Experimental device for dynamic reconstruction and visualization monitoring of micro-contact force chains of granular materials

Abstract

The application discloses an experimental device for monitoring and visualizing dynamic reconstruction of micro-contact force chains of granular materials, comprising a shearing shaft, a working part at the bottom, and a shaft diameter gradually decreasing from top to bottom, the bottom of the shearing shaft being matched with a through hole corresponding to a shearing box, and being in contact with the granular materials to be monitored for generating shearing and extrusion stress.The innovation value of the application lies in that the dynamic reconstruction of micro-contact force chains of granular materials and the real-time monitoring and visualization thereof can be realized, the "black box" problem long plagued by the research on granular materials is solved, a multi-scale correlation model of micro-force chain evolution and macro-mechanical response is established, a key experimental means is provided to break through the existing process technology bottleneck, and therefore the scientificity of setting of key parameters of a simulation model and the reliability of a prediction result are remarkably improved, so as to provide a theoretical basis for process optimization.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of metal powder processing, powder metallurgy, and powder rolling and extrusion, and relates to a technology for visual monitoring of dynamic reconstruction of micro contact force chains of granular materials, in particular to an experimental device for visual monitoring of dynamic reconstruction of micro contact force chains of granular materials. BACKGROUND

[0002] Metal powder processing, powder metallurgy, and powder rolling and extrusion manufacturing processes play a core role in the field of high-end equipment, and their importance mainly lies in breaking through the performance limits of traditional materials, realizing integrated forming of complex structures, and promoting innovation in lightweight design.

[0003] Although metal powder processing, powder metallurgy, and powder rolling and extrusion processes have unique advantages in the field of high-end equipment, they still face many technical bottlenecks under the coupling action of multiple scales and multiple physical fields. These bottlenecks limit the further improvement of their process performance and restrict their widespread industrial application under extreme working conditions. From the perspective of the process chain, the current technical system faces challenges in three key dimensions: (1) In the raw material pretreatment stage, the main problems include poor powder flowability, poor mixing uniformity, and segregation of powders with different densities and particle sizes; (2) In the forming processing stage, the density gradient is significant, the residual porosity is high, the demolding damage, sintering deformation and cracking defects exist; (3) In the interface engineering stage, there are key technical problems such as insufficient interface bonding strength and unstable surface quality.

[0004] Through systematic experimental research and theoretical analysis, it is found that the essential mechanism of these apparent process defects can be traced back to the dynamic evolution instability of the micro contact force chain network structure of the particle system. Specifically, (1) the force chain mechanism of the raw material processing problem: the poor flowability of the powder is due to the formation of a percolation rigid force chain network during static piling, whose topological structure hinders the rearrangement movement of the particles; the poor mixing uniformity is due to the force chain clusters in the multi-component system; and the segregation phenomenon is due to the difference in the fractal dimension of the force chain network caused by the difference in particle size / density; (2) the force chain root of the forming defect: the significant pressing density gradient is caused by the stress arch effect, which shows the spatial heterogeneity of the force chain network; the residual pore is directly related to the force chain fracture, and the micro pore nucleus is formed at the fracture; the demolding damage corresponds to the elastic rebound instability of the force chain network; and the sintering deformation is caused by the thermodynamic non-equilibrium evolution of the force chain network; (3) the force chain nature of the interface problem: the insufficient interface bonding strength is due to the low transmission efficiency of the force chain at the rolling interface; the poor surface quality is caused by the fracture or peeling of the surface layer particles due to the concentration of shear force chains, which is directly related to the shear instability of the force chain network. As can be seen, the force chain network is the core structure of the particle material bearing, and its dynamic evolution directly affects the compression, flow, densification and other behaviors of the material. By studying the evolution of the force chain, a correlation model between the micro force chain and the macro mechanical properties can be established, which deepens the understanding of the constitutive relationship of powder materials, and is expected to realize the precise regulation of the structural characteristics and dynamic behavior of the force chain network, so as to systematically solve the technical bottlenecks in metal powder processing, powder metallurgy and other processes, and promote the overall improvement of technical performance.

[0005] At present, the research on the structural characteristics and evolution of the micro contact force chain network of particle materials is mainly through simulation means, and the experimental research mainly focuses on the structural characteristics of the force chain of the static particle system, and the experimental research on the dynamic reconstruction of the force chain is almost blank, which is mainly caused by the fundamental limitations of the technical level and the lack of theoretical methods. Specifically: (1) in the imaging technology, the industrial CT scanning frequency is low, which cannot capture the instant of force chain fracture / recombination; in addition, high-speed photography cannot penetrate three-dimensional particle layers, and the cost of synchrotron radiation source is extremely high; (2) in the force measurement technology, the photoelasticity method is limited by the transparency of the particles, and the pressure-sensitive film can only measure the boundary force, but cannot measure the contact force between the particles; (3) in the theoretical method, due to the lack of dynamic constitutive theory and theoretical guidance in the field of cross-scale correlation fracture, the breakthrough of the technical bottlenecks in metal powder processing, powder metallurgy and other processes is limited. Based on the above research status and difficulties, relying on the support of national key projects, using the method of combining simulation and experiment, the key scientific problems in the theory of particle system are explored, so as to design the experimental device. SUMMARY

[0006] The present application aims to solve at least one of the technical problems existing in the prior art; for this purpose, the present application provides an experimental device for visual monitoring of dynamic reconstruction of micro contact force chains of particulate materials, which is used to solve the technical problem that experimental research on dynamic reconstruction of force chains is almost blank, and the present application captures the structural characteristics of the force chain of the particulate system and the dynamic evolution law of the fracture-reconstruction of the force chain structure under the action of shearing through the cooperation of the rotating shearing system and the optical imaging system, thereby solving the above problems.

[0007] To achieve the above-mentioned purpose, the first aspect of the present application provides an experimental device for visual monitoring of dynamic reconstruction of micro contact force chains of particulate materials, which comprises a shearing shaft, the bottom of which is a working part and the shaft diameter gradually decreases from top to bottom, the bottom of the shearing shaft is matched with the through hole corresponding to the shearing box, and is in contact with the particulate material to be monitored, for generating shearing and extrusion stress;

[0008] The shearing box is arranged below the shearing shaft, the upper end of the shearing box is open and the bottom is transparent, and is used to place the particulate material to be monitored, the bottom of the shearing box is provided with a matched through hole corresponding to the shearing shaft, and is arranged to be able to move up and down, so as to adjust the position of the shearing box in the axial direction of the shearing shaft, and dynamically control the extrusion stress suffered by the particulate material to be monitored in the shearing box;

[0009] The optical imaging unit is arranged along the axial direction of the shearing shaft, and the shearing box is located in the middle of the optical imaging unit, the optical axis direction of the optical imaging unit is parallel to the axial direction of the shearing shaft, the optical imaging unit comprises a high-speed camera, a light source and a light path assembly, any optical element in the light path assembly is arranged to be able to translate or rotate along the optical axis direction;

[0010] The driving unit is used for driving the shearing shaft, and the driving unit is arranged to be able to move along the axial direction of the shearing shaft, so as to ensure the parallelism between the transmission plane of the driving unit and the shearing shaft section.

[0011] Further, any optical element in the light path assembly is installed through a pin shaft clamp, and the angle adjusting mechanism between the optical element and the pin shaft clamp adopts a threaded coupling design.

[0012] Further, the optical element in the angle adjusting mechanism is axially compressed and fixed through an upper end face adjusting bolt, and the static friction effect of the bolt-pin shaft interface is used to maintain the angle locking state; when the rotation angle is adjusted, the bolt pretightening force is gradually released through the controllable torque wrench, so that the optical element rotates around the pin shaft rotation center.

[0013] The experimental method of the experimental device for visual monitoring of dynamic reconstruction of micro contact force chains of particulate materials, the experimental method is applied to the experimental device;

[0014] The particle material to be monitored is placed in the shear box in a flat manner, and the bottom of the shear shaft is matched with the through hole corresponding to the shear box and is in contact with the particle material to be monitored.

[0015] The translational movement of the optical element along the optical axis direction (vertical direction) and the rotational movement in the horizontal plane are adjusted, and multi-degree-of-freedom cooperative adjustment is performed to realize polarization control of the optical path.

[0016] The position of the shear box relative to the axis direction of the shear shaft is adjusted to dynamically control the extrusion stress of the particle material to be monitored in the shear box.

[0017] The rotational speed of the shear shaft is adjusted to change the extrusion stress.

[0018] The light generated by the square light source passes through the optical element below the shear box, the shear box and the particle material to be monitored, and the optical element above the shear box in turn, and is finally captured by the high-speed camera.

[0019] Based on the photoelastic experiment principle, the force chain structure characteristics of the particle material to be monitored in the shear box are captured by the high-speed camera, and the dynamic evolution law of the force chain structure fracture and reconstruction under the shear action.

[0020] Compared with the prior art, the beneficial effects of the present application are:

[0021] 1) Realize the visual real-time monitoring of the dynamic evolution law of the force chain structure characteristics and the fracture and reconstruction of the particle material under continuous shear action;

[0022] 2) Adopt innovative modular coupling design concept to realize cooperative optimization of multifunctional system.

[0023] 3) Adopt optical imaging system, based on kinematic installation principle, each optical element is equipped with coarse and fine adjustment mechanism to support real-time polarization state calibration during experiment;

[0024] 4) For the rotary shear system, the relative position of the shear box and the shear shaft is adjusted by the displacement platform to dynamically control the extrusion stress of the elastoplastic particle in the shear box, break the fixed boundary limitation of the traditional shear box, and realize independent control of the shear-extrusion combined load.

[0025] 5) The innovation value of the present application is that the dynamic reconstruction of the micro contact force chain of the granular material and the real-time monitoring of the visualization can be realized, the long-term "black box" problem of the granular material research is solved, the multi-scale correlation model of the micro force chain evolution and the macro mechanical response is established, the key experimental means is provided to break through the existing process technology bottleneck, and the scientificity of the simulation model key parameter setting and the reliability of the prediction result are significantly improved, so as to provide a theoretical basis for process optimization; this technical breakthrough not only can effectively improve the product quality, but also will promote the metal powder processing technology to realize a leap-forward development in the direction of high precision, high performance and high stability, and finally provide solid technical support for the high-end equipment manufacturing field;

[0026] 6) The scheme adopted by the present application has relatively low cost compared with the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 is a schematic view of the present application.

[0029] Figure 2 is another angle schematic view of the present application.

[0030] Figure 3 is an enlarged schematic view of the shear shaft position of the present application.

[0031] Figure 4 is a schematic view of the pin shaft clamp and the optical element connection of the present application.

[0032] Figure 5 is a schematic view of the rectangular groove installation side stand of the present application.

[0033] Figure 6 is a schematic view of the installation side plate and the clamping block connection of the present application.

[0034] In the figure: base plate 1, rectangular groove installation side stand 2, fixed cross beam 3, high-speed camera 4, plane polarizer 5, 1 / 4 wave plate 6, shear shaft 7, transparent base plate 8, annular side wall 9, installation side plate 10, displacement platform A 11, square light source 12, rectangular installation platform 13, displacement platform B 14, motor 15, transmission belt 16, installation back plate 17, shear shaft installation support 18, pin shaft clamp 19, clamping groove 20, sliding block 21, clamping block 22. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0036] Embodiment 1, please refer to Figures 1-4 Figure, the first aspect of the present application provides an experimental device for visual monitoring of dynamic reconstruction of micro-contact force chains of granular materials, which comprises a rotary shear system, a set of 1 / 4 wave plates 6, a plane polarizer 5 and a high-speed camera 4 are sequentially arranged upward on the rotary shear system, another set of 1 / 4 wave plates 6, a plane polarizer 5 and a square light source 12 are sequentially arranged downward on the rotary shear system; the rotary shear system, the high-speed camera 4, the 1 / 4 wave plate 6, the plane polarizer 5 and the square light source 12 are coaxially arranged;

[0037] Based on the kinematic constraint principle, the optical elements (plane polarizer 5, 1 / 4 wave plate 6) are fixedly installed on the bearing surface of the displacement platform through the pin shaft clamp, and the spatial arrangement of the 1 / 4 wave plate 6 and the plane polarizer 5 strictly follows the polarization interference sequence from top to bottom: primary plane polarizer→first 1 / 4 wave plate→second 1 / 4 wave plate→secondary plane polarizer.

[0038] The two sets of 1 / 4 wave plates 6 and plane polarizers 5 are connected on the two adjustable supports through the displacement platform A11 respectively, the adjustable supports are connected on the bottom plate 1, the fixed cross beam 3 is further fixedly connected on the top of the two adjustable supports, the fixed cross beam 3 is provided with a light transmission hole in the middle part and is fixedly connected with the high-speed camera 4 at the position, and the lens of the high-speed camera 4 is opposite to the light transmission hole; the square light source 12 is fixedly installed on the bottom plate 1.

[0039] The rotary shear system comprises a shear box (transparent bottom plate 8, annular side wall 9), a shear shaft 7, a transmission belt 16 and a shear shaft mounting bracket 18, the shear shaft 7 is vertically arranged in the shear box, and the middle part of the shear shaft 7 is rotatably connected in the mounting hole of the shear shaft mounting bracket 18 through an angular contact bearing; the shear shaft 7 adopts a gradient diameter configuration design from top to bottom, and the rotation of the shear shaft 7 realizes directional shear driving of the elastic-plastic two-dimensional particle system in the shear box.

[0040] The shear box comprises a transparent bottom plate 8 and an annular sidewall 9, the lower end of the annular sidewall 9 is fixedly connected to the transparent bottom plate 8; a through hole is formed on the transparent bottom plate 8 corresponding to the position of the shear shaft 7, the lower end of the shear shaft 7 passes through the through hole and is arranged, and the shear shaft 7 is a hollow shaft. The annular sidewall 9 is connected to the mounting back plate 17 through a displacement platform A11, so as to realize the up-down adjustment of the shear box, cooperate with the shear shaft with a gradient diameter configuration design, realize the controllable loading of the extrusion stress, and the position of the shear box and the shear shaft is relatively adjustable, so as to dynamically control the extrusion stress suffered by the elastic-plastic particles in the shear box. The annular sidewall 9 and the displacement platform A11 form an adjustable rigid connection, and the transparent bottom plate 8 is glued to the precisely machined stepped surface of the annular sidewall 9, so as to ensure the isotropy of the interface mechanics transmission.

[0041] The shear shaft mounting bracket 18 is fixedly connected to the mounting back plate 17, and the two ends of the mounting back plate 17 are fixedly connected to the adjustable brackets on the two sides; the shear box is also connected to the mounting back plate 17 through a corresponding displacement platform A11.

[0042] The surface of the shear shaft 7 is also provided with a belt groove, the shear shaft 7 is drivingly connected to the fixed belt pulley on the output shaft of the motor 15 through the transmission belt 16, the motor 15 is rigidly connected to the rectangular mounting platform 13 through a displacement platform B14, and the rectangular mounting platform 13 is fixedly connected to the bottom plate 1. The adjustment mechanism of the motor 15 enables the transmission system composed of the shear shaft 7, the transmission belt 16 and the motor 15 to be adjusted in a collimation mode, so as to realize the precise adjustment of the position of the motor in the vertical direction, and thus ensure the parallelism between the transmission plane where the transmission belt 16 is located and the horizontal reference plane.

[0043] A groove is formed on the mounting back plate 17 for the transmission belt 16 to pass through.

[0044] The transmission system, the shear shaft and the shear box constitute a stress loading control system, the stress loading control system adopts a modular mechanical coupling design, the mounting back plate 17 is rigidly connected to the rectangular groove mounting side stand 2 through bolts, and a high-precision displacement platform B14 is installed on the working surface.

[0045] As Figure 4The shaft hole of the pin shaft structure and the through hole of the adjusting screw bolt are arranged on the side of the support of the plane polarizer 5 or the 1 / 4 wave plate 6, the adjusting screw bolt is fixedly connected to the opening of the pin clamp 19, the pin clamp 19 is provided with a C-shaped notch, the C-shaped notch is used for connecting the support of the plane polarizer 5 or the 1 / 4 wave plate 6, the pin clamp 19 is fixedly connected to the displacement platform A11, the axis of the adjusting screw bolt connected to the opening of the pin clamp 19 is arranged vertically, a through hole for the adjusting screw bolt is arranged at one end of the pin clamp 19, and a threaded hole for screwing the adjusting screw bolt is arranged at the other end of the pin clamp 19.

[0046] In addition, the displacement platform A11 cooperates with the pin clamp 19 to enable the optical element (the plane polarizer 5 or the 1 / 4 wave plate 6) to perform translational motion along the optical axis direction (the vertical direction) and rotational motion in the horizontal plane, so that multi-degree-of-freedom cooperative adjustment of the optical imaging system is realized, and the flexibility of polarization regulation of the optical path and the experimental repeatability are improved.

[0047] The angle adjustment mechanism between the optical element (the plane polarizer 5 or the 1 / 4 wave plate 6) and the pin clamp is designed by using thread coupling, each optical element is axially pressed and fixed by the adjusting screw bolt, and the angle locking state is maintained by the static friction effect of the contact interface between the pin clamp 19 and the pin shaft structure; when the rotation angle is adjusted, the bolt pretightening force is gradually released by the controllable torque wrench, so that the optical element rotates around the rotation center of the pin shaft; the mechanism meets the real-time calibration requirement of the polarization direction of the optical element in the dynamic experiment process, and ensures the long-term stability of the polarization optical path system.

[0048] The adjustable support includes a rectangular groove mounting side stand 2 and a mounting side plate 10, each adjustable support includes two rectangular groove mounting side stands 2, and a plurality of mounting side plates 10 are connected between the two rectangular groove mounting side stands 2, and the mounting side plate 10 is used for connecting the support of the plane polarizer 5 or the 1 / 4 wave plate 6.

[0049] As shown in Figure 5 , a plurality of clamping grooves 20 are arranged at equal distances on one side of the rectangular groove mounting side stand 2, the lower end of the rectangular groove mounting side stand 2 is integrally formed into a sliding block 21 and is slidingly connected to the bottom plate 1, and the bottom plate 1 and the sliding block 21 are connected by a bolt, that is, the bolt passes through the bottom plate 1 and is threadedly connected to the sliding block 21, so that the bottom plate 1 and the sliding block 21 are fixed.

[0050] As shown in Figure 6One side of the mounting side plate 10 is fixedly connected with two clamping blocks 22.

[0051] The clamping blocks 22 of the mounting side plate 10 are clamped with the clamping grooves 20, and the clamping blocks 22 and the clamping grooves 20 can be fixedly connected through screws. The connection mode of the clamping blocks 22 and the clamping grooves 20 realizes the coarse adjustment of the position of the mounting side plate 10, and further realizes the coarse adjustment of the position of the optical element connected with the mounting side plate 10, and the fine adjustment is realized through the displacement platform; meanwhile, the modular connection mode is realized.

[0052] Similarly, the mounting back plate 17 and the rectangular groove mounting side plate 2 can also adopt the same modular design.

[0053] Embodiment 2, experimental method of experimental device for visual monitoring of dynamic reconstruction of micro contact force chain of granular material, the method is applied to the experimental device;

[0054] The method comprises the following steps of: placing the granular material to be monitored in the shear box and laying the granular material to be monitored in the shear box; the bottom of the shear shaft is matched with the through hole corresponding to the shear box and is in contact with the granular material to be monitored;

[0055] Adjusting the translational motion of the optical element along the optical axis direction (vertical direction) and the rotational motion in the horizontal plane, performing multi-degree-of-freedom cooperative adjustment, and realizing polarization control of the optical path;

[0056] Adjusting the position of the shear box relative to the axis direction of the shear shaft, and dynamically controlling the extrusion stress suffered by the granular material to be monitored in the shear box;

[0057] Adjusting the rotating speed of the shear shaft to change the extrusion stress;

[0058] The light generated by the square light source passes through the optical element below the shear box, the shear box and the granular material to be monitored, and the optical element above the shear box in sequence, and is finally captured by the high-speed camera;

[0059] Based on the photoelastic experiment principle, the force chain structure characteristics of the granular material to be monitored in the shear box are captured by the high-speed camera, and the dynamic evolution law of the force chain structure fracture and reconstruction under the shear action is obtained.

[0060] The method further comprises the following steps of: controlling the shear speed, and realizing the control by changing the rotating speed of the motor driving the shear shaft 7.

[0061] The method further comprises the following steps of: realizing different filling schemes by filling elastoplastic particles with different characteristic parameters, such as particle size, particle size distribution, friction coefficient and the like.

[0062] The above examples are only used to illustrate the technical method of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical method of the present application.

Claims

1. An experimental apparatus for visual monitoring of dynamic reconfiguration of microscopic contact force chains in particulate materials, characterized in that, include: The shearing shaft has a working part at the bottom and the shaft diameter gradually decreases from top to bottom. The bottom of the shearing shaft matches the through hole corresponding to the shearing box and contacts the particle material to be monitored to generate shear and compressive stress. The shear box is positioned below the shear shaft. The upper end of the shear box is open and the bottom is transparent. It is used to place the particulate material to be monitored. The bottom of the shear box has a through hole corresponding to the shear shaft and is configured to move up and down. Adjusting the position of the shear box relative to the axial direction of the shear shaft can dynamically control the compressive stress on the particulate material to be monitored inside the shear box. An optical imaging unit is configured along the axial direction of the shear axis, and the shear box is located in the middle of the optical imaging unit. The optical axis of the optical imaging unit is parallel to the axial direction of the shear axis. The optical imaging unit includes a high-speed camera, a light source, and an optical path assembly. The optical path assembly includes multiple optical elements, and any optical element in the optical path assembly is configured to be able to translate or rotate along the optical axis. A drive unit is used to drive the shear shaft. The drive unit is configured to move along the axial direction of the shear shaft to ensure the parallelism between the drive unit and the transmission plane of the shear shaft and the cross section of the shear shaft. An optical element and a high-speed camera are arranged sequentially above the shearing shaft; an optical element and a square light source are arranged sequentially below the shearing box. The optical element is connected to adjustable brackets on both sides via a displacement platform A, and the adjustable brackets are connected to the base plate. The middle part of the shearing shaft is rotatably connected to the mounting hole opened on the shearing shaft mounting bracket through an angular contact bearing; the surface of the shearing shaft is also provided with a belt groove, and the shearing shaft is connected to a fixed pulley on the motor output shaft through a transmission belt. The shearing box includes a transparent base plate and an annular sidewall, with the lower end of the annular sidewall fixedly connected to the transparent base plate; a through hole is provided on the base plate at the position corresponding to the shearing shaft, and the lower end of the shearing shaft passes through the through hole; the shearing shaft is a hollow shaft. The shear shaft mounting bracket is fixedly connected to the mounting back plate, and the two ends of the mounting back plate are fixedly connected to the adjustable brackets on both sides. The motor is rigidly connected to the rectangular mounting platform through the displacement platform B, and the rectangular mounting platform is fixedly connected to the base plate. The optical element includes a plane polarizer and a quarter-wave plate. Both the plane polarizer and the quarter-wave plate have a pin structure formed on one side of their support, and the pin structure is rotatably connected to a pin clamp.

2. The experimental apparatus for visual monitoring of dynamic reconstruction of microscopic contact force chains in particulate materials according to claim 1, characterized in that, Any optical element in the optical path assembly is mounted via a pin clamp, and the angle adjustment mechanism between the optical element and the pin clamp adopts a threaded coupling design.

3. The experimental apparatus for visual monitoring of dynamic reconstruction of microscopic contact force chains in particulate materials according to claim 2, characterized in that, In the angle adjustment mechanism, the optical element is axially clamped and fixed by the upper end adjustment bolt, and the angle is maintained in a locked state by the static friction effect of the bolt pin interface. When adjusting the rotation angle, the bolt preload is gradually released by the controllable torque wrench, so that the optical element rotates slightly around the pin center.

4. The experimental apparatus for visual monitoring of dynamic reconstruction of microscopic contact force chains in particulate materials according to claim 3, characterized in that, The adjustable bracket includes a rectangular slot mounting side plate and a mounting side plate. Each adjustable bracket includes two rectangular slot mounting side plates, and multiple mounting side plates are connected between the two rectangular slot mounting side plates. The rectangular groove mounting side plate has several slots evenly spaced on one side. The lower end of the rectangular groove mounting side plate is integrally formed into a slider and slidably connected to the base plate. The slider and the base plate are fixedly connected by bolts to achieve a fixed connection between the rectangular groove mounting side plate and the base plate. Two clips are fixedly connected to one side of the mounting side plate; The mounting plate is attached to the mounting slot.

5. The experimental method based on the experimental apparatus for visual monitoring of dynamic reconstruction of microscopic contact force chains in particulate materials as described in claim 1, characterized in that, The experimental method is applied to the above-described experimental apparatus; This includes placing the particulate material to be monitored in a shear box and laying it flat, with the bottom of the shear shaft matching the corresponding through hole in the shear box and in contact with the particulate material to be monitored; By adjusting the translational motion of the optical element along the optical axis and its rotational motion in the horizontal plane, multi-degree-of-freedom coordinated adjustment can be achieved to realize optical path polarization control; Adjusting the position of the shear box relative to the shear axis in the axial direction dynamically controls the compressive stress on the particle material to be monitored inside the shear box; Adjusting the rotational speed of the shearing shaft changes the compressive stress; The light generated by the square light source passes sequentially through the optical element below the shear box, the shear box and the particle material to be monitored, the optical element above the shear box, and is finally captured by the high-speed camera. Based on the principle of photoelasticity experiments, a high-speed camera was used to capture the force chain structure characteristics of the particle material to be monitored in the shear box, as well as the dynamic evolution law of force chain structure fracture and reconstruction under shearing.

6. The experimental method of the experimental apparatus for visual monitoring of dynamic reconfiguration of microscopic contact force chains in particulate materials according to claim 5, characterized in that, The method also includes achieving different filling schemes by filling elastoplastic particles with different characteristic parameters.

7. The experimental apparatus for visual monitoring of dynamic reconstruction of microscopic contact force chains in particulate materials as described in claim 1 is used to capture the force chain structure characteristics of particulate systems and to capture the dynamic evolution law of force chain structure fracture to reconstruction in particulate systems under shear action.

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