Sample deformation measuring system for in-situ CT imaging ultrahigh-temperature mechanical loading experiment

Abstract

The invention provides a sample deformation measuring system for an in-situ CT imaging ultra-high-temperature mechanical loading experiment, which adopts a high-temperature ceramic material as an auxiliary extraction design, extracts the deformation of a gauge length section of a sample out of a high-temperature furnace and measures the deformation by using an LVDT (Linear Variable Differential Transformer); meanwhile, in order to eliminate the influence of the deformation of the X-ray transmission thin wall in the high-temperature furnace on the deformation measurement of the sample, a video extensometer is also adopted to monitor the deformation of the thin wall in real time, and the LVDT measurement result is corrected according to the data, so that the high-precision deformation measurement in the ultra-high-temperature environment is realized; the measurement system can be compatible with a high-resolution in-situ CT imaging experiment, meets the requirements of mechanical loading and microstructure imaging at the same time in a high-temperature environment, improves the real-time performance and precision of the in-situ experiment, provides a powerful tool for comprehensively researching the mechanical property and behavior of a material, and has a wide application prospect. Therefore, the comprehensive in-depth research requirements on material performance and behaviors are met, and the blank in the prior art is filled up.

Description

Technical Field

[0001] The invention belongs to the technical field of high temperature mechanical testing, and in particular relates to a sample deformation measurement system for an in-situ CT imaging ultra-high temperature mechanical loading experiment. Background Art

[0002] With the rapid development of aerospace, nuclear energy, automotive industry and other fields, materials that can work stably in ultra-high temperature environments have gradually become the focus of research. For example, materials such as ceramic-based composites, high-temperature resistant 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, it is particularly important to test and characterize the mechanical properties of materials under high temperature conditions. Traditional high-temperature mechanical properties testing methods, such as tensile, compression and bending experiments, usually obtain the basic mechanical parameters of materials by measuring the relationship between load and displacement. However, these methods mainly focus on macroscopic mechanical behavior, and it is difficult to deeply observe the changes in the microstructure inside the material, such as crack propagation, hole 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 because of its ability to perform three-dimensional non-destructive testing. Compared with traditional mechanical testing methods, in-situ CT imaging technology combined with mechanical loading experiments can observe the evolution of the internal microstructure of the material in real time during the loading process. This method provides dynamic, high-resolution three-dimensional images that help reveal microscopic mechanisms such as crack initiation and propagation, pore formation and merging, and interface damage.

[0004] In the in-situ CT imaging ultra-high temperature mechanical loading experiment, accurately monitoring the deformation of the sample is crucial for analyzing the high temperature mechanical behavior of the material. However, in an ultra-high temperature environment, the deformation monitoring of the sample faces a series of challenges. First, some traditional displacement measurement methods (such as external LVDT sensors) will produce large errors when measuring outside a high-temperature furnace due to the interference of the temperature gradient in the high-temperature furnace and the thermal deformation of the device. On the other hand, in a small high-temperature furnace that cooperates with high-resolution in-situ CT, the operating space is narrow, and the ultra-high temperature environment may cause complex thermal interference to the sensor and the deformation measurement device, which may cause the measurement device to fail to work normally due to material performance degradation or electromagnetic radiation interference, significantly reducing the measurement accuracy and stability. In addition, in-situ CT imaging requires that the sample and the loading device can be scanned in three dimensions without obstruction within the field of view of the X-ray beam, which puts forward strict requirements on the structure of the deformation measurement device: not only must the structure be compact and the effect of X-ray absorption or scattering be minimized, but also complex mechanical components must be avoided to block the imaging field of view of the CT. Finally, in the in-situ CT imaging process, the microstructural changes inside the material need to be characterized by high-resolution three-dimensional reconstruction. If the measurement error of the sample deformation is large, it will directly affect the imaging quality and the accuracy of subsequent analysis. Therefore, the deformation measurement device is required to have high measurement accuracy.

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

[0006] In order to solve the above technical problems, the present invention provides a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments, which can achieve accurate measurement of sample deformation in a small-sized closed high-temperature environment by optimizing sensor layout, introducing high-temperature resistant materials and adopting LVDT measurement technology.

[0007] A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment, applied to a high temperature furnace system based on in-situ CT imaging, the sample deformation measurement system comprises a host computer, a loading device 1, an extraction measurement device and four video extensometers 7 arranged around the high temperature furnace system at 90 degrees intervals, and the video extensometers are directly opposite to the X-ray transmission thin-walled flange 5, and the sample to be tested is installed in the middle part 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 in sequence 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 penetrates into the high-temperature furnace system from the top of the upper furnace body 4 and passes 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 in the middle of the high-temperature furnace system, and the sample to be tested 22 can be scanned by the X-rays transmitted from the X-ray transmission thin-wall flange 5;

[0009] The loading device 1 is used to connect the upper end of the lead-out measuring device, so as to apply a tensile load to the test sample 22 until the test sample 22 breaks, and use the 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 X-ray transmission thin-wall 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 on the deformation process of the test sample 22 according to the result of X-ray scanning imaging, and determine the deformation amount of the test sample 22 according to the displacement amount of the test sample 22 and the displacement amount caused by the X-ray transmission of the thin-walled flange 5.

[0012] Further, the lead-out measurement device comprises an upper deformation lead-out measurement component 3 installed in the upper furnace body 4 and a lower deformation lead-out measurement component 8 installed in the lower furnace body 6, and the sample to be tested is connected between the upper deformation lead-out measurement component 3 and the lower deformation lead-out measurement component 8;

[0013] The upper deformation lead-out measurement 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 mounted on the upper end surface of the upper furnace body 4; the two upper LVDT assemblies are mounted in the mounting holes of the upper mounting cover 13, and are supported and fixed by screws pushed into the screw holes on the side surfaces of the upper mounting cover 13; the upper lead-out rod 21 is a hollow cylindrical structure, and a first circular ring mounting ear extending outward is provided at the upper end; the two upper core screws 20 are respectively screwed into the screw holes on the first circular ring mounting ears, and one end of the two upper core screws 20 extending out of the screw holes is respectively screwed with the threads of 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 into the interior of the upper furnace body 4, so that the upper lead-out rod 21 is stuck at the reducing surface of the upper pull head 11 sleeved inside the upper lead-out rod 21 due to its own gravity, wherein 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 into the interior of the upper furnace body 4, and is connected with the sample to be tested; the upper end of the upper pull head 11 passes through the upper mounting cover 13 from the middle of the two upper LVDT assemblies, and then is connected to the loading device 1, and the loading device 1 applies a tensile load to the sample to be tested through the upper pull head 11; the two upper LVDT assemblies are used to measure the displacement generated during the deformation of the sample to be tested;

[0014] The lower deformation lead-out measurement assembly 8 includes a lower pull head 17, a lower lead-out rod 23, a lower mounting cover 14, two lower LVDT assemblies, and two lower iron core screws; wherein 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 supported and fixed by screws pushed into the screw holes on the side surfaces of the lower mounting cover 14; the lower lead-out rod 23 is a hollow cylindrical structure, and a second circular ring mounting ear extending outward is provided at the lower end, and a third circular ring mounting ear extending inward is provided at the upper end; the two lower iron core screws are respectively screwed into the screw holes on the second circular ring mounting ears, and one end of the two lower iron core screws extending out of the screw holes are respectively threadedly connected to the two lower LVDT assemblies; at the same time, the lower lead-out rod 23 passes through the lower furnace The through hole on the lower end face of the body 6 penetrates into the interior of the lower furnace body 6, so that the lower lead-out rod 23 is stuck on the reducing surface of the lower pull head 17 sleeved inside the lower lead-out rod 23 through the third circular ring mounting ear due to its own gravity, wherein the upper end of the lower pull head 17 also penetrates into the interior of the lower furnace body 6 through the through hole on the lower end face 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 by connecting the test sample; the lower end of the lower pull head 17 passes through the lower mounting cover 14 from the middle of the two lower LVDT assemblies; a locking nut is installed on the lower end of the lower pull head 17, which can be stuck on the lower end face 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 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 encapsulate the upper mounting cover 13 , and the lower cover plate 15 is used to encapsulate the lower mounting cover 14 .

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

[0018] The water-cooling pipe head is used to pass cold water, and is used to control the working 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 surface of the upper furnace body 4 through the column 2.

[0021] Furthermore, the host computer determines the deformation of the sample to be tested according to the displacement of the sample to be tested and the displacement generated by the X-ray penetrating thin-wall flange 5 in the following manner:

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

[0023] In the load-holding stage, the deformation is the difference between the average displacement measured by the two upper LVDT assemblies and the average displacement measured by the two lower LVDT assemblies.

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

[0025] A mark is attached to the upper and lower sides of the X-ray transmission thin-wall flange 5 in the vertical direction, and four sets are attached at intervals of 90 degrees;

[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 process of the test sample;

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

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

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

[0031] S2: After the loading device 1 applies a tensile load to the test sample 22 to a set value, the tensile load is kept unchanged. At this time, an 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-wall 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 stretching 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 rotate the extraction measurement device integrated with the high temperature furnace system when the tensile load remains unchanged, so as to perform X-ray scanning imaging of the test sample at different viewing angles.

[0035] Beneficial effects:

[0036] The present invention provides a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments, which adopts high temperature ceramic materials as an auxiliary lead-out design, leads the deformation of the sample gauge section to the outside of the high temperature furnace and uses LVDT for measurement; at the same time, in order to eliminate the influence of the deformation of the thin wall transmitted by X-rays in the high temperature furnace on the sample deformation measurement, the present invention also adopts a video extensometer to monitor the thin wall deformation in real time, and corrects the LVDT measurement result according to its data, thereby realizing high-precision deformation measurement in an ultra-high temperature environment; the measurement system of the present invention is compatible with high-resolution in-situ CT imaging experiments, meets the needs of simultaneous mechanical loading and microstructure imaging in a high temperature environment, and improves the real-time performance and accuracy of the in-situ experiments; the system of the present invention is suitable for a variety of high-temperature in-situ experiments such as tension, compression, shearing, bending, indentation, etc., and provides a powerful tool for comprehensively studying the mechanical properties and behaviors of materials, so as to meet the needs of comprehensive and in-depth research on the properties and behaviors of materials, and fills the gap in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic front view 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 A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment provided by the present invention;

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

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

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

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

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

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

[0045] Fig. 9 An isometric diagram of an embodiment of an 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-wall 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, 13-upper mounting cover, 14-lower mounting cover, 15-lower cover, 16-locking nut, 17-lower pull head, 18-LVDT housing, 19-LVDT core, 20-core screw, 21-upper lead-out rod, 22-sample to be tested, 23-lower lead-out rod, 24-signal connector socket, 25-water cooling pipe mouth, 26-screw hole, 27-LVDT housing mounting hole. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0048] like Figure 1 and Figure 2 As shown, a sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment 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 around the high temperature furnace system at 90 degrees, and the video extensometers are facing the X-ray transmission thin-walled flange 5. The sample to be tested is installed in the middle part 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 by an upper furnace body 4, an X-ray transmission thin-walled flange 5, and a lower furnace body 6 in sequence;

[0049] like Figure 3 and Figure 4 As shown, the lead-out measuring device penetrates into the high-temperature furnace system from the top of the upper furnace body 4 and passes 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 in the middle section of the high-temperature furnace system, and the sample to be tested 22 can be scanned by the X-rays transmitted from the X-ray transmission thin-wall flange 5;

[0050] The loading device 1 is used to connect the upper end of the lead-out measuring device, so as to apply a tensile load to the test sample 22 until the test sample 22 breaks, and use the 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 X-ray transmission thin-wall 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 according to the result of the X-ray scanning imaging, and determine the deformation amount of the test sample 22 according to 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 surface of the upper furnace body 4 through the column 2;

[0054] The turntable 9 is used to support the high temperature furnace system and rotate the extraction measurement device integrated with the high temperature furnace system when the tensile load remains unchanged, so as to perform X-ray scanning imaging of the test sample at different viewing angles.

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

[0056] like Figure 5 to Figure 7 As shown, the upper deformation lead-out measurement 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 mounted on the upper end surface of the upper furnace body 4; the two upper LVDT assemblies are mounted in the mounting holes of the upper mounting cover 13, and are supported and fixed by screws pushed into the screw holes on the side of the upper mounting cover 13; the upper cover plate 12 is used to encapsulate the upper mounting cover 13; the upper lead-out rod 21 is a hollow cylindrical structure, and a first circular ring mounting ear extending outward is provided at the upper end; as shown Figure 8 As shown, two upper iron core screws 20 are respectively screwed into the screw holes on the first circular ring mounting ears, and one end of the two upper iron core screws 20 extending out of the screw holes are respectively threadedly connected with 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 to penetrate into the interior of the upper furnace body 4, so that the upper lead-out rod 21 is stuck at the reducing surface of the upper pull head 11 sleeved inside the upper lead-out rod 21 due to its own gravity, wherein 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 to penetrate into the interior of the upper furnace body 4 and is connected with a sample to be tested; the upper end of the upper pull head 11 passes through the upper mounting cover 13 from the middle of the two upper LVDT assemblies, and then is connected to the loading device 1, and the loading device 1 applies a tensile load to the sample to be tested through the upper pull head 11; the two upper LVDT assemblies are used to measure the displacement generated during the deformation process of the sample to be tested;

[0057] The lower deformation lead-out measurement assembly 8 includes a lower pull head 17, a lower lead-out rod 23, a lower mounting cover 14, two lower LVDT assemblies, and two lower iron core screws; wherein 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 supported and fixed by screws inserted into the screw holes on the side surfaces of the lower mounting cover 14; the lower cover plate 15 is used to encapsulate the lower mounting cover 14; the lower lead-out rod 23 is a hollow cylindrical structure, and a second circular ring mounting ear extending outward is provided at the lower end, and a third circular ring mounting ear extending inward is provided at the upper end; the two lower iron core screws are respectively screwed into the screw holes on the second circular ring mounting ears, and one end of the two lower iron core screws extending out of the screw holes are respectively threadedly connected to the two lower LVDT assemblies; at the same time, ... The output rod 23 penetrates into the lower furnace body 6 through the through hole on the lower end face of the lower furnace body 6, so that the lower lead-out rod 23 is stuck on the reducing surface of the lower pull head 17 sleeved inside the lower lead-out rod 23 through the third circular ring mounting ear due to its own gravity, wherein the upper end of the lower pull head 17 also penetrates into the lower furnace body 6 through the through hole on the lower end face 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 by connecting the test sample; the lower end of the lower pull head 17 passes through the lower mounting cover 14 from the middle of the two lower LVDT assemblies; a locking nut is installed at the lower end of the lower pull head 17, which can be stuck on the lower end face 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 during the deformation of the test sample.

[0058] That is to say, the upper lead-out rod 21 and the lower lead-out rod 23 are respectively sleeved on the outer side 11 of the upper pull head and the outer side 17 of the lower pull head; the lower end surface of the upper lead-out rod 21 is stuck at the diameter-changing surface of the upper pull head 11 due to gravity; the inner surface of the shrinkage of the lower lead-out rod 23 is stuck at the diameter-changing 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 for telescopic movement; the LVDT assembly can transmit displacement data through a signal line inserted into the signal connector socket 24 of the mounting cover.

[0059] It should be noted that if Fig. 9As shown, in addition to the 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 of which has a water inlet and a water outlet, which can be connected to a water-cooling pipe head and pass cold water to control the working temperature of the LVDT assembly to prevent overheating from affecting its performance. Among them, the water-cooling pipe port 25 of any mounting cover can be screwed into the water-cooling pipe head through a thread and inserted into the water-cooling pipe; the mounting cover cover plate is connected and fixed to the mounting cover by screws, and the through hole in the middle of the cover plate is used for the upper and lower pull heads to pass through; the mounting cover and its cover plate are both provided with sealing ring grooves, and after the sealing ring is installed, the sealing between the mounting cover-cover plate, the mounting cover-high-temperature furnace, and the cover plate-pull head can be achieved. The materials of the mounting cover and the cover plate are both made of aluminum alloy; the materials of the pull head and the lead-out rod are both made of high-temperature ceramics.

[0060] It can be seen that the sample deformation measurement system of the present invention includes two key devices: a deformation extraction measurement device and a video extensometer. The deformation lead-out measuring device is installed on the in-situ high-temperature experimental furnace, including multiple key components (taking the tensile test deformation lead-out measuring device as an example): upper and lower pull heads, upper and lower lead-out rods, upper and lower mounting covers and cover plates, LVDT components (iron core and shell), core screws, and locking nuts; among them, the upper and lower mounting covers serve as mounting seats for the LVDT shell and are installed on the upper and lower end surfaces of the high-temperature furnace, and each mounting cover is installed with two sets of LVDT components; the LVDT shell is installed in the mounting hole in the mounting cover and is fixed by screws pushed into the screw holes on the side of the mounting cover; grooves are provided on the upper and lower end surfaces of the mounting cover for installing sealing rings; a sealing ring groove is also designed on the cover plate of the mounting cover to ensure the sealing between the cover plate and the pull rod; the LVDT assembly consists of an iron core and a shell; the iron core is fixed to the lead-out rod by the iron core screws, and the other end is inserted into the LVDT shell; there is an induction coil in the LVDT shell, and the displacement of the iron core will change the magnetic field in the induction coil, resulting in a voltage change in the secondary coil in the induction coil, thereby realizing the measurement of displacement.

[0061] Furthermore, the host computer determines the deformation of the sample to be tested according to the displacement of the sample to be tested and the displacement generated by the X-ray penetrating thin-wall flange 5 in the following manner:

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

[0063] In the load-holding stage, the deformation is the difference between the average displacement measured by the two upper LVDT assemblies and the average displacement measured by the two lower LVDT assemblies.

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

[0065] A mark is affixed in the vertical direction of the X-ray transmission thin-walled flange 5, with four groups of marks affixed at 90 degrees intervals; the camera position and focal length of each video extensometer 7 are adjusted so that each video extensometer 7 is aligned with a group of marks to ensure 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 test sample; the average value of the distance change between the two marks of the four groups of marks is taken as the average displacement of the X-ray transmission thin-walled flange 5.

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

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

[0068] S2: After the loading device 1 applies a tensile load to the test sample 22 to a set value, the tensile load is kept unchanged. At this time, an 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-wall 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 stretching 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 experiment, comprising the following steps:

[0071] 1) Installation of the specimen and lower deformation measurement device:

[0072] Screw the core screw 20 completely into the screw hole at the end of the lower lead-out rod 23, and then screw the LVDT core 19 into the tail of the screw 20 to ensure that the core is fixed; insert the lower lead-out rod 23 into the lower pull head 17 until the inner surface of the shrinkage of the lower lead-out rod 23 is stuck at the diameter reduction surface of the lower pull head 17; install the sample 22 on the lower pull 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 it into the screw hole 26 on the side of the lower mounting cover 14 with a screw. Until it presses against the LVDT housing 18 to fix it; 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 make the lower pull head 17 pass through the through hole to pass through the lower mounting cover cover 15; insert the lower lead-out rod and the lower pull head and other components through the through hole on the lower end surface of the lower furnace body 6 of the high-temperature furnace, fix the lower mounting cover 14 to the lower end surface of the lower furnace body 6 of the high-temperature furnace by screws, screw the locking nut 16 into the tail of the lower pull head to limit the upward movement of the lower pull head 17, and complete the installation of the lower structure of the device;

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

[0074] Install and fix the upper pull head 11 and 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 diameter-changing surface of the upper pull head 11 due to gravity; insert the two LVDT cores 19 on the upper lead-out rod 21 into the LVDT housing 18 in the upper mounting cover 13, and mount the upper mounting cover 13 on the upper end face of the upper furnace body 4 of the high-temperature furnace by screws; connect the upper pull head 11 with the pull rod 10 by pins to complete the installation of the upper structure of the device;

[0075] 3) Install the water cooling pipe head on the installation cover and insert the water cooling pipe, and let in cold water;

[0076] 4) Insert the signal connector into the signal connector socket of the mounting cover and start collecting data;

[0077] 5) Video extensometer installation:

[0078] In order to eliminate the measurement error of the specimen deformation caused by the deformation of the transmitted thin wall, a video extensometer 7 is used to record the deformation of the X-ray transmission thin-wall flange 5, so as to make a correction item in the final specimen deformation calculation; four video extensometers 7 are set up around the assembled high-temperature in-situ loading system at an interval of 90 degrees to ensure that the video extensometer 7 and the tripod do not block the X-ray path; a black spot mark is affixed to the upper and lower sides of the X-ray transmission thin-wall flange 5 in the vertical direction, and four groups are affixed at an interval of 90 degrees; the camera position and focal length of the video extensometer 7 are adjusted, and each video extensometer is aligned with a group of marks to ensure that the black spots are clearly visible in the video; and the distance change between the two marking points is collected;

[0079] 6) Heat up the specimen 22. After the temperature stabilizes, start the high-temperature tensile test, and the loading device 1 applies a tensile load. During the tensile process, the upper and lower lead-out rods move upward respectively by the lifting of the variable-diameter surfaces of the upper pull head 11 and the lower pull head 17, leading out the displacement of the specimen 22 near the gauge section in the high-temperature furnace outside the furnace body. The displacement data is obtained by accurately monitoring the relative movement between the LVDT iron core 19 and the LVDT housing 18. At the same time, the video extensometer collects the deformation of the transmissive thin wall.

[0080] 7) Hold the load after applying a certain load and perform X-ray scanning imaging on the specimen. During the scanning imaging process, the high-temperature in-situ loading system and the upper and lower two 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 fractures. Collect the LVDT measurement data throughout the process and the video extensometer measurement data during the tensile process.

[0082] 9) Process the displacement measurement data:

[0083] During the tensile process, the deformation of the gauge section of the specimen is calculated as the difference between the average value of the displacements transmitted by the upper two sets of LVDTs and the average value of the displacements transmitted by the lower two sets of LVDTs, minus the average value of the distance changes of the marked points collected by the four video extensometers. During the load-holding process, the deformation of the gauge section of the specimen is calculated as the difference between the average value of the displacements transmitted by the upper two sets of LVDTs and the average value of the displacements transmitted by the lower two sets of LVDTs.

[0084] In summary, the present invention provides a specimen deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiments. It adopts a high-temperature ceramic-assisted lead-out design to lead out the displacement of the specimen near the gauge section and measures it with an LVDT (Linear Variable Differential Transformer). At the same time, in order to eliminate the influence of the deformation of the X-ray transmissive thin wall in the high-temperature furnace on the measurement of the specimen deformation, a video extensometer is used to monitor the deformation of the X-ray transmissive thin wall in real time and finally correct the lead-out measurement deformation, realizing high-precision monitoring of the specimen deformation in an ultra-high temperature environment and meeting the compatibility and real-time requirements of high-resolution in-situ CT imaging experiments. The present invention provides an important tool for the study of the mechanical properties and micro-mechanisms of high-temperature materials, filling the gap in the existing technology.

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

Claims

1. A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment, 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), an extraction measurement device, and four video extensometers (7) arranged around a high-temperature furnace system at intervals of 90 degrees, and the video extensometers are directly opposite to the X-ray transmission thin-wall flange (5), and the sample to be tested is installed in the middle part 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 in sequence from an upper furnace body (4), an X-ray transmission thin-wall flange (5), and a lower furnace body (6); The lead-out measuring device penetrates into the high-temperature furnace system from the top of the upper furnace body (4) and passes 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 in the middle of the high-temperature furnace system, and the sample to be tested (22) can be scanned by the X-rays transmitted from the X-ray transmission thin-wall flange (5); 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-wall 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); The four video extensometers (7) measure the displacement of the X-ray-transmitting thin-wall flange (5) during the deformation of the test sample (22) from four different directions respectively; The host computer is used to perform three-dimensional reconstruction of the deformation process of the test sample (22) according to the result of X-ray scanning imaging, and determine the deformation amount of the test sample (22) according to the displacement amount of the test sample (22) and the displacement amount caused by the X-ray transmission of the thin-walled flange (5).

2. A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment according to claim 1, characterized in that: The lead-out measurement device comprises an upper deformation lead-out measurement component (3) installed in an upper furnace body (4) and a lower deformation lead-out measurement component (8) installed in a lower furnace body (6), and the sample to be tested is connected between the upper deformation lead-out measurement component (3) and the lower deformation lead-out measurement component (8); The upper deformation lead-out measurement assembly (3) comprises 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 mounted on the upper end surface of the upper furnace body (4); the two upper LVDT assemblies are mounted in the mounting holes of the upper mounting cover (13), and are supported and fixed by screws pushed into the screw holes on the side surfaces of the upper mounting cover (13); the upper lead-out rod (21) is a hollow cylindrical structure, and a first circular ring mounting ear extending outward is provided at the upper end; the two upper core screws (20) are respectively screwed into the screw holes on the first circular ring mounting ears, and one end of the two upper core screws (20) extending out of the screw holes is respectively 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), so that the upper lead-out rod (21) is stuck at the diameter-changing surface of the upper pull head (11) sleeved inside the upper lead-out rod (21) due to its own gravity, wherein 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 a sample to be tested; 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), and the loading device (1) applies a tensile load to the sample to be tested through the upper pull head (11); the two upper LVDT assemblies are used to measure the displacement generated during the deformation of the sample to be tested; The lower deformation lead-out measurement assembly (8) comprises a lower pull head (17), a lower lead-out rod (23), a lower mounting cover (14), two lower LVDT assemblies, and two lower iron core screws; wherein 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 supported and fixed by screws pushed into the screw holes on the side surfaces of the lower mounting cover (14); the lower lead-out rod (23) is a hollow cylindrical structure, and a second circular ring mounting ear extending outward is provided at the lower end, and a third circular ring mounting ear extending inward is provided at the upper end; the two lower iron core screws are respectively screwed into the screw holes on the second circular ring mounting ears, and one end of the two lower iron core screws extending out of the screw holes are respectively threadedly connected to the two lower LVDT assemblies; at the same time, the lower lead-out rod (23) is screwed into the lower end of the lower furnace body (6) The through hole on the end face penetrates into the interior of the lower furnace body (6), so that the lower lead-out rod (23) is clamped on the reducing surface of the lower pull head (17) sleeved inside the lower lead-out rod (23) through the third circular ring mounting ear due to its own gravity, wherein the upper end of the lower pull head (17) also penetrates into the interior of the lower furnace body (6) through the through hole on the lower end face 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) by connecting to the test sample; the lower end of the lower pull head (17) passes through the lower mounting cover (14) between the two lower LVDT assemblies; a locking nut is installed on the lower end of the lower pull head (17), which can be clamped on the lower end face 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 during the deformation of the test sample.

3. A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment according to claim 2, characterized in that: It also includes an upper cover plate (12) and a lower cover plate (15); The upper cover plate (12) is used to encapsulate the upper mounting cover (13), and the lower cover plate (15) is used to encapsulate the lower mounting cover (14).

4. A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment according to claim 2, characterized in that: The upper mounting cover (13) and the lower mounting cover (14) are also provided with water cooling pipe heads; The water-cooling pipe head is used to pass cold water, and is used to control the working temperature of the upper LVDT component and the lower LVDT component to maintain within a set range.

5. The sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment according to claim 1, characterized in that: Also includes a column (2); The loading device (1) is installed on the upper end surface of the upper furnace body (4) via a column (2).

6. A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment according to claim 2, characterized in that: The method in which the host computer determines the deformation amount of the sample to be tested according to the displacement amount of the sample to be tested and the displacement amount generated by the X-ray penetrating thin-wall flange (5) is as follows: In the stretching stage, the deformation is calculated by: obtaining the difference between the average displacement values ​​measured by the two upper LVDT components and the average displacement values ​​measured by the two lower LVDT components; obtaining the average displacement value of the X-ray transmission thin-wall flange (5) measured by four video extensometers (7); and taking the difference and the difference between the average displacement value of the X-ray transmission thin-wall flange (5) as the deformation; In the load-holding stage, the deformation is the difference between the average displacement measured by the two upper LVDT assemblies and the average displacement measured by the two lower LVDT assemblies.

7. A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment according to claim 6, characterized in that: The method for obtaining the average displacement of the X-ray transmission thin-wall flange (5) measured by four video extensometers (7) is as follows: A mark is affixed on the upper and lower sides of the X-ray transparent thin-wall flange (5) in the vertical direction, and four sets of marks are affixed at intervals of 90 degrees; 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 process of the test sample; The average value of the distance changes between two marks of the four groups of marks is taken as the average value of the displacement of the X-ray transmission thin-wall flange (5).

8. The sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment according to claim 1, wherein the method in which the loading device (1) applies a tensile load to the sample to be tested until the sample to be tested breaks is: S1: The test sample (22) is heated by a high temperature furnace system until the temperature reaches a set value, and then a loading device (1) applies a tensile load to the test sample (22); an extraction measuring device is used to measure the displacement generated during the deformation of the test sample (22); and a video extensometer (7) is used to measure the displacement generated by the X-ray transmission thin-wall flange (5); S2: After the loading device (1) applies a tensile load to the test sample (22) to a set value, the tensile load is kept unchanged, and at this time, an 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-wall 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 stretching process.

9. A sample deformation measurement system for in-situ CT imaging ultra-high temperature mechanical loading experiment according to claim 8, characterized in that: Also includes a turntable (9); The turntable (9) is used to support the high-temperature furnace system and rotate the extraction measurement device integrated with the high-temperature furnace system in a stage where the tensile load remains unchanged, so as to perform X-ray scanning imaging of the test sample at different viewing angles.

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