Shielding-free imaging in-situ tensile test device and three-dimensional imaging method thereof

Abstract

The invention relates to a non-shielding imaging in-situ tensile test device. A first fixing plate and a second fixing plate are elastically connected through a net-shaped bearing structure; a first motor is fixedly mounted on the first fixing plate, and a second motor is fixedly mounted on the second fixing plate; in the net-shaped bearing structure, the two ends of the sample are connected with the first motor and the second motor respectively, so that stretching of the sample is achieved through movement of the first motor and the second motor; the net-shaped bearing structure allows X-rays to pass through in an unshielded mode so that the sample can be imaged. The invention further relates to a three-dimensional imaging method of the unshielded imaging in-situ tensile test device. When a sample tensile test is carried out, X-rays can pass through the sample without shielding, so that high-quality synchrotron radiation X-ray CT imaging is realized, continuous three-dimensional imaging can be carried out while the sample is stressed, and the shielding problem in the imaging process can be avoided without increasing the intensity of a light source.

Description

Technical Field

[0001] The present invention relates to in-situ mechanical loading, and more particularly to an unobstructed imaging in-situ tensile test device and a three-dimensional imaging method thereof. Background Art

[0002] In the field of materials science and related research areas, in-depth study of the microstructure evolution and property change mechanisms of materials under mechanical loading conditions is of extremely important significance for the development of high-performance materials and the optimization of material applications. Synchrotron radiation X-ray CT imaging technology, with its unique advantages, has become a powerful tool for achieving these research goals.

[0003] The synchrotron radiation X-ray CT imaging in the prior art relies on a fixed incident light source. By rotating the sample 180°, images are continuously acquired during the rotation process, and finally, the three-dimensional characterization of the sample is completed using image processing algorithms. During the imaging process, mechanical loading operations such as tensile or compressive loading on the sample can be further performed to achieve the in-situ mechanical characterization of the materials. In the design of the in-situ device, to meet the loading requirements, the tensile loading motor is usually arranged at the upper end or the lower end to achieve the loading function, that is, designed as fixed clamping at the upper end and tensile by the lower motor; or fixed clamping at the lower end and tensile by the upper motor.

[0004] To achieve mechanical loading during synchrotron radiation X-ray CT imaging, a 360° annular (i.e., cylindrical) bearing column structure is usually adopted. This structure can ensure the effective load bearing and conduction of the force when the sample rotates 180°. To reduce the blocking and attenuation of X-rays, the bearing column is usually made of plastics with weak X-ray absorption ability such as acrylic. However, to meet the design requirements of the mechanical load range, the bearing column needs to have a large thickness, which is feasible under the condition of strong incident light (for example, the light flux is 10 12 -10 13 at this level).

[0005] Synchrotron radiation nano three-dimensional imaging technology can achieve three-dimensional imaging at the nano scale and is applicable to samples with a size of about 10 μm. Compared with micron-scale imaging, the X-ray light intensity required for this technology is significantly weaker. In the optical path, materials with a large thickness are likely to cause the X-rays to be blocked and attenuated. Research shows that when the material thickness exceeds 50 μm, the optical path may be completely blocked. Especially in CT imaging based on weak incident light (for example, the light flux is 10 10 at this level), it is extremely challenging to achieve continuous image acquisition of 180° under in-situ mechanical loading conditions, which directly hinders the realization of in-situ mechanical three-dimensional reconstruction during nano three-dimensional imaging.

[0006] The ring-shaped bearing structures in the prior art can seriously affect the imaging effect under low-light conditions because these structures can attenuate X-rays. Under the condition of weak incident light with a light intensity magnitude of 10 10 in the case of weak incident light, the traditional fully-occluding CT imaging method requires a strong light source with a light flux of 10 12 -10 13 , and the bearing columns need to be made of plastic materials with relatively weak X-ray absorption ability, such as acrylic, to reduce light attenuation during imaging. If materials with stronger X-ray absorption ability, such as steel, are used as bearing columns, the light attenuation will be very serious, resulting in difficult imaging. This indicates that it is difficult to balance the imaging quality while achieving mechanical loading in the prior art, especially under low-light conditions. Summary of the Invention

[0007] Aiming at the problem that it is difficult to achieve continuous image acquisition under weak incident light conditions mentioned in the prior art, the present invention provides an unoccluded imaging in-situ tensile test device and its three-dimensional imaging method.

[0008] An unoccluded imaging in-situ tensile test device according to the present invention includes a first fixing plate, a second fixing plate, a mesh-shaped bearing structure, a first motor, and a second motor. Among them, the first fixing plate and the second fixing plate are elastically connected through the mesh-shaped bearing structure; the first motor is fixedly installed on the first fixing plate, and the second motor is fixedly installed on the second fixing plate; inside the mesh-shaped bearing structure, both ends of the sample are respectively connected to the first motor and the second motor to realize the stretching of the sample through the movement of the first motor and the second motor; the mesh-shaped bearing structure allows X-rays to pass through without occlusion so as to image the sample.

[0009] In a preferred embodiment, the mesh-shaped bearing structure includes a plurality of stainless steel bearing columns.

[0010] In a preferred embodiment, four bearing columns are welded together with equal diameter and gradually rotated by 90°. ,

[0011] In a preferred embodiment, the spiral directions of the first bearing column and the fourth bearing column are opposite, and their starting points and ending points overlap and are connected by welding; the second bearing column and the third bearing column are also arranged with opposite spiral directions, and their starting points and ending points overlap and are connected by welding; these bearing columns are also connected by welding at the intermediate intersection points to form a symmetrical overall structure.

[0012] In a preferred embodiment, each bearing column is designed with an internal cavity to insert a resistance wire or pour liquid nitrogen.

[0013] In a preferred embodiment, the first motor and the second motor are respectively welded below the first fixing plate and above the second fixing plate through four-side reinforcing ribs and are located inside the mesh bearing structure.

[0014] In a preferred embodiment, the first motor and the second motor are respectively piezoelectric coaxial displacement motors to precisely control the displacement and stretching of the sample.

[0015] In a preferred embodiment, the unobstructed imaging in-situ stretching test device further includes an integrated control box, which is fixedly installed on the second fixing plate and is connected to the first motor and the second motor through wires or cables to achieve precise control of the motors.

[0016] The three-dimensional imaging method of the unobstructed imaging in-situ stretching test device according to the present invention includes the following steps: S1, driving the sample to be loaded and stretched by the first motor and / or the second motor, at this time the X-ray irradiates the sample unobstructedly; S2, realizing continuous image acquisition within the first angle range; S3, the first motor and the second motor move simultaneously to make the sample shift upward by a length of half a spring pitch, and at the same time the whole device moves downward by a length of half a spring pitch to keep the position of the sample unchanged; S4, realizing continuous image acquisition within the second angle range, the second angle range is complementary to the first angle range and jointly covers an imaging angle of 0-180°; S5, through image registration processing, integrating the 0-180° continuous image acquisition of the same area to generate a complete three-dimensional image of the sample.

[0017] In a preferred embodiment, the first angle range is 0-90°, and the second angle range is 90°-180°.

[0018] According to the unobstructed imaging in-situ stretching test device of the present invention, when performing a sample stretching test, the X-ray can pass through the sample unobstructedly, thereby realizing high-quality synchrotron radiation X-ray CT imaging, enabling continuous three-dimensional imaging of the sample while being stressed, and avoiding the occlusion problem during the imaging process without increasing the light source intensity. This not only improves the imaging quality but also makes it possible to perform continuous image acquisition of the sample under weak incident light conditions. The structure is simple, the manufacturing cost is low, and it can also be extended to other three-dimensional imaging experiments. Description of the Drawings

[0019] Figure 1 is a schematic diagram of the overall structure of an unobstructed imaging in-situ stretching test device according to a preferred embodiment of the present invention.

[0020] Figure 2 is Figure 1 the front view of

[0021] Figure 3It is a schematic structural diagram of a mesh bearing structure according to another preferred embodiment of the present invention.

[0022] Figure 4 It is a schematic structural diagram of a mesh bearing structure according to still another preferred embodiment of the present invention.

[0023] Figure 5 and Figure 6 is Figure 1 a schematic diagram of the optical path during image acquisition of Detailed Embodiments

[0024] The preferred embodiments of the present invention will be given and described in detail below in conjunction with the accompanying drawings.

[0025] As Figure 1 shown, a non-occlusive imaging in-situ tensile test device according to a preferred embodiment of the present invention includes a first fixing plate 1, a second fixing plate 2, a mesh bearing structure 3, a sample 4, a first motor 5 and a second motor 6. The mesh bearing structure 3 plays an elastic connection role between the first fixing plate 1 and the second fixing plate 2, supports and connects the two fixing plates and allows a certain degree of mobility therebetween. The first motor 5 is fixedly installed on the first fixing plate 1, and the second motor 6 is fixedly installed on the second fixing plate 2. Inside the mesh bearing structure 3, both ends of the sample 4 are respectively connected to the first motor 5 and the second motor 6, and the sample 4 is stretched by the movement of the first motor 5 and the second motor 6.

[0026] In the present invention, a synchrotron radiation light source (not shown in the figure) is fixedly arranged outside the mesh bearing structure 3. The special design of the mesh bearing structure 3 allows X-rays to be introduced without occlusion and to be incident on the sample 4 in a parallel manner. After the first motor 5 and the second motor 6 are loaded to a predetermined displacement amount, they will perform a load-holding operation to keep the sample 4 stable under the stressed state, so as to facilitate CT imaging of the sample 4. Compared with the occlusion problem that may be caused by the 360° annular bearing structure in the prior art, the present invention takes advantage of the mesh bearing structure 3 and can avoid the influence of occlusion on the imaging quality without increasing the light source intensity. Therefore, the present invention can achieve continuous image acquisition of the sample 4 under weak incident light conditions, which is difficult to achieve in the prior art.

[0027] Compared with the occlusion problem that may be caused by the 360° annular bearing structure in the prior art, the present invention takes advantage of the mesh bearing structure 3 and can avoid the influence of occlusion on the imaging quality without increasing the light source intensity. Therefore, the present invention can achieve continuous image acquisition of the sample 4 under weak incident light conditions, which is difficult to achieve in the prior art.

[0028] In this embodiment, the first fixing plate 1 is a first disc structure located at the top of the device, and the second fixing plate 2 is a second disc structure located at the bottom of the device. The two disc structures are arranged in parallel.

[0029] In this embodiment, the distance between the first fixing plate 1 and the second fixing plate 2 determines the height of the entire device. The function of the mesh bearing structure 3 is equivalent to that of a number of high-strength springs, and these springs are arranged between the first fixing plate 1 and the second fixing plate 2 to provide the necessary elastic support and stability.

[0030] In this embodiment, the second fixing plate 2 is fixed to the turntable by magnetic attraction, so that the entire device can rotate to adapt to different test angles and imaging requirements. Specifically, as Figure 2 shown, the second fixing plate 2 has three magnetic attraction positioning beads 2-1, 2-2, and 2-3. The entire device is fixed to the air-bearing turntable through the second fixing plate 2 and its magnetic attraction positioning beads 2-1, 2-2, and 2-3.

[0031] In this embodiment, the first fixing plate 1 and the second fixing plate 2 are made of 7xxx series aluminum alloy material, and the specific series number is determined according to the actual material. This material selection aims to ensure the overall rigidity of the equipment while effectively reducing the overall mass and ensuring stability and reliability during the mechanical loading process.

[0032] In this embodiment, the mesh bearing structure 3 is made of stainless steel material. This material is convenient for fixing by magnetic attraction, and due to its relatively large density, the device can obtain higher translational stability. Compared with the acrylic material used in the prior art, the strength of stainless steel is significantly higher. The strength of the mesh bearing structure 3 in the present invention is greater than 1000 MPa, while the strength of traditional acrylic is generally not more than 100 MPa. Therefore, the present invention can use less material to achieve the required strength, thereby reducing the shielding of X-rays and improving the imaging quality.

[0033] In this embodiment, the mesh bearing structure 3 is composed of four bearing columns 3-1, 3-2, 3-3, and 3-4. They are welded step by step with equal diameter and spacing by rotating 90°, and the spacing just accommodates the observation area of the sample 4. As Figure 1 shown, the spiral directions of the first bearing column 3-1 and the fourth bearing column 3-4 are opposite, and their starting points and ending points overlap with each other on the front side and are firmly connected by welding. Similarly, the second bearing column 3-2 and the third bearing column 3-3 are also arranged with opposite spiral directions, and their starting points and ending points overlap on the rear side and are connected by welding. In addition, these bearing columns are also connected by welding at the intersection points in the middle to form a strong left-right symmetric overall structure. In another embodiment, as Figure 3As shown, the four load-bearing columns 3-1’, 3-2’, 3-3’ and 3-4’ are arranged in the same direction helix and are evenly spaced from each other, forming a central rotation structure. In another embodiment, as Figure 4 shown, the mesh load-bearing structure 3 is composed of three load-bearing columns 3-1”, 3-2” and 3-3”. They are arranged in the same direction helix and are evenly spaced from each other. An odd number of load-bearing columns (such as three, five and seven) can only adopt the central rotation setting, while an even number of load-bearing columns (such as four, six or eight) can adopt the symmetric setting to minimize the occlusion in the middle. It should be understood that the number, position of the load-bearing columns and the arrangement of the welding points here are only examples and not restrictive requirements. The embodiments of the present invention can be adjusted and optimized according to the actual application requirements to adapt to different test conditions and sample characteristics.

[0034] In this embodiment, each load-bearing column 3-1, 3-2, 3-3 and 3-4 of the mesh load-bearing structure 3 is designed with an internal cavity. These cavities allow resistance wires to be inserted into the load-bearing columns, so as to heat the sample 4 during the stretching process, which is applicable to the application scenarios that require mechanical tests under high-temperature conditions. In this embodiment, the diameter of the load-bearing column is 3 times the diameter of the resistance wire, ensuring that the resistance wire is accommodated in the cavity of the load-bearing column while ensuring the strength and stability of the structure. In another embodiment, liquid nitrogen can be poured into the cavity of the load-bearing column to precisely control the temperature field of the sample 4 during the stretching process. This design is particularly applicable to the application scenarios that require mechanical tests under low-temperature conditions. In yet another embodiment, the load-bearing column does not have an internal cavity and its diameter is 1 mm. This simplified design may be applicable to experiments that do not require temperature control, or when the structural strength and stability are not the main considerations.

[0035] In this embodiment, the first motor 5 and the second motor 6 are respectively welded below the first fixing plate 1 and above the second fixing plate 2 through four-side reinforcing ribs and are located inside the mesh load-bearing structure 3. This installation method not only ensures the firm connection between the motor and the fixing plate, but also realizes the compact design of the device. By placing the motors inside the mesh load-bearing structure, the external dimensions of the device can be reduced while maintaining the stability and functionality of the structure, which is particularly important for application environments with limited space.

[0036] In this embodiment, the coordinated operation of the first motor 5 and the second motor 6 enables in-situ stretching of the sample 4. This design enables X-ray imaging of the sample 4 while it is under stress. Compared to the conventional method of fixing only one end at the top or bottom and stretching the other end, the present invention allows for simultaneous displacement and stretching of the top and bottom ends of the sample 4. This bidirectional stretching capability not only improves the uniformity of the sample's stress and the precision of control, but also facilitates a more comprehensive study of the microstructural evolution and performance changes of materials under mechanical loading.

[0037] In this embodiment, the first motor 5 and the second motor 6 are piezoelectric coaxial displacement motors, respectively, used to precisely control the displacement and stretching of the sample 4. These motors ensure that the device operates within a loading range of 50mN-1N, with a displacement accuracy greater than 500nm, meeting the requirements of high-precision testing.

[0038] like Figure 1 As shown, the unobstructed imaging in-situ tensile testing device of a preferred embodiment of the present invention further includes an integrated control box 7 , which is fixedly mounted on the second fixed plate 2 and is used to control the movement of the first motor 5 and the second motor 6 .

[0039] In this embodiment, the integrated control box 7 is connected to the first motor 5 and the second motor 6 respectively through wires or cables to achieve precise control of the motors, thereby controlling the in-situ stretching of the sample 4 to achieve precise mechanical loading and imaging.

[0040] In this embodiment, the synchrotron radiation nano-3D imaging process is as follows: First, the sample 4 is clamped between the first motor 5 and the second motor 6. The integrated control box 7 controls the two motors to move in opposite directions to drive the sample 4 to be loaded and stretched. During this process, X-rays are irradiated onto the sample 4 in an unobstructed direction perpendicular to the paper surface (see Figure 2 ) to ensure that there is no obstruction during the imaging process. Subsequently, the air-floating turntable rotates to achieve continuous image acquisition from 0 to 90 degrees, such as Figure 5 As shown. Next, the first motor 5 and the second motor 6 move simultaneously, causing the sample 4 to shift upward by half the length of the spring pitch, while the entire device moves downward by half the length of the spring pitch, so that the position of the sample 4 remains unchanged. This adjustment ensures that there is no obstruction in the original blocking direction, so that continuous image acquisition can be performed for the remaining 90°-180°, as shown. Figure 6 As shown. Finally, through image registration processing, continuous 0-180° image acquisition of the same area is completed. This step integrates images acquired from different angles to generate a complete 3D image of the sample. Subsequently, controlled by the integrated control box 7, the experiment can be automated to complete unobstructed image acquisition under the remaining loading and holding conditions.

[0041] In an embodiment where four preferred load-bearing columns 3-1, 3-2, 3-3, and 3-4 are symmetrically arranged, the occlusion within 180° occurs only once. The continuous acquisition of the entire 180° image consists of the continuous acquisition from 0° to 90° and the continuous acquisition of the remaining 90° - 180° after offset. Finally, through image registration processing, the continuous image acquisition of 0° - 180° in the same area is completed. In other embodiments where the load-bearing columns are rotatably arranged at the center, the number of occlusions within 180° is equal to the number of load-bearing columns. Taking three load-bearing columns as an example, the continuous acquisition of the entire 180° image consists of the continuous acquisition from 0° to 60°, the continuous acquisition of 60° - 120° after offset, and the continuous acquisition of the remaining 120° - 180°. Finally, through image registration processing, the continuous image acquisition of 0° - 180° in the same area is completed.

[0042] In the present invention, it is not required that there must be no occlusion during the imaging process. Instead, the occlusion caused by the load-bearing columns is ultimately avoided by adjusting the position of the sample 4 up and down. The pitch of the load-bearing column is preferably one spot height (generally 2 mm - 4 mm) for just imaging. The diameter of the load-bearing column is 1 / 20 of the spot height, and the offset is half of the spot height, so as to supplement the occluded image. When the offset of the sample 4 enables the continuous acquisition of the 0° - 180° image, its offset should be much greater than 10 times the displacement accuracy of the motors 5 and 6 or the image resolution to avoid the image registration error caused by the displacement amount.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various changes can be made to the above embodiments of the present invention. That is, all simple, equivalent changes and modifications made according to the claims and the content of the specification of the present invention application fall within the scope of the claims of the present invention patent. Those not described in detail in the present invention are all conventional technical contents.

Claims

1. An in-situ tensile test device for unobstructed imaging, characterized in that, The unobstructed imaging in-situ tensile test device includes a first fixing plate, a second fixing plate, a mesh bearing structure, a first motor and a second motor. Among them, the first fixing plate and the second fixing plate are elastically connected through the mesh bearing structure; the first motor is fixedly installed on the first fixing plate, and the second motor is fixedly installed on the second fixing plate; inside the mesh bearing structure, both ends of the sample are respectively connected to the first motor and the second motor to realize the stretching of the sample through the movement of the first motor and the second motor; the mesh bearing structure allows X-rays to pass through unobstructed so as to image the sample.

2. The unobstructed imaging in-situ tensile test device according to claim 1, wherein The mesh bearing structure includes a number of stainless steel bearing columns.

3. The in-situ tensile test device for unobstructed imaging according to claim 2, characterized in that, Four bearing columns are welded together by gradually rotating 90° with equal diameter and spacing.

4. The in-situ tensile test device for unobstructed imaging according to claim 3, characterized in that The spiral directions of the first bearing column and the fourth bearing column are opposite, and their starting points and ending points overlap with each other and are connected by welding; the second bearing column and the third bearing column are also arranged with opposite spiral directions, and their starting points and ending points overlap with each other and are connected by welding; these bearing columns are also connected by welding at the intermediate intersection points to form a symmetric overall structure.

5. The in-situ stretching test device for unobstructed imaging according to claim 2, characterized in that, Each bearing column is designed with an internal cavity to insert a resistance wire or pour liquid nitrogen.

6. The in-situ tensile test device for unobstructed imaging according to claim 1, characterized in that The first motor and the second motor are respectively welded below the first fixing plate and above the second fixing plate through four-side reinforcing ribs and are located inside the mesh bearing structure.

7. The in-situ stretching test device for unobstructed imaging according to claim 1, characterized in that The first motor and the second motor are respectively piezoelectric coaxial displacement motors to precisely control the displacement and stretching of the sample.

8. The non-occlusive imaging in-situ tensile test device according to claim 1, characterized in that, The unobstructed imaging in-situ tensile test device further includes an integrated control box, which is fixedly installed on the second fixing plate and is connected to the first motor and the second motor through wires or cables to realize the precise control of the motors.

9. The three-dimensional imaging method of the unobstructed imaging in-situ tensile test device according to any one of claims 1-8, characterized in that The three-dimensional imaging method includes the following steps: S1, drive the sample to be loaded and stretched by the first motor and / or the second motor. At this time, the X-ray irradiates the sample unobstructed. S2, realize continuous image acquisition within the first angle range. S3, the first motor and the second motor move simultaneously to make the sample shift upward by the length of half a spring pitch, and at the same time the whole device moves downward by the length of half a spring pitch to keep the position of the sample unchanged. S4, realize continuous image acquisition within the second angle range, and the second angle range is complementary to the first angle range and jointly covers the imaging angle of 0-180°. S5, through image registration processing, integrate the 0-180° continuous image acquisition of the same area to generate a complete three-dimensional image of the sample.

10. The three-dimensional imaging method according to claim 9, wherein, The first angle range is 0-90°, and the second angle range is 90°-180°.

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