Method and device for testing mechanical failure behavior of multilayer structure pipe of nuclear reactor

Abstract

The invention discloses a mechanical failure behavior testing method and device for a multilayer structure pipe of a nuclear reactor, and belongs to the field of pipe in-situ testing. The method comprises the following steps: controlling a loading module to load a multilayer structure pipe, and obtaining a force value curve of a load borne by the multilayer structure pipe in a loading process; wherein the multi-layer structure pipe is a pipe with more than two layers of structures; controlling a CT scanning module to carry out CT scanning on the multi-layer structure pipe under the condition that feature points appear on the force value curve every time until the change rate of the load reaches a first preset change rate threshold value, and obtaining a first CT image corresponding to each feature point; wherein the characteristic point is that the change rate of the load reaches a second preset change rate threshold value; and based on the first CT image corresponding to each feature point, determining a damage coordinate and a damage form of the multi-layer structure pipe under each load. The invention provides an in-situ testing method capable of analyzing the mechanical failure behavior of the multi-layer structure pipe.

Description

Technical Field

[0001] This application belongs to the field of in-situ testing of pipe materials, specifically relating to a method and apparatus for testing the mechanical failure behavior of multi-layered pipe materials for nuclear reactors. Background Technology

[0002] In pressurized water reactor nuclear power plants, the current cladding uses multi-layered tubing, such as SiC / SiC composite tubing, which mainly includes two-layer and three-layer structural designs. The two-layer structure consists of an inner ceramic matrix composite (CMC) layer plus an outer CVD-SiC ceramic layer. The three-layer structure includes an inner SiC layer plus a middle CMC layer plus an outer CVD-SiC ceramic layer, and an inner metal layer plus a middle CMC layer plus an outer CVD-SiC ceramic layer. The multi-layered structural design primarily ensures the airtightness, corrosion resistance, and mechanical strength and toughness of the cladding tubing during service.

[0003] To analyze the mechanical failure behavior of multilayer pipes, in-situ testing is required. However, traditional in-situ testing techniques lack the capability to analyze the mechanical failure behavior of multilayer pipes. For example, in-situ scanning electron microscopy (SEM) can only scan the surface of multilayer pipes to analyze and characterize the mechanical failure behavior of the surface structure.

[0004] Therefore, there is an urgent need for an in-situ testing method that can analyze the mechanical failure behavior of multi-layered pipe structures. Summary of the Invention

[0005] The purpose of this application is to provide a method and apparatus for testing the mechanical failure behavior of multi-layered pipes in nuclear reactors, which can provide an in-situ testing method for analyzing the mechanical failure behavior of multi-layered pipes.

[0006] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, embodiments of this application provide a method for testing the mechanical failure behavior of multilayer structural tubing in a nuclear reactor, applied to a testing system including a CT scanner; the CT scanner includes a loading module and a CT scanning module; the loading module is used to fix a fixture and load the multilayer structural tubing clamped in the fixture; the method includes: The loading module is controlled to load the multi-layer structure pipe and the force curve of the load borne by the multi-layer structure pipe during the loading process is obtained; wherein, the multi-layer structure pipe is a pipe with two or more layers. The CT scanning module is controlled to perform CT scans on the multi-layer structure pipe each time a feature point appears on the force curve, until the rate of change of the load reaches a first preset rate of change threshold, and a first CT image corresponding to each feature point is obtained; wherein, the feature point is when the rate of change of the load reaches a second preset rate of change threshold, and the second preset rate of change threshold is less than the first preset rate of change threshold. Based on the first CT image corresponding to each of the aforementioned feature points, the damage coordinates and damage modes of the multi-layer structure pipe under each of the aforementioned loads are determined.

[0007] Secondly, embodiments of this application provide a mechanical failure behavior testing device for multi-layered tubing of a nuclear reactor. The mechanical failure behavior testing device for multi-layered tubing of a nuclear reactor includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the steps of the method described in the first aspect.

[0008] Thirdly, embodiments of this application provide a computer-readable storage medium on which a program or instructions are stored, which, when executed by a processor, implement the steps of the method described in the first aspect.

[0009] Fourthly, embodiments of this application also provide a computer program product, including a computer program that, when executed by a processor, implements the steps of the method described in the first aspect.

[0010] In this embodiment, a multi-layered pipe is loaded using a CT scanner. A first CT image is obtained each time a characteristic point appears on the force curve of the load on the multi-layered pipe. The damage coordinates and damage mode of the multi-layered pipe under each load are determined using the first CT image, thus completing the in-situ test for analyzing the mechanical failure behavior of the multi-layered pipe. In other words, this embodiment provides an in-situ testing method capable of analyzing the mechanical failure behavior of multi-layered pipes. Attached Figure Description

[0011] Figure 1 These are exploded views of tooling provided in some embodiments of this application; Figure 2 This is a cross-sectional view of the tooling provided in some embodiments of this application after clamping multi-layered pipes; Figure 3 These are perspective views of the tooling provided in some embodiments of this application after it has been installed on the loading platform; Figure 4 This is a flowchart illustrating a method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor, provided in some embodiments of this application. Figure 5 This is an internal structural diagram of a mechanical failure behavior testing device for multi-layered tubular structures of nuclear reactors provided in some embodiments of this application.

[0012] Figure label: 1. Multi-layered pipe structure; 2. Lower base; 3. Elastic insert; 4. Upper compression seat; 41. Oil guide groove; 51. Loading component; 52. Scanning turntable; 6. Centering module; 7. Base pin; 8. Soft ring. Detailed Implementation

[0013] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0014] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0015] The mechanical failure behavior testing method for multi-layered tubing in nuclear reactors provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0016] In one exemplary embodiment, this application relates to a testing system including a computed tomography (CT) device, which includes a loading module and a CT scanning module; the loading module is used to fix a fixture and load a multi-layered pipe 1 clamped in the fixture.

[0017] The CT scanning module can be a flat panel detector.

[0018] For example, the testing system also includes a testing device for the mechanical failure behavior of multi-layered tubing in a nuclear reactor, capable of 3D reconstruction. This testing device for the mechanical failure behavior of the multi-layered tubing in a nuclear reactor may include, but is not limited to, a computer, a cloud server, or a host computer for a CT scanner.

[0019] For example, see Figure 1 , Figure 1 This is an exploded view of a fixture for clamping multi-layered pipe 1. The fixture includes a lower base 2, an elastic insert 3, and an upper compression seat 4. One side of the lower base 2 has a protrusion forming a first support column, which supports the multi-layered pipe 1. The elastic insert 3 is inserted into the multi-layered pipe 1, with its bottom surface in close contact with the end face of the first support column. One side of the upper compression seat 4 has a protrusion forming a second support column, with the end face of the second support column in close contact with the end face of the elastic insert 3.

[0020] Understandable, see [link / reference] Figure 2 The loading module loads the multi-layer pipe 1 by loading the upper compression seat 4 of the tooling, and finally transmits the force to the multi-layer pipe 1 through the upper compression seat 4 and the elastic insert 3. This tooling is used to conduct a plugging test on the multi-layer pipe 1, thereby enabling testing under conditions close to the actual application environment of the multi-layer pipe 1, i.e., in-situ testing of the multi-layer pipe 1. The loading component 51 can be a hydraulic drive mechanism, etc.

[0021] It should be noted that, in order to avoid the upper compression seat 4 generating axial force on the multi-layer structure pipe 1, the second support column should avoid directly exerting force on the multi-layer structure pipe 1. In one embodiment, the second support column is cylindrical, and its diameter is less than or equal to the inner diameter of the multi-layer structure pipe 1. The length of the multi-layer structure pipe 1 is 3 cm, the length of the first support column is 1 cm, the length of the elastic insert 3 is 1 cm, and the length of the second support column is greater than 1 cm.

[0022] It should be noted that the cladding of the multi-layer structure pipe 1 is subjected to internal compression during nuclear reactor operation. Therefore, in this embodiment, the elastic insert 3 of the tooling is loaded, and the elastic insert 3 deforms after being subjected to force, thereby compressing the inner wall of the multi-layer structure pipe 1, thus simulating the internal pressure stress state of the multi-layer structure pipe 1.

[0023] In one embodiment, to reduce the impact of the tooling on X-ray attenuation, the lower base 2 and the upper compression seat 4 can be made of low-attenuation materials, such as tungsten alloy and titanium alloy. That is, the lower base 2 can be a tungsten alloy lower base 2 or a titanium alloy lower base 2, and the upper compression seat 4 can be a tungsten alloy upper compression seat 4 or a titanium alloy upper compression seat 4, etc.

[0024] In one embodiment, see Figure 3 The fixture also includes at least three reference pins 7, each of which is inserted into the lower base 2 of the fixture and evenly distributed on the same circumference. The center of the circumference is a point on the axis of the multi-layer structure pipe 1. The reference pins 7 are used to construct an actual three-dimensional coordinate system and determine the first transformation coefficient between pixel coordinates and actual three-dimensional coordinates, thereby realizing the transformation between pixel coordinates in CT data (such as two-dimensional CT images, three-dimensional volume data, etc.) and actual three-dimensional coordinates. For example, if there are three reference pins 7, the average coordinates of the three reference pins 7 are the origin of the actual three-dimensional coordinate system, that is, the coordinates of the center of the circle. The axis of the multi-layer structure pipe 1, the line connecting the center of the circle to any one of the reference pins 7, and the circumferential angle are three-dimensional. The actual three-dimensional coordinates are determined by the actual dimensions of the multi-layer structure pipe 1, that is, the distance between two actual three-dimensional coordinates is the actual spatial distance.

[0025] Furthermore, each reference pin 7 is provided with a soft ring 8, which is used to fix the multi-layer structure pipe 1 and avoid the multi-layer structure pipe 1 from being eccentric during loading, which would lead to inaccurate test results.

[0026] In one embodiment, the second support column is provided with an oil guide groove 41. The oil guide groove 41 is used to inject pressure-resistant oil between the multilayer structure pipe 1 and the elastic insert 3. The pressure-resistant oil is used to lubricate the contact surface between the multilayer structure pipe 1 and the elastic insert 3. That is, the oil guide groove 41 is used to guide the pressure-resistant oil to form an oil film around the elastic insert 3. This oil film can play a role in lubrication and uniform load distribution, thereby making the pipe wall of the multilayer structure pipe 1 more uniformly stressed and reducing the friction between the elastic insert 3 and the pipe wall. This makes the test environment more consistent with the actual application environment of the multilayer structure pipe 1 and improves the accuracy of the test. Here, pressure-resistant oil refers to lubricating oil that can withstand high pressure.

[0027] Furthermore, the elastic insert 3 can be made of a material with a Shore hardness range of 40A-90A, such as a polyurethane elastic insert 3. The elastic insert 3 maintains a certain gap with the inner wall of the multilayer pipe 1, for example, a gap of 0.2mm. This gap facilitates the injection of pressure-resistant oil and the formation of a pressure-resistant oil film, thereby reducing the shear stress introduced by friction between the elastic insert 3 and the inner wall of the multilayer pipe 1, further improving the accuracy of the test.

[0028] In one embodiment, the fixture further includes a centering module 6, which can be driven by a ball screw, linear motor, or other drive mechanism to move the multi-layered pipe 1 along two mutually perpendicular directions. The centering module 6 allows adjustment of the axis position of the multi-layered pipe 1 to achieve centering, thereby improving the coaxiality between the loading force, the elastic insert 3, and the multi-layered pipe 1 during loading. This reduces the risk of damage to the multi-layered pipe 1 caused by eccentricity and further improves the accuracy of the test.

[0029] Based on the aforementioned CT equipment, in an exemplary embodiment, this application proposes a method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor, which is applied to the aforementioned testing system.

[0030] It should be noted that before implementing this method, the CT equipment needs to be prepared, such as fixing the fixture onto the scanning turntable 52 of the loading module. If the CT equipment has just been turned on, a power-on self-test and automatic calibration of the equipment are also required. This includes calibrating the X-ray source (e.g., tube voltage fluctuation ≤ ±1kV, tube current fluctuation ≤ ±2mA) and the detector (e.g., grayscale response linearity error ≤ 3%).

[0031] In response to receiving configuration parameters input by the user, or by directly using default parameters, various parameters of the CT scanning module are configured. For example, the preset tube voltage is 130kV, tube current is 70mA, scan slice thickness is 0.5μm, reconstruction matrix is ​​2048×2048, exposure time is 0.5s / frame, scanning turntable rotation step size is 0.1° / frame, and a cumulative acquisition of ≥1440 valid images is achieved.

[0032] After the CT equipment has completed its preparation, the mechanical failure behavior testing device for the multi-layered tubing of the nuclear reactor in the testing system can begin executing the method. (Refer to...) Figure 4 The method includes steps 402-406. Wherein: Step 402: Control the loading module to load the multi-layer structure pipe 1 and obtain the force curve of the load borne by the multi-layer structure pipe 1 during the loading process; wherein, the multi-layer structure pipe 1 is a pipe with two or more layers.

[0033] During the loading process, the loading rate can be controlled, for example, to 1 mm / min; and the load can be acquired in real time by a force sensor installed in the loading component 51. It can be understood that the force curve is obtained through this load, specifically, it can be a curve showing the relationship between load and loading time.

[0034] Step 404: Control the CT scanning module to perform CT scanning on the multi-layer structure pipe 1 each time a feature point appears on the force curve, until the rate of change of the load reaches a first preset rate of change threshold, and obtain a first CT image corresponding to each feature point; wherein, the feature point is when the rate of change of the load reaches a second preset rate of change threshold, and the second preset rate of change threshold is less than the first preset rate of change threshold.

[0035] It is understandable that the rate of change can be the change of the load obtained in this acquisition compared to the load in the previous acquisition. When a characteristic point appears, it indicates that the multi-layer structure pipe 1 has been damaged, such as crack initiation, crack propagation, or complete failure.

[0036] Therefore, when feature points are present, the first CT image obtained by CT scanning of the multi-layered pipe 1 must contain information about the damage.

[0037] It should be noted that the real-time load data reflects the reaction force of the pressure borne by the inner wall of the multi-layer pipe 1 in real time. Before damage occurs to the multi-layer pipe 1, the load increases over time. When damage occurs to the multi-layer pipe 1, the reaction force will decrease rapidly in a short period of time due to the damage, i.e., the rate of change of the load reaches the first preset rate of change threshold. After the multi-layer pipe 1 completely fails, the reaction force will return to zero or be close to zero in a short period of time.

[0038] The first preset rate of change threshold and the second preset rate of change threshold can be set based on experience, and this embodiment does not impose any restrictions.

[0039] Step 406: Based on the first CT image corresponding to each of the feature points, determine the damage coordinates and damage form of the multi-layer structure pipe 1 under each of the loads.

[0040] It is understandable that the first CT image carries damage information, such as the pixel coordinates and number of cracks. Both the first CT image and the load have a correspondence with feature points; therefore, the relationship between damage coordinates and load can be established through this correspondence. For example, if feature point 'a' appears on the force curve, a CT scan is performed on the multi-layered pipe 1 to obtain the first CT image corresponding to feature point 'a'. Then, the load corresponding to feature point 'a' can be directly determined from the force curve; thus, the damage coordinates in the first CT image under that load can be obtained.

[0041] It can be understood that the damage coordinates and damage forms obtained under various loads from the experiment constitute a "time-series data stream" that precisely corresponds to the macroscopic mechanical behavior of the multilayer structure pipe 1 and its internal microstructural dynamic evolution. The damage coordinates represent the coordinates of the location where damage occurs; damage forms include point, line, and planar cracks, as well as through-damage. It can be understood that by combining the damage coordinates and damage forms under various loads, the location of crack initiation can be clearly identified, such as crack initiation in the inner layer; and the crack propagation path after crack initiation can be analyzed, such as a new crack appearing in the intermediate layer after crack initiation in the inner layer. The propagation path refers to the layer where the crack corresponding to each characteristic point in the time sequence is located. It can be understood that through crack initiation and propagation paths, the structural failure relationship of each layer of the multilayer structure pipe 1 can be established, and this structural failure relationship can be used to guide the process optimization and service safety analysis of the multilayer structure pipe 1.

[0042] This embodiment uses a CT scanner to load the multi-layered pipe 1. A first CT image is obtained each time a characteristic point appears on the force curve of the load on the multi-layered pipe 1. The damage coordinates and damage mode of the multi-layered pipe 1 under each load are determined using the first CT image, thus completing an in-situ test to analyze the mechanical failure behavior of the multi-layered pipe 1. In other words, this embodiment provides an in-situ testing method capable of analyzing the mechanical failure behavior of a multi-layered pipe 1.

[0043] In one embodiment, controlling the CT scanning module to perform CT scans on the multi-layered pipe 1 each time a feature point appears on the force curve, until the rate of change of the load reaches a first preset rate of change threshold, and obtaining a first CT image corresponding to each feature point, includes: controlling the loading module to stop loading and controlling the CT scanning module to perform CT scans on the multi-layered pipe 1 when a feature point appears on the force curve; controlling the loading module to continue loading the multi-layered pipe 1 after the CT scanning module completes the CT scan; and returning to the step of controlling the loading module to stop loading and controlling the CT scanning module to perform CT scans on the multi-layered pipe 1 when a feature point appears again on the force curve, until the rate of change of the load reaches the first preset rate of change threshold, and obtaining a first CT image corresponding to each feature point.

[0044] It is understandable that, in addition to controlling the loading module to stop loading, the loading rate of the loading component 51 in the loading module can also be reduced, so that the CT scanning module can complete the CT scan of the multi-layer structure pipe 1 before the next characteristic point appears on the force value curve.

[0045] In one embodiment, determining the damage coordinates of the multi-layer pipe 1 under each load based on the first CT image corresponding to each feature point includes: reconstructing a three-dimensional model corresponding to each feature point based on the first CT image; determining the damage area from the target three-dimensional model and determining the damage coordinates of the damage area; wherein the target three-dimensional model is a three-dimensional model corresponding to any one of the feature points; after determining the damage coordinates corresponding to all three-dimensional models, obtaining the damage coordinates and damage form of the multi-layer pipe 1 under the loads corresponding to each three-dimensional model.

[0046] In this context, the damaged area generally refers to the region where the crack is located. During the crack initiation stage, this damaged area is most likely a point; while in the subsequent crack propagation stage, it is generally a line or a surface. Therefore, when the damaged area is a point, the damage coordinates can be the coordinates of that point; while when the damaged area is a line or a surface, the damage coordinates can be a set of coordinates that characterize the damaged area. This set of coordinates can be a set of coordinates on the outline of the damaged area, or a set of coordinates for the internal regions of the damaged area.

[0047] Furthermore, based on the first CT image, a three-dimensional model corresponding to each feature point is reconstructed, including: performing image enhancement processing on the first CT image; wherein the image enhancement processing includes at least one of the following: noise reduction, grayscale adjustment, and edge enhancement; performing hierarchical segmentation on the enhanced first CT image to obtain a first CT image with hierarchical attribute labels; and reconstructing a three-dimensional model corresponding to each feature point based on the first CT image with hierarchical attribute labels.

[0048] Noise reduction refers to filtering CT images to eliminate grayscale interference caused by X-ray noise and detector noise generated during CT scanning.

[0049] Grayscale adjustment involves adjusting the grayscale value of the CT image to improve its contrast, i.e., increasing the grayscale difference between the layers of the multi-layered pipe 1 in the CT image. For example, adjusting the grayscale value of the CT image to 180.

[0050] Edge enhancement refers to edge sharpening.

[0051] It is understandable that the purpose of image enhancement processing is to strengthen the boundary contours of each layer of the multi-layered pipe 1 in the CT image, so as to accurately divide the multi-layered pipe 1 in the CT image.

[0052] It should be noted that after the 3D model is reconstructed, based on the hierarchical segmentation of the CT image, the 3D model of each layer can be displayed separately.

[0053] Among them, the hierarchical attribute label can be carried by pixels, that is, the hierarchical attribute label corresponds to the pixel coordinates, such as pixel coordinates (2,2) for the inner layer and (100,100) for the middle layer.

[0054] Further, determining the damage coordinates of the damaged area includes: obtaining the pixel coordinates of the damaged area; based on the pixel coordinates, calling a coordinate transformation model to generate actual three-dimensional coordinates; and using the actual three-dimensional coordinates as the damage coordinates of the damaged area.

[0055] It should be noted that the coordinate transformation model is a mathematical model constructed from mathematical formulas relating pixel coordinates and actual 3D coordinates. For example, x = u × k, where x is the x-coordinate in actual 3D coordinates, u is the pixel coordinate corresponding to the x-coordinate, and k is the first transformation coefficient.

[0056] It can be understood that pixel coordinates represent the nth pixel relative to the origin, meaning the difference between pixel coordinates is the number of pixels between the corresponding pixels. Furthermore, the scale is the same for any coordinate axis, while the actual 3D coordinates represent the physical distance relative to the origin, such as 10mm. Therefore, the first conversion factor is the same for the conversion between actual 3D coordinates and pixel coordinates on any coordinate axis. For example, if the pixel coordinates are (u, v, w) and the actual 3D coordinates are (x, y, z), then x = u × k, y = v × k, and z = w × k.

[0057] The actual three-dimensional coordinates can be the distances between each coordinate axis and the origin, or they can include circumferential angles. That is, the actual three-dimensional coordinates of the multi-layer structure pipe 1 are represented by axial, radial and circumferential coordinates.

[0058] Furthermore, for cases where the actual three-dimensional coordinates include circumferential angles, the second conversion coefficient corresponding to the circumferential angle is different from the first conversion coefficient mentioned above. The second conversion coefficient is the conversion coefficient between the circumferential angle and the circumferential span. The second conversion coefficient is determined based on at least three reference pins 7 set on the tooling, wherein each of the reference pins 7 is inserted into the lower base 2 of the tooling and is evenly distributed on the same circumference, and the center of the circumference is a point on the axis of the multi-layer structure pipe 1.

[0059] In this embodiment, before the loading module is controlled to load the multi-layer structure pipe 1, the method further includes: determining a first conversion coefficient and a second conversion coefficient. Specifically, firstly, the CT scanning module is controlled to perform a CT scan on the reference pin 7 and the multi-layer structure pipe 1 to obtain a second CT image; from the second CT image, the number of first pixels corresponding to the first radius of the circumference and the number of second pixels corresponding to the circumferential span of two adjacent reference pins 7 are determined; based on the number of first pixels and the actual radius of the circumference, a first conversion coefficient is determined; based on the circumferential angle between two adjacent reference pins 7, the number of second pixels, and the actual outer diameter of the multi-layer structure pipe 1, a second conversion coefficient is determined; wherein, the first conversion coefficient and the second conversion coefficient are used to determine the coordinate transformation model.

[0060] Among them, circumferential span refers to the pixels on a circular arc, such as the pixels on the circular arc corresponding to two adjacent reference pins 7 in the second CT image.

[0061] It should be noted that each reference pin 7 is etched with a crosshair, and the intersection of these crosshairs is the center point of reference pin 7. Therefore, the pixel representing reference pin 7 on the second CT image can be this center point.

[0062] For the second conversion coefficient, since the arc length of the arc corresponding to different radii is different at the same angle, the conversion coefficient calculated through the circumference of the reference pin 7 (i.e., the ratio of the circumferential angle to the number of second pixels) cannot be directly used as the second conversion coefficient. It still needs to be converted by the ratio between half of the actual outer diameter of the multi-layer structure pipe 1 and the actual radius of the circumference of the reference pin 7.

[0063] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0064] In one exemplary embodiment, a testing device for the mechanical failure behavior of multilayer tubing in a nuclear reactor is provided. This testing device can be a terminal, and its internal structural diagram can be as follows: Figure 5As shown, the mechanical failure behavior testing device for the multilayer tubing of the nuclear reactor includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computational and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides the environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When executed by a processor, this computer program implements a method for testing the mechanical failure behavior of multilayer tubing in a nuclear reactor. The display unit of this testing device is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the outer casing of the testing device, or an external keyboard, touchpad, or mouse.

[0065] Those skilled in the art will understand that Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the mechanical failure behavior testing device for multilayer structural tubing of nuclear reactors to which the present application is applied. A specific mechanical failure behavior testing device for multilayer structural tubing of nuclear reactors may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0066] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0068] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for testing the mechanical failure behavior of multi-layered tubular structures in nuclear reactors, characterized in that, The method is applied to a testing system, which includes a CT scanner; the CT scanner includes a loading module and a CT scanning module; the loading module is used to fix a fixture and load a multi-layered pipe clamped in the fixture; the method includes: The loading module is controlled to load the multi-layer structure pipe and the force curve of the load borne by the multi-layer structure pipe during the loading process is obtained; wherein, the multi-layer structure pipe is a pipe with two or more layers. The CT scanning module is controlled to perform CT scans on the multi-layer structure pipe each time a feature point appears on the force curve, until the rate of change of the load reaches a first preset rate of change threshold, and a first CT image corresponding to each feature point is obtained; wherein, the feature point is when the rate of change of the load reaches a second preset rate of change threshold, and the second preset rate of change threshold is less than the first preset rate of change threshold. Based on the first CT image corresponding to each of the aforementioned feature points, the damage coordinates and damage modes of the multi-layer structure pipe under each of the aforementioned loads are determined.

2. The method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor according to claim 1, characterized in that, The CT scanning module is controlled to perform CT scans on the multi-layered pipe structure each time a feature point appears on the force curve, until the rate of change of the load reaches a first preset rate of change threshold, thereby obtaining a first CT image corresponding to each feature point, including: When a characteristic point appears on the force curve, the loading module is controlled to stop loading, and the CT scanning module is controlled to perform a CT scan on the multi-layer structure pipe. After the CT scanning module completes the CT scan, the loading module is controlled to continue loading the multi-layer structure pipe. If the characteristic point reappears on the force curve, return to the step of controlling the loading module to stop loading and controlling the CT scanning module to perform a CT scan on the multi-layer structure pipe; until the rate of change of the load reaches the first preset rate of change threshold, and obtain the first CT image corresponding to each characteristic point.

3. The method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor according to claim 1, characterized in that, The step of determining the damage coordinates and damage mode of the multi-layered pipe under each load based on the first CT image corresponding to each feature point includes: Based on the first CT image, a three-dimensional model corresponding to each feature point is reconstructed. The damaged area is determined from the target 3D model, and the damage coordinates of the damaged area are determined; wherein, the target 3D model is the 3D model corresponding to any one of the feature points; After determining the damage coordinates corresponding to all three-dimensional models, the damage coordinates and damage modes of the multi-layer structure pipe under the loads corresponding to each of the three-dimensional models are obtained.

4. The method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor according to claim 3, characterized in that, The process of reconstructing a three-dimensional model corresponding to each feature point based on the first CT image includes: The first CT image is subjected to image enhancement processing; wherein the image enhancement processing includes at least one of the following: noise reduction, grayscale adjustment, and edge enhancement; The enhanced first CT image is segmented into layers to obtain a first CT image with layer attribute labels. Based on the first CT image with hierarchical attribute labels, a three-dimensional model corresponding to each feature point is reconstructed.

5. The method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor according to claim 3, characterized in that, Determining the damage coordinates of the damaged area includes: Obtain the pixel coordinates of the damaged area; Based on the pixel coordinates, the coordinate transformation model is invoked to generate the actual 3D coordinates; The actual three-dimensional coordinates are used as the damage coordinates of the damaged area.

6. The method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor according to claim 5, characterized in that, The tooling is provided with at least three reference pins, each of which is inserted into the lower base of the tooling and is evenly distributed on the same circumference, the center of which is a point on the axis of the multi-layer structure pipe; before the loading module is controlled to load the multi-layer structure pipe, the method further includes: The CT scanning module is controlled to perform CT scans on the reference pin and the multi-layered pipe to obtain a second CT image; From the second CT image, determine the number of first pixels corresponding to the first radius of the circumference, and the number of second pixels corresponding to the circumferential span of two adjacent reference pins; The first conversion coefficient is determined based on the first number of pixels and the actual radius of the circumference; The second conversion coefficient is determined based on the circumferential angle between two adjacent reference pins, the number of the second pixels, and the actual outer diameter of the multi-layer structure tube. The first transformation coefficient and the second transformation coefficient are used to determine the coordinate transformation model.

7. The method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor according to claim 6, characterized in that, The tooling also includes: an elastic insert and an upper compression seat; The lower base has a protrusion on one side to form a first support column, which is used to support the multi-layer structure pipe. The elastic insert is inserted into the interior of the multi-layer structure tube, and its bottom surface is in close contact with the end face of the first support column. The upper compression seat has a protrusion on one side to form a second support column, and the end face of the second support column is in close contact with the end face of the elastic insert.

8. The method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor according to claim 7, characterized in that, The tooling also includes an alignment module; The centering module is used to adjust the position of the axis of the multi-layer structure pipe to complete the centering.

9. The method for testing the mechanical failure behavior of multi-layered tubing in a nuclear reactor according to claim 7, characterized in that, The second support column is provided with an oil guide groove; The oil guide groove is used to inject pressure-resistant oil between the multi-layer structure pipe and the elastic insert, and the pressure-resistant oil is used to lubricate the contact surface between the multi-layer structure pipe and the elastic insert.

10. A testing device for the mechanical failure behavior of multi-layered tubular structures in nuclear reactors, characterized in that, The apparatus includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein the program or instructions, when executed by the processor, implement the steps of the method as described in any one of claims 1 to 9.

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