on the upper end face of the upper furnace body 4 via the column 2.

[0021] Furthermore, the method by which the host computer determines the deformation of the test sample based on the displacement of the test sample and the displacement generated by the X-ray transmission thin-walled flange 5 is as follows:

[0022] During the stretching stage, the deformation is calculated as follows: the difference between the average displacement measured by the two upper LVDT components and the average displacement measured by the two lower LVDT components is obtained; the average displacement of the X-ray transmission thin-walled flange 5 measured by the four video extensometers 7 is obtained; and the difference between the difference and the average displacement of the X-ray transmission thin-walled flange 5 is taken as the deformation.

[0023] During the load holding phase, the deformation is the difference between the average displacement measured by the two upper LVDT components and the average displacement measured by the two lower LVDT components.

[0024] Furthermore, the method for obtaining the average displacement of the X-ray transmission thin-walled flange 5 measured by the four video extensometers 7 is as follows:

[0025] Place one mark at the top and one at the bottom of the vertical direction of the X-ray transmission thin-walled flange 5, with a total of four sets placed at 90-degree intervals;

[0026] Adjust the camera position and focal length of each video extensometer 7 so that each video extensometer 7 is aligned with a set of marks, ensuring that the marks are visible in the video;

[0027] Each video extensometer 7 collects the distance change corresponding to each group of marks during the deformation of the test sample;

[0028] The average value of the distance change between two marks in the four sets of marks is taken as the average value of the displacement of the thin-walled flange 5 in X-ray transmission.

[0029] Furthermore, the method by which the loading device 1 applies a tensile load to the test sample until the test sample breaks is as follows:

[0030] S1: The high-temperature furnace system heats the test sample 22 until the temperature reaches the set value, then the loading device 1 applies a tensile load to the test sample 22; the lead-out measuring device is used to measure the displacement generated during the deformation of the test sample 22; the video extensometer 7 is used to measure the displacement generated by the X-ray transmission thin-walled flange 5.

[0031] S2: After the loading device 1 applies a tensile load to the test sample 22 to the set value, it keeps the tensile load unchanged. At this time, in-situ CT imaging technology is used to perform X-ray scanning imaging of the deformation process of the test sample 22 from the X-ray transmission thin-walled flange 5.

[0032] S3: Repeat steps S1 and S2 until the test sample 22 breaks, and obtain the X-ray scanning image and deformation of the test sample during the entire tensile process.

[0033] Furthermore, a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments also includes a turntable 9;

[0034] The turntable 9 is used to support the high-temperature furnace system and rotates the lead-out measuring device integrated with the high-temperature furnace system during the stage when the tensile load remains unchanged, so as to perform X-ray scanning imaging of the test sample from different perspectives.

[0035] Beneficial effects:

[0036] This invention provides a specimen deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments. It employs a high-temperature ceramic material as an auxiliary extraction design to extract the specimen gauge length deformation outside the high-temperature furnace and measure it using a video extensometer (LVDT). Simultaneously, to eliminate the influence of X-ray transmission through the thin wall deformation inside the high-temperature furnace on the specimen deformation measurement, this invention also uses a video extensometer to monitor the thin wall deformation in real time and corrects the LVDT measurement results based on the data, achieving high-precision deformation measurement under ultra-high temperature conditions. The measurement system of this invention is compatible with high-resolution in-situ CT imaging experiments, meeting the need for simultaneous mechanical loading and microstructural imaging under high-temperature conditions, improving the real-time performance and accuracy of in-situ experiments. This system is applicable to various high-temperature in-situ experiments such as tension, compression, shear, bending, and indentation, providing a powerful tool for comprehensively studying the mechanical properties and behavior of materials, satisfying the need for comprehensive and in-depth research on material properties and behavior, and filling a gap in existing technologies. Attached Figure Description

[0037] Figure 1 This is a front view schematic diagram of a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments provided by the present invention;

[0038] Figure 2 This invention provides a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments;

[0039] Figure 3 A front view schematic diagram of the deformation extraction measuring device provided by the present invention;

[0040] Figure 4 A two-dimensional isometric schematic diagram of the deformation extraction measuring device provided by the present invention;

[0041] Figure 5 A two-dimensional cross-sectional schematic diagram of the deformation extraction measuring device provided by the present invention;

[0042] Figure 6 A three-dimensional cross-sectional schematic diagram of the deformation extraction measuring device provided by the present invention;

[0043] Figure 7 Another two-dimensional cross-sectional schematic diagram of the deformation extraction measuring device provided by the present invention;

[0044] Figure 8A schematic diagram of the LVDT component provided by the present invention;

[0045] Figure 9 An isometric schematic diagram of an embodiment of the LVDT mounting cover provided by the present invention;

[0046] 1-Loading device, 2-Column, 3-Upper deformation lead-out measurement assembly, 4-Upper furnace body, 5-X-ray transmission thin-walled flange, 6-Lower furnace body, 7-Video extensometer, 8-Lower deformation lead-out measurement assembly, 9-Turntable, 10-Pull rod, 11-Upper pull head, 12-Upper cover plate, 13-Upper mounting cover, 14-Lower mounting cover, 15-Lower cover plate, 16-Locking nut, 17-Lower pull head, 18-LVDT housing, 19-LVDT core, 20-Core screw, 21-Upper lead-out rod, 22-Test sample, 23-Lower lead-out rod, 24-Signal connector socket, 25-Water cooling pipe port, 26-Screw hole, 27-LVDT housing mounting hole. Detailed Implementation

[0047] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0048] like Figure 1 and Figure 2 As shown, a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments is applied to a high-temperature furnace system based on in-situ CT imaging. The sample deformation measurement system includes a host computer, a loading device 1, a column 2, a turntable 9, an extraction measurement device, and four video extensometers 7 arranged at 90-degree intervals around the high-temperature furnace system, with the video extensometers facing the X-ray transmission thin-walled flange 5. The sample to be tested is installed in the middle section of the extraction measurement device. The high-temperature furnace system is used to provide different temperature environments for the sample to be tested 22, and is assembled sequentially from an upper furnace body 4, an X-ray transmission thin-walled flange 5, and a lower furnace body 6.

[0049] like Figure 3 and Figure 4 As shown, the lead-out measuring device enters the high-temperature furnace system from the top of the upper furnace body 4 and exits the high-temperature furnace system from the bottom of the lower furnace body 6, so that the test sample is located in the middle section of the high-temperature furnace system, and the test sample 22 can be scanned by X-rays transmitted from the X-ray transmission thin-walled flange 5.

[0050] The loading device 1 is used to connect to the upper end of the lead-out measuring device, thereby applying a tensile load to the test sample 22 until the test sample 22 breaks, and using in-situ CT imaging technology to perform X-ray scanning imaging of the deformation process of the test sample 22 from the X-ray transmission thin-walled flange 5; at the same time, the lead-out measuring device is used to measure the displacement generated during the deformation process of the test sample 22.

[0051] The four video extensometers 7 measure the displacement of the thin-walled flange 5 during the deformation of the test sample 22 from four different directions, respectively;

[0052] The host computer is used to perform three-dimensional reconstruction of the deformation process of the test sample 22 based on the X-ray scanning imaging results, and to determine the deformation amount of the test sample 22 based on the displacement amount of the test sample 22 and the displacement amount generated by the X-ray transmission thin-walled flange 5.

[0053] The loading device 1 is installed on the upper end face of the upper furnace body 4 via the column 2;

[0054] The turntable 9 is used to support the high-temperature furnace system and rotates the lead-out measuring device integrated with the high-temperature furnace system during the stage when the tensile load remains unchanged, so as to perform X-ray scanning imaging of the test sample from different perspectives.

[0055] Furthermore, the sample deformation measurement system also includes an upper cover plate 12 and a lower cover plate 15; the extraction measurement device includes an upper deformation extraction measurement component 3 installed in the upper furnace body 4 and a lower deformation extraction measurement component 8 installed in the lower furnace body 6, and the sample to be tested is connected between the upper deformation extraction measurement component 3 and the lower deformation extraction measurement component 8.

[0056] like Figures 5-7 As shown, the upper deformation lead-out measuring assembly 3 includes an upper pull head 11, an upper lead-out rod 21, an upper mounting cover 13, two upper LVDT assemblies, and two upper core screws 20; wherein, the upper mounting cover 13 is installed on the upper end face of the upper furnace body 4; the two upper LVDT assemblies are installed in the mounting holes of the upper mounting cover 13 and are fixed by screws inserted into the screw holes on the side of the upper mounting cover 13; the upper cover plate 12 is used to enclose the upper mounting cover 13; the upper lead-out rod 21 is a hollow cylindrical structure, and the upper end is provided with an outwardly extending first annular mounting lug; as Figure 8 As shown, two upper core screws 20 are screwed into the screw holes on the first ring mounting lug, and one end of each upper core screw 20 protruding from the screw hole is threadedly connected to the two upper LVDT assemblies. At the same time, the upper lead-out rod 21 passes through the through hole on the upper end face of the upper furnace body 4 and enters the interior of the upper furnace body 4. The upper lead-out rod 21 is stuck at the variable diameter surface of the upper pull head 11 fitted inside the upper lead-out rod 21 due to its own weight. The lower end of the upper pull head 11 also passes through the through hole on the upper end face of the upper furnace body 4 and enters the interior of the upper furnace body 4, and is connected to the test sample. The upper end of the upper pull head 11 passes through the upper mounting cover 13 between the two upper LVDT assemblies and is then connected to the loading device 1. The loading device 1 applies a tensile load to the test sample through the upper pull head 11. The two upper LVDT assemblies are used to measure the displacement generated during the deformation of the test sample.

[0057] The lower deformation lead-out measuring assembly 8 includes a pull-down head 17, a lower lead-out rod 23, a lower mounting cover 14, two lower LVDT assemblies, and two lower core screws. The lower mounting cover 14 is installed on the lower end face of the lower furnace body 6. The two lower LVDT assemblies are installed in the mounting holes of the lower mounting cover 14 and fixed by screws inserted into the screw holes on the side of the lower mounting cover 14. The lower cover plate 15 is used to enclose the lower mounting cover 14. The lower lead-out rod 23 has a hollow cylindrical structure, with a second outwardly extending annular mounting ear at the lower end and a third inwardly extending annular mounting ear at the upper end. The two lower core screws are screwed into the screw holes on the second annular mounting ears, and one end of each lower core screw protruding from the screw holes is threadedly connected to the two lower LVDT assemblies. Simultaneously, the lower lead-out rod... The lower lead rod 23 passes through the through hole on the lower end face of the lower furnace body 6 and enters the interior of the lower furnace body 6. Due to its own weight, the lower lead rod 23 is locked at the variable diameter surface of the pull-down head 17, which is fitted inside the lower lead rod 23, through the third ring mounting ear. The upper end of the pull-down head 17 also passes through the through hole on the lower end face of the lower furnace body 6 and enters the interior of the lower furnace body 6. The upper end of the pull-down head 17 provides tensile load to the pull-down head 17 by connecting to the test sample. The lower end of the pull-down head 17 passes through the lower mounting cover 14 between the two lower LVDT assemblies. A locking nut is installed at the lower end of the pull-down head 17, which can be locked on the lower end face of the lower mounting cover 14 during the tensile test to restrict the upward movement of the pull-down head 17. The two lower LVDT assemblies are used to measure the displacement generated during the deformation of the test sample.

[0058] In other words, the upper lead-out rod 21 and the lower lead-out rod 23 are respectively fitted onto the outer side 11 of the upper pull head and the outer side 17 of the lower pull head; the lower end face of the upper lead-out rod 21 is stuck at the variable diameter surface of the upper pull head 11 due to gravity; the constricted inner surface of the lower lead-out rod 23 is stuck at the variable diameter surface of the lower pull head 17 due to gravity; one end of the LVDT core 19 is connected to the corresponding upper lead-out rod 21 or lower lead-out rod 23 by a screw 20, and the other end is inserted into the LVDT housing 18, allowing for telescopic movement; the LVDT assembly can transmit displacement data through the signal line plugged into the signal connector socket 24 of the mounting cover.

[0059] It should be noted that, as Figure 9As shown, in addition to two LVDT housing mounting holes 27 for mounting the LVDT housing 18, the upper mounting cover 13 and the lower mounting cover 14 are also provided with two water-cooling inner channels. Each water-cooling inner channel has an inlet and an outlet, which can be connected to a water-cooling pipe head and circulated with cold water to control the operating temperature of the LVDT component and prevent overheating from affecting its performance. The water-cooling pipe port 25 of any mounting cover can be screwed into the water-cooling pipe head and inserted into the water-cooling pipe. The mounting cover plate is fixed to the mounting cover with screws, and the through hole in the middle of the cover plate allows the upper and lower pull heads to pass through. Both the mounting cover and its cover plate are provided with sealing ring grooves, which, after the sealing rings are installed, can achieve sealing between the mounting cover and the cover plate, between the mounting cover and the high-temperature furnace, and between the cover plate and the pull head. The mounting cover and the cover plate are both made of aluminum alloy; the pull head and the lead-out rod are both made of high-temperature ceramic.

[0060] Therefore, the sample deformation measurement system of the present invention includes two key devices: a deformation extraction measurement device and a video extensometer. The deformation extraction measurement device is installed on an in-situ high-temperature experimental furnace and includes several key components (taking a tensile test deformation extraction measurement device as an example): upper and lower pull heads, upper and lower lead-out rods, upper and lower mounting covers and cover plates, LVDT assembly (iron core and outer shell), iron core screws, and locking nuts. The upper and lower mounting covers serve as mounting seats for the LVDT outer shell, installed on the upper and lower end faces of the high-temperature furnace. Each mounting cover houses two sets of LVDT assemblies. The LVDT outer shell is installed in the mounting holes within the mounting covers and secured by screws inserted through screw holes on the side of the mounting covers. Grooves are cut on both the upper and lower end faces of the mounting covers for installing sealing rings. Sealing ring grooves are also designed on the cover plates to ensure a tight seal between the cover plate and the pull rods. The LVDT assembly consists of an iron core and an outer shell. The iron core is fixed to the lead-out rods by iron core screws, with the other end inserted into the LVDT outer shell. An induction coil is located inside the LVDT outer shell. The displacement of the iron core changes the magnetic field in the induction coil, causing a voltage change in the secondary coil, thus achieving displacement measurement.

[0061] Furthermore, the method by which the host computer determines the deformation of the test sample based on the displacement of the test sample and the displacement generated by the X-ray transmission thin-walled flange 5 is as follows:

[0062] During the stretching stage, the deformation is calculated as follows: the difference between the average displacement measured by the two upper LVDT components and the average displacement measured by the two lower LVDT components is obtained; the average displacement of the X-ray transmission thin-walled flange 5 measured by the four video extensometers 7 is obtained; and the difference between the difference and the average displacement of the X-ray transmission thin-walled flange 5 is taken as the deformation.

[0063] During the load holding phase, the deformation is the difference between the average displacement measured by the two upper LVDT components and the average displacement measured by the two lower LVDT components.

[0064] Furthermore, the method for obtaining the average displacement of the X-ray transmission thin-walled flange 5 measured by the four video extensometers 7 is as follows:

[0065] A mark is affixed vertically to the top and bottom of the X-ray transmission thin-walled flange 5, with a 90-degree interval between each mark, for a total of four sets. The camera position and focal length of each video extensometer 7 are adjusted so that each video extensometer 7 is aligned with one set of marks, ensuring that the marks are visible in the video. Each video extensometer 7 collects the distance change corresponding to each set of marks during the deformation of the sample under test. The average distance change between any two marks in the four sets of marks is taken as the average displacement of the X-ray transmission thin-walled flange 5.

[0066] Furthermore, the method by which the loading device 1 applies a tensile load to the test sample until the test sample breaks is as follows:

[0067] S1: The high-temperature furnace system heats the test sample 22 until the temperature reaches the set value, then the loading device 1 applies a tensile load to the test sample 22; the lead-out measuring device is used to measure the displacement generated during the deformation of the test sample 22; the video extensometer 7 is used to measure the displacement generated by the X-ray transmission thin-walled flange 5.

[0068] S2: After the loading device 1 applies a tensile load to the test sample 22 to the set value, it keeps the tensile load unchanged. At this time, in-situ CT imaging technology is used to perform X-ray scanning imaging of the deformation process of the test sample 22 from the X-ray transmission thin-walled flange 5.

[0069] S3: Repeat steps S1 and S2 until the test sample 22 breaks, and obtain the X-ray scanning image and deformation of the test sample during the entire tensile process.

[0070] Based on this, taking the tensile specimen deformation measurement method as an example, the present invention provides a specimen deformation measurement method for in-situ CT imaging ultra-high temperature mechanical loading experiments, including the following steps:

[0071] 1) Installation of the sample and the lower deformation measuring device:

[0072] Screw the core screw 20 fully into the screw hole at the end of the lower lead-out rod 23, then screw the LVDT core 19 into the tail of the screw 20 to ensure the core is fixed; slide the lower lead-out rod 23 onto the pull-down head 17 until the constricted inner surface of the lower lead-out rod 23 is engaged with the reducing surface of the pull-down head 17; install the sample 22 onto the pull-down head 17; connect and fix the lower mounting cover 14 and the lower cover plate 15 with screws; insert the LVDT housing 18 into the mounting hole 27 of the lower mounting cover 14, and screw the screws into the screw holes 26 on the side of the lower mounting cover 14. Until the LVDT housing 18 is fixed in place; insert the two LVDT cores 19 on the lower lead-out rod 23 into the LVDT housing 18 in the lower mounting cover 14, and let the pull-down head 17 pass through the through hole and out of the lower mounting cover plate 15; insert the lower lead-out rod and pull-down head and other components through the through hole on the lower end face of the furnace body 6 of the high temperature furnace, fix the lower mounting cover 14 to the lower end face of the furnace body 6 of the high temperature furnace with screws, and screw the locking nut 16 into the tail of the pull-down head to restrict the upward movement of the pull-down head 17, thus completing the installation of the lower structure of the device;

[0073] 2) Installation of the upper deformation lead-out measuring device:

[0074] Install and fix the upper pull head 11 to the sample 22; after installing the X-ray transmission thin-walled flange 5 on the lower furnace body 6 of the high-temperature furnace, install the upper furnace body 4 so that the upper pull head 11 passes through the through hole on the upper end face of the upper furnace body 4; insert the upper lead-out rod 21 into the furnace body from top to bottom through the through hole on the upper end face of the upper furnace body 4 until it is stuck at the variable diameter surface of the upper pull head 11 due to gravity; insert the two LVDT iron cores 19 on the upper lead-out rod 21 into the LVDT outer shell 18 in the upper mounting cover 13, and install the upper mounting cover 13 on the upper end face of the upper furnace body 4 of the high-temperature furnace with screws; connect the upper pull head 11 to the pull rod 10 with pins to complete the installation of the upper structure of the device;

[0075] 3) Install the water-cooling pipe head on the mounting cover and insert the water-cooling pipe, then turn on the cold water;

[0076] 4) Insert the signal connector into the signal connector socket on the mounting cover and begin data acquisition;

[0077] 5) Video extensometer setup:

[0078] To eliminate measurement errors in sample deformation caused by the deformation of the thin-walled flange during X-ray transmission, a video extensometer 7 was used to record the deformation of the thin-walled flange 5 during X-ray transmission, which was then used as a correction in the final sample deformation calculation. Four video extensometers 7 were set up around the assembled high-temperature in-situ loading system at 90-degree intervals, ensuring that the video extensometers 7 and the tripod did not obstruct the X-ray path. A black spot mark was affixed to the upper and lower vertical directions of the X-ray transmission thin-walled flange 5, with four sets affixed at 90-degree intervals. The position and focal length of the video extensometer 7 camera were adjusted so that each video extensometer was aligned with one set of marks, ensuring that the black spots were clearly visible in the video. The change in distance between the two marked points was then collected.

[0079] 6) The sample 22 is heated, and after the temperature stabilizes, the high-temperature tensile test is started. The loading device 1 applies a tensile load. During the tensile process, the upper and lower pull rods move upward through the lifting of the variable diameter surfaces of the upper pull head 11 and the lower pull head 17, respectively, and the displacement of the sample 22 near the gauge length section inside the high-temperature furnace is brought out of the furnace body. The displacement data is obtained by high-precision monitoring of the relative movement between the LVDT core 19 and the LVDT shell 18. At the same time, the video extensometer collects the deformation of the thin wall.

[0080] 7) After applying a certain load and holding it, perform X-ray scanning imaging on the sample; during the scanning imaging process, the high-temperature in-situ loading system and the upper and lower deformation lead-out measurement components will rotate together; at this time, the video extensometer stops collecting data;

[0081] 8) Repeat steps 6) and 7) until the specimen breaks; collect LVDT and video extensometer measurement data of the entire process and the tensile process.

[0082] 9) Processing displacement measurement data:

[0083] During the tensile process, the deformation of the gauge length of the specimen is calculated as the difference between the average displacement transmitted by the two upper LVDTs and the average displacement transmitted by the two lower LVDTs, minus the average distance change of the marker points collected by the four video extensometers; during the load holding process, the deformation of the gauge length of the specimen is calculated as the difference between the average displacement transmitted by the two upper LVDTs and the average displacement transmitted by the two lower LVDTs.

[0084] In summary, this invention provides a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments. It employs a high-temperature ceramic-assisted extraction design to extract the displacement of the sample near the gauge length and measure it using an LVDT (Linear Variable Differential Transformer). Simultaneously, to eliminate the influence of X-ray transmission through the thin wall of the high-temperature furnace on the measurement of sample deformation, a video extensometer is used to monitor the deformation of the thin wall in real time and ultimately correct the extracted deformation measurement. This achieves high-precision monitoring of sample deformation under ultra-high temperature conditions and meets the compatibility and real-time requirements of high-resolution in-situ CT imaging experiments. This invention provides an important tool for the study of the mechanical properties and microstructure mechanisms of high-temperature materials, filling a gap in existing technologies.

[0085] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A sample deformation measurement system for in-situ CT imaging of ultra-high temperature mechanical loading experiments, applied to a high-temperature furnace system based on in-situ CT imaging, characterized in that, The sample deformation measurement system comprises a host computer, a loading device (1), a leading measurement device and four video extensometers (7) arranged at an interval of 90 degrees around a high-temperature furnace system, and the video extensometers are opposite to an X-ray transmission thin-wall flange (5), and a sample to be tested is installed at a middle section of the leading measurement device; the high-temperature furnace system is used for providing different temperature environments for the sample to be tested (22), and is assembled by an upper furnace body (4), the X-ray transmission thin-wall flange (5) and a lower furnace body (6) in sequence; The leading measurement device penetrates into the high-temperature furnace system from the top of the upper furnace body (4) and penetrates out of the high-temperature furnace system from the bottom of the lower furnace body (6), so that the sample to be tested is located at a middle section of the high-temperature furnace system, and the sample to be tested (22) can be scanned by X-rays transmitted from the X-ray transmission thin-wall flange (5); The loading device (1) is used for connecting an upper end of the leading measurement device, so as to apply a tensile load to the sample to be tested (22) until the sample to be tested (22) is broken, and an in-situ CT imaging technology is used for scanning and imaging the deformation process of the sample to be tested (22) from the X-ray transmission thin-wall flange (5); meanwhile, the leading measurement device is used for measuring the displacement of the sample to be tested (22) during the deformation process; The four video extensometers (7) are used for measuring the displacement of the X-ray transmission thin-wall flange (5) during the deformation process of the sample to be tested (22) from four different directions; The host computer is used for three-dimensionally reconstructing the deformation process of the sample to be tested (22) according to the scanning and imaging results of the X-rays, and determining the deformation of the sample to be tested (22) according to the displacement of the sample to be tested (22) and the displacement of the X-ray transmission thin-wall flange (5); The leading measurement device comprises an upper deformation leading measurement assembly (3) installed in the upper furnace body (4) and a lower deformation leading measurement assembly (8) installed in the lower furnace body (6), and the sample to be tested is connected between the upper deformation leading measurement assembly (3) and the lower deformation leading measurement assembly (8); The up deformation leading-out measuring assembly (3) comprises an up pulling head (11), an up leading-out rod (21), an up mounting cover (13), two up LVDT assemblies, and two up core screws (20); the materials of the up pulling head (11) and the up leading-out rod (21) are high-temperature ceramics; the up mounting cover (13) is mounted on the upper end surface of the up furnace body (4); the two up LVDT assemblies are mounted in the mounting holes of the up mounting cover (13) and are fixed by the screws screwed into the side screw holes of the up mounting cover (13); the up leading-out rod (21) is a hollow cylindrical structure, and the upper end is provided with a first circular ring mounting lug extending outward; the two up core screws (20) are screwed into the screw holes in the first circular ring mounting lug, and the ends of the two up core screws (20) extending out of the screw holes are respectively connected with the two up LVDT assemblies in a threaded mode; meanwhile, the up leading-out rod (21) penetrates into the inside of the up furnace body (4) through the through hole in the upper end surface of the up furnace body (4), so that the up leading-out rod (21) is clamped at the variable-diameter surface of the up pulling head (11) sleeved on the inside of the up leading-out rod (21) due to the action of its own gravity, wherein the lower end of the up pulling head (11) also penetrates into the inside of the up furnace body (4) through the through hole in the upper end surface of the up furnace body (4) and is connected with the sample to be tested; the upper end of the up pulling head (11) penetrates out of the up mounting cover (13) from the middle of the two up LVDT assemblies, and then is connected with the loading device (1), so that the loading device (1) applies a tensile load to the sample to be tested through the up pulling head (11); the two up LVDT assemblies are used for measuring the displacement amount generated in the deformation process of the sample to be tested. The lower deformation leading measurement assembly (8) comprises a lower pull head (17), a lower leading rod (23), a lower mounting cover (14), two lower LVDT assemblies, and two lower core screws; the materials of the lower pull head (17) and the lower leading rod (23) are high-temperature ceramics; the lower mounting cover (14) is mounted on the lower end surface of the lower furnace body (6); the two lower LVDT assemblies are mounted in the mounting holes of the lower mounting cover (14) and are fixed by the screws screwed into the side screw holes of the lower mounting cover (14); the lower leading rod (23) has a hollow cylindrical structure, and the lower end is provided with a second circular ring mounting lug extending outward, and the upper end is provided with a third circular ring mounting lug extending inward; the two lower core screws are screwed into the screw holes in the second circular ring mounting lug, respectively, and the ends of the two lower core screws extending out of the screw holes are respectively connected with the two lower LVDT assemblies in a threaded manner; at the same time, the lower leading rod (23) penetrates into the inside of the lower furnace body (6) through the through hole in the lower end surface of the lower furnace body (6), so that the lower leading rod (23) is clamped at the variable-diameter surface of the lower pull head (17) sleeved in the inside of the lower leading rod (23) due to the action of its own gravity, wherein the upper end of the lower pull head (17) also penetrates into the inside of the lower furnace body (6) through the through hole in the lower end surface of the lower furnace body (6), and the upper end of the lower pull head (17) provides a tensile load for the lower pull head (17) through the connection with the sample to be tested; the lower end of the lower pull head (17) penetrates out of the lower mounting cover (14) from between the two lower LVDT assemblies; the lower end of the lower pull head (17) is provided with a locking nut, which can be clamped at the lower end surface of the lower mounting cover (14) to limit the upward movement of the lower pull head (17) during the tensile test; the two lower LVDT assemblies are used to measure the displacement generated in the deformation process of the sample to be tested.

2. The sample deformation measurement system for in-situ CT imaging of ultra-high temperature mechanical loading experiments of claim 1, wherein, Further comprising an upper cover plate (12) and a lower cover plate (15); The upper cover plate (12) is used for packaging the upper mounting cover (13), and the lower cover plate (15) is used for packaging the lower mounting cover (14).

3. The sample deformation measurement system for in-situ CT imaging of ultra-high temperature mechanical loading experiments of claim 1, wherein, The upper mounting cover (13) and the lower mounting cover (14) are further provided with water-cooling pipe heads; The water-cooling pipe heads are used for passing in cold water and are used for maintaining the working temperature of the upper LVDT assembly and the lower LVDT assembly in a set range, respectively.

4. The sample deformation measurement system for in-situ CT imaging of ultra-high temperature mechanical loading experiments of claim 1, wherein, Further comprising a stand column (2); The loading device (1) is mounted on the upper end surface of the upper furnace body (4) through the stand column (2).

5. The sample deformation measurement system for in-situ CT imaging of ultra-high temperature mechanical loading experiments of claim 1, wherein, The method for determining the deformation amount of the sample to be tested by the upper computer according to the displacement of the sample to be tested and the displacement of the X-ray transmission thin-wall flange (5) is: In the tensile stage, the calculation method of the deformation amount is: obtaining the difference between the average value of the displacement measured by the two upper LVDT assemblies and the average value of the displacement measured by the two lower LVDT assemblies; obtaining the average value of the displacement of the X-ray transmission thin-wall flange (5) measured by the four video extensometers (7); and taking the difference between the average value of the displacement of the X-ray transmission thin-wall flange (5) and the difference as the deformation amount; In the load holding stage, the deformation amount is the difference between the average value of the displacement measured by the two upper LVDT assemblies and the average value of the displacement measured by the two lower LVDT assemblies.

6. The sample deformation measurement system for in-situ CT imaging of ultra-high temperature mechanical loading experiments of claim 5, wherein, The method for obtaining the average value of the displacement of the X-ray transmission thin-wall flange (5) measured by the four video extensometers (7) is: Affix one mark to the top and one to the bottom of the vertical direction of the X-ray transmission thin-walled flange (5), with a 90-degree interval between each mark, for a total of four sets; Adjust the camera position and focal length of each video extensometer (7) so that each video extensometer (7) is aligned with a set of marks, ensuring that the marks are visible in the video; Each video extensometer (7) collects the distance change corresponding to each group of marks during the deformation of the sample under test; The average value of the distance change between two marks in the four sets of marks is taken as the average value of the displacement of the X-ray transmission thin-walled flange (5).

7. The specimen deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment as described in claim 1, wherein the loading device (1) applies a tensile load to the test specimen until the test specimen breaks as follows: S1: The test sample (22) is heated by the high temperature furnace system until the temperature reaches the set value. Then the loading device (1) applies a tensile load to the test sample (22). The lead-out measuring device is used to measure the displacement generated during the deformation of the test sample (22). The video extensometer (7) is used to measure the displacement generated by the X-ray transmission thin-walled flange (5). S2: After the loading device (1) applies a tensile load to the test sample (22) to the set value, the tensile load remains unchanged. At this time, the in-situ CT imaging technology is used to perform X-ray scanning imaging of the deformation process of the test sample (22) from the X-ray transmission thin-walled flange (5). S3: Repeat steps S1 and S2 until the test sample (22) breaks, and obtain the X-ray scanning image and deformation of the test sample during the entire tensile process.

8. The sample deformation measurement system for in-situ CT imaging of ultra-high temperature mechanical loading experiments of claim 7, wherein, It also includes a turntable (9); The turntable (9) is used to support the high-temperature furnace system and rotate the lead-out measuring device integrated with the high-temperature furnace system during the stage when the tensile load remains unchanged, so as to perform X-ray scanning imaging of the test sample from different angles.

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