A photoelastic test device and test method based on ring shear instrument

Abstract

The invention provides a photoelastic test device and test method based on a ring shear instrument. The photoelastic test device includes a ring shear instrument main structure, a power device, a data acquisition device and a photoelastic device. The main structure of the ring shear instrument is driven by the power device to rotate the lower moving disk, which in turn drives the sample in the middle fixed cylinder to rotate, and finally transmits the force to the upper follower disk through the movement of the sample, and is measured by the force sensor and collected and transmitted by the data acquisition box, wherein the acoustic emission signal is measured by an acoustic emission probe placed in the small hole of the upper follower disk, and is collected and stored by an external acoustic emission instrument. The photoelastic device includes a light source, a polarizer and a photoelastic material sample. The photoelastic test device can measure the friction and dislocation of granular bodies of different particle sizes, and has the characteristics of convenient installation and sampling. The sample will not be squeezed out, and it is easy to place the acoustic emission probe. The photoelastic method can be used to observe and record the test process, and the preliminary test results can be more intuitively understood.

Description

Technical Field

[0001] The present invention relates to the technical field of material detection, and in particular to a photoelastic testing device and a testing method based on a ring shear instrument. Background Art

[0002] my country has a rich variety of terrain, with mountainous areas accounting for two-thirds of the country's total area. Natural disasters such as collapse, landslides, and debris flows occur frequently, so studying the shear properties of granular materials is of great practical significance. The ring shear test can study the shear resistance of materials under large deformation, but the traditional ring shear instrument is not very suitable for the study of granular samples, and the test process cannot be observed. The multifunctional ring shear instrument designed and modified based on this defect has made many improvements on the basis of the traditional ring shear instrument. Combined with acoustic emission technology, it can study the shear of granular materials and the internal friction and dislocation of particles. However, the experiment has high requirements for environmental quietness, the operation is more complicated, and the experimental results require a large amount of data analysis later.

[0003] Some new requirements have been put forward for the above-mentioned device, including: 1) the experiment can be carried out in a more general environment; 2) the instrument can be operated more conveniently; 3) a preliminary understanding of the experimental results can be obtained more intuitively.

[0004] After years of research, photoelasticity has become a mature method for studying stress-strain behavior. Therefore, it is necessary to address the aforementioned shortcomings by developing a visualization instrument suitable for studying shear and internal friction in granular materials, and to combine this with photoelasticity to observe the experimental process. Summary of the Invention

[0005] The purpose of the present invention is to provide a photoelastic testing device and a testing method based on a ring shear instrument to solve the problems existing in the prior art.

[0006] The technical solution adopted to achieve the purpose of the present invention is as follows: a photoelastic testing device based on a ring shear instrument includes a ring shear instrument main structure, a data acquisition device, a graphic recording device and a photoelastic device.

[0007] The main structure of the ring shear instrument includes a lower moving disc, a middle fixed cylinder, an upper follower disc and a middle fixed column.

[0008] The lower moving plate comprises a support plate I, several columns, a rotating cylinder, and gear I. Support plate I rests on the upper surface of the columns. Its surface features coaxially arranged holes and annular mounting grooves. The upper end of the rotating cylinder extends through the hole, while the outer ring of its lower end is fitted with gear I. Gear I is connected to a chain.

[0009] The central fixed cylinder includes an outer cylinder, an inner cylinder, an inner fixed disk, a rotatable ring at the lower end, and a non-rotatable ring at the upper end. The outer cylinder and inner cylinder are made of transparent material. The lower end of the outer cylinder is embedded in an annular embedding groove. The inner cylinder is arranged in the inner cavity of the outer cylinder. The outer cylinder and inner cylinder are coaxially arranged. The inner fixed disk is arranged in a hole. The inner cylinder rests on and is fixed to the inner fixed disk. The outer cylinder and inner cylinder enclose a cylindrical annular storage space. The non-rotatable ring at the upper end and the rotatable ring at the lower end are respectively arranged at the upper and lower ends of the cylindrical annular storage space. The lower surface of the rotatable ring at the lower end is connected to the upper surface of the rotating cylinder. The upper surface of the rotatable ring at the lower end is provided with serrations. The lower surface of the non-rotatable ring at the upper end is provided with serrations. The outer cylinder, inner cylinder, rotatable ring at the lower end, and non-rotatable ring at the upper end together enclose a sample chamber.

[0010] The upper follower disc cover is positioned above the central fixed cylinder. The upper follower disc comprises a disc and a raised barrel. The disc is fixed to the upper surface of the upper non-rotatable ring. The disc seals the upper opening of the inner cylinder. The sidewall of the disc is provided with a plurality of grooves. An acoustic emission probe is disposed in each groove. The lower end of the acoustic emission probe abuts against the upper surface of the upper non-rotatable ring. The raised barrel is a cylindrical structure with an open lower end and a closed upper end. The raised barrel is disposed on the upper surface of the disc. The lower opening of the raised barrel is sealed by the disc. A reserved opening is provided on the sidewall of the raised barrel. A raised block is disposed on the sidewall of the raised barrel next to the reserved opening.

[0011] The column body of the middle fixed column sequentially passes through the inner cavity of the rotating cylinder, the inner fixed disk, the inner cavity of the inner cylinder and the disk, and then extends into the inner cavity of the raised barrel. The inner fixed disk is fixedly connected to the side wall of the middle fixed column.

[0012] The data acquisition device includes a force sensor and a data acquisition box. The handle of the force sensor is removably mounted on the shaft of the central fixed column after passing through a reserved opening. The main body of the force sensor extends to the side of the raised block. The force sensor is connected to the data acquisition box.

[0013] The image recording device includes a plurality of cameras which are arranged around the outside of the central fixed cylinder.

[0014] The photoelastic device includes a light source, a polarizing plate, and a photoelastic material sample. The light source is arranged on a central fixed column. The polarizing plate is attached to the outer wall of the outer cylinder and the inner wall of the inner cylinder.

[0015] During operation, the sample cavity is filled with a photoelastic material sample. The serrations of the upper, non-rotatable ring and the lower, rotatable ring are embedded in the rock and soil sample. A chain drives the rotating cylinder, and the lower, rotatable ring drives the rock and soil sample, transmitting torsional force to the upper follower disk. A light source illuminates the surroundings, causing a photoelastic phenomenon to occur in the photoelastic material sample, and a graphic recording device records the photoelastic image. A force sensor contacts the raised block, measures the torsional force, and transmits it to a data acquisition box. By comparing the photoelastic images, torque, and acoustic emission data at different times, analysis reveals stresses within and between particles.

[0016] Furthermore, the device includes a power unit. The power unit includes a distribution box, a motor, gears, and a chain. The motor is connected to the distribution box. A gear II is provided at the output end of the motor. Gear II is connected to the chain. The distribution box changes the speed of the motor by varying the power it supplies.

[0017] Furthermore, the invention also comprises a base, the lower surface of which is provided with a rubber sheet.

[0018] Furthermore, the lower movable plate further comprises a support plate II. The plurality of upright posts are sandwiched between the support plate I and the support plate II.

[0019] Furthermore, the outer cylinder and the inner cylinder are both made of transparent acrylic material. The photoelastic material sample is made of transparent plastic material. The photoelastic material sample is in the shape of a disc, a sphere or a polyhedron.

[0020] Furthermore, the disc is provided with a pressing sheet which is fixed to the upper surface of the disc by bolts.

[0021] Furthermore, the light source for the photoelastic device is an LED light strip wrapped around a central fixed column. The white light emitted by the light source is evenly distributed all around. The power cord for the light source is routed from the lower rotor plate of the ring shear instrument's main structure to ensure it does not interfere with specimen rotation or the chain drive.

[0022] Furthermore, the polarizer of the photoelastic device is a circular polarizer. Double-sided tape and transparent tape are used to stick the two long sides of each polarizer along the inner wall of the inner tube and the upper and lower circumferences of the outer wall of the outer tube, respectively, so that the polarizer is as close to the tube wall as possible, leaving as much space as possible except for the upper and lower edges for easy observation.

[0023] Furthermore, the image recording device further comprises a ring bracket on which the camera is suspended.

[0024] The present invention also discloses a test method using the above-mentioned photoelastic test device based on the ring shear instrument, which uses photoelastic technology to observe the stripes and force chains that appear during the shearing process of the granular body, and synchronously records the photoelastic graphics at different times, compares them with the torque and acoustic emission data results, and analyzes the stress inside and between the particles.

[0025] The technical effects of the present invention are unquestionable:

[0026] A. It can be used under general laboratory conditions, and the requirements for noise and other factors are not high;

[0027] B. The operation method is relatively easy, the camera and computer are easy and quick to use, and almost no parameters need to be adjusted;

[0028] C. The photoelastic device can observe the stripes and force chains in real time during the experiment;

[0029] D. It can measure the friction and dislocation of granular materials with different particle sizes, and is easy to install and sample, and the sample will not be squeezed out;

[0030] E. The lower support disc and columns, along with the middle column, support and secure the main body, ensuring a secure upper and middle structure and accurate installation and positioning. The outer cylinder is embedded for easy sampling. Transparent acrylic inner and outer cylinders facilitate observation of specimen movement and damage during testing. A serrated ring facilitates engagement with the specimen and transfers torsional forces. A vertically movable upper ring ensures only torsional forces are transferred and allows for easy disassembly.

[0031] F. Reserve a small hole on the upper surface of the non-rotatable ring and a preset pressing piece for the acoustic emission probe to ensure signal reception;

[0032] G. The base is designed with varying heights to ensure horizontal chain transmission and minimize resistance. A rubber pad under the base reduces vibration and noise. The force sensor features a screw handle for easy adjustment and removal. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the overall structure of the photoelastic test device based on the ring shear instrument;

[0034] Figure 2 Schematic diagram of the lower moving disk;

[0035] Figure 3 This is a schematic diagram of the main structure of the ring shear instrument;

[0036] Figure 4 This is a schematic diagram of the power unit;

[0037] Figure 5 Schematic diagram of the structure of the photoelastic device;

[0038] Figure 6 Schematic diagram of the structure of the graphic recording device.

[0039] In the figure: base 1, power device 2, distribution box 201, motor 202, gear II 203, chain 204, data acquisition device 3, force sensor 301, data acquisition box 302, light source 4, lower moving disk 5, support plate I 501, hole 5011, annular embedding groove 5012, support plate II 502, column 503, rotating cylinder 504, gear I 505, middle fixed cylinder 6, outer cylinder 601, inner cylinder 602, inner fixed disk 603, lower end rotatable ring 604, upper end non-rotatable ring 605, upper follower disk 7, disk 701, groove 7011, pressing plate 7012, raised barrel 702, reserved opening 7021, raised block 7022, middle fixed column 8, annular bracket 10, camera 11, polarizer 15, photoelastic material sample 16. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the following examples, but it should not be understood that the scope of the present invention is limited to the following examples. Without departing from the above technical ideas of the present invention, various substitutions and modifications can be made according to common technical knowledge and customary means in the art, and all should be included in the scope of protection of the present invention.

[0041] Example 1:

[0042] Photoelasticity is a method for measuring the stress and strain of an object using optical principles. Its advantages include intuitiveness, a wide measurement range, and non-destructiveness. The photoelastic effect of a material, also known as birefringence, refers to the phenomenon in which a beam of polarized light strikes a transparent material and the emitted light splits into two beams traveling in different directions. Common photoelastic materials include glass, polycarbonate, epoxy resin, and the plastic polypropylene. Polarized light is always a transverse wave and can be divided into linearly polarized light, circularly polarized light, and elliptically polarized light depending on its properties. When the electric vector of a light wave changes regularly over time, and the endpoints of the rotating electric vector trace a circular trajectory, the light is circularly polarized. Based on Maxwell's stress-optics laws, the photoelastic test method has been extensively explored and applied. With the development of materials science and improvements in experimental and analytical instruments, it has gradually been combined with computer technology to form digital photomechanics.

[0043] See also Figure 1 This embodiment provides a photoelastic testing device based on a ring shear instrument, including a ring shear instrument main structure, a base 1, a power device 2, a data acquisition device 3 and a photoelastic device.

[0044] See also Figure 3 The main structure of the ring shear instrument includes a lower movable plate 5, a middle fixed cylinder 6, an upper follower plate 7 and a middle fixed column 8.

[0045] See also Figure 2The lower moving plate 5 includes a support plate I 501, a support plate II 502, a column 503, a rotating cylinder 504 and a gear I 505. The support plate I 501 is placed on the upper surface of the column 503. The column 503 is sandwiched between the support plate I 501 and the support plate II 502.

[0046] The support plate I 501 has a coaxial hole 5011 and an annular fixing groove 5012 . The upper end of the rotating cylinder 504 extends out of the hole 5011 , and the outer ring of the lower end is provided with a gear I 505 . The gear I 505 is connected to the chain 204 .

[0047] The central fixed cylinder 6 comprises an outer cylinder 601, an inner cylinder 602, an inner fixed disk 603, a lower rotatable ring 604, and an upper non-rotatable ring 605. Both the outer cylinder 601 and the inner cylinder 602 are made of transparent acrylic. The lower end of the outer cylinder 601 is embedded in the annular embedding groove 5012. The inner cylinder 602 is disposed within the inner cavity of the outer cylinder 601. The outer cylinder 601 and inner cylinder 602 are coaxially arranged. The inner fixed disk 603 is disposed in the hole 5011. The inner cylinder 602 rests on and is fixed to the inner fixed disk 603. The outer cylinder 601 and inner cylinder 602 enclose a cylindrical housing. The upper non-rotatable ring 605 and the lower rotatable ring 604 are disposed at the upper and lower ends of the cylindrical housing, respectively. The lower surface of the lower rotatable ring 604 is connected to the upper surface of the rotating cylinder 504. The upper surface of the lower rotatable ring 604 is provided with serrations. The lower surface of the upper non-rotatable ring 605 is provided with serrations. The outer cylinder 601, the inner cylinder 602, the lower rotatable ring 604 and the upper non-rotatable ring 605 together enclose a sample chamber.

[0048] The upper follower disc 7 is positioned above the middle fixed cylinder 6. The upper follower disc 7 includes a disc 701 and a raised barrel 702. The disc 701 is fixed to the upper surface of the upper non-rotatable ring 605. The disc 701 blocks the upper opening of the inner cylinder 602. Four grooves 7011 are provided on the sidewall of the disc 701. The four grooves 7011 are arranged in a circular pattern. Adjacent grooves 7011 are spaced 90 degrees apart. Acoustic emission probes are positioned in the grooves 7011. The lower end of the acoustic emission probe is pressed against the upper surface of the upper non-rotatable ring 605. A pressure plate 7012 is provided next to each groove 7011. The pressure plate 7012 is bolted to the upper surface of the disc 701. The pressure plates 7012 enable the acoustic emission probe to capture wave signals with sufficient sensitivity, receiving signals with minimal attenuation.

[0049] The raised barrel 702 is a cylindrical structure with an open lower end and a closed upper end. The raised barrel 702 is disposed on the upper surface of the disc 701. The lower open end of the raised barrel 702 is blocked by the disc 701. A reserved opening 7021 is provided on the sidewall of the raised barrel 702. A raised block 7022 is provided on the sidewall of the raised barrel 702, adjacent to the reserved opening 7021.

[0050] The shaft of the intermediate fixed column 8 sequentially passes through the inner cavity of the rotating cylinder 504, the internal fixed disk 603, the inner cavity of the inner cylinder 602, and the disk 701, before extending into the inner cavity of the raised barrel 702. The intermediate fixed column 8 extends through the upper, middle, and lower portions of the main structure of the ring shear apparatus, providing support and fixation. The internal fixed disk 603 is fixedly connected to the sidewall of the intermediate fixed column 8.

[0051] The data acquisition device 3 includes a force sensor 301 and a data acquisition box 302. The handle of the force sensor 301 passes through a reserved opening 7021 and can be removably mounted on the shaft of the intermediate fixed column 8. The main body of the force sensor 301 extends to the side of the raised block 7022. The force sensor 301 is connected to the data acquisition box 302.

[0052] The image recording device includes six cameras 11. The cameras 11 are arranged around the outside of the central fixed cylinder 6.

[0053] The photoelastic device includes a light source 4, a polarizing plate 15, and a photoelastic material sample 16. The light source 4 is arranged on the middle fixed column 8. The polarizing plate 15 is attached to the outer wall of the outer cylinder 601 and the inner wall of the inner cylinder 602.

[0054] During operation, the sample cavity is filled with a photoelastic material sample 16. The serrations of the upper non-rotatable ring 605 and the lower rotatable ring 604 are embedded in the rock and soil sample. The chain 204 drives the rotating cylinder 504 to rotate, and the lower rotatable ring 604 drives the rock and soil sample to rotate, transmitting the torsional force to the upper follower disk 7. The light source 4 illuminates the surroundings, causing a photoelastic phenomenon to appear in the photoelastic material sample 16, and a graphic recording device records the photoelastic image. The force sensor 301 contacts the raised block 7022 to measure the torsional force and transmit it to the data acquisition box 302. By comparing the photoelastic images, torque, and acoustic emission data at different times, the stress within and between the particles can be analyzed.

[0055] The power unit 2 includes a distribution box 201, a motor 202, a gear II 203, and a chain 204. The motor 202 is connected to the distribution box 201. The output end of the motor 202 is provided with a gear II 203. The gear II 203 is connected to the chain 204. The distribution box 201 changes the speed of the motor 202 by changing the power it provides.

[0056] The base 1 comprises the main structure of the ring shear instrument and a motor lift base. This motor lift base maintains a substantially horizontal transmission of the chain 204, which reduces resistance. A rubber sheet is provided on the lower surface of the base 1 to reduce vibration and noise during operation of the motor 202.

[0057] See also Figure 5 The light source 4 of the photoelastic device is an LED light strip, fixed around the middle column 8, ensuring that the white light emitted during use is evenly illuminated all around. The power cord of the light strip is led out from the lower rotating disk of the ring shear instrument main structure to ensure that it does not interfere with the rotation of the specimen and the chain drive.

[0058] The polarizer 15 of the photoelastic device is a circular polarizer. Double-sided tape and transparent tape are used to stick the two long sides of each polarizer along the inner wall of the inner tube and the upper and lower circumferences of the outer wall of the outer tube, so that the polarizer is as close to the tube wall as possible, leaving as much blank space as possible except for the upper and lower edges for observation.

[0059] The photoelastic material sample 16 of the photoelastic device is made of transparent plastic material and can be in the shape of a disc, a sphere, a polyhedron, etc., and needs to cover the gap between the inner and outer cylinders.

[0060] See also Figure 6 The image recording device includes a bracket 10 and cameras 11. The bracket is positioned around the main structure of the ring shear instrument, with six cameras 11 evenly spaced on the bracket 10. The bracket 10 is a circular steel frame, positioned at half the height of the fixed cylinder 6 in the middle of the ring shear instrument. Platforms 12 are provided every 60 degrees along the upper circumference of the bracket for placing cameras. The cameras 11 can capture both still photos and dynamic videos. Before use, the field of view and shooting frequency must be adjusted.

[0061] Photoelasticity technology is used to observe the stripes and force chains that appear during the shearing process of granular bodies, and the photoelastic patterns at different times are simultaneously recorded. By comparing them with the torque and acoustic emission data results, the stress inside and between particles can be further analyzed.

[0062] It is worth noting that this embodiment does not require a quiet environment for the test and can be performed in a common environment. This makes it easier to operate the instrument and allows for a more intuitive understanding of the test results.

[0063] Example 2:

[0064] This embodiment provides a basic photoelastic testing device based on a ring shear instrument, including a main structure of the ring shear instrument, a data acquisition device 3, a graphic recording device and a photoelastic device.

[0065] The main structure of the ring shear instrument includes a lower movable disc 5, a middle fixed cylinder 6, an upper follower disc 7 and a middle fixed column 8.

[0066] The lower moving plate 5 comprises a support plate I 501, a column 503, a rotating cylinder 504, and a gear I 505. The support plate I 501 rests on the upper surface of the column 503. The surface of the support plate I 501 has a coaxial hole 5011 and an annular retaining groove 5012. The upper end of the rotating cylinder 504 extends out of the hole 5011, and the outer ring of the lower end is fitted with a gear I 505. The gear I 505 is connected to the chain 204.

[0067] The central fixed cylinder 6 comprises an outer cylinder 601, an inner cylinder 602, an inner fixed disk 603, a lower rotatable ring 604, and an upper non-rotatable ring 605. The outer cylinder 601 and inner cylinder 602 are made of transparent material. The lower end of the outer cylinder 601 is embedded in the annular embedding groove 5012. The inner cylinder 602 is disposed within the inner cavity of the outer cylinder 601. The outer cylinder 601 and inner cylinder 602 are coaxially arranged. The inner fixed disk 603 is disposed in the hole 5011. The inner cylinder 602 rests on and is fixed to the inner fixed disk 603. The outer cylinder 601 and inner cylinder 602 enclose a cylindrical housing. The upper non-rotatable ring 605 and the lower rotatable ring 604 are disposed at the upper and lower ends of the cylindrical housing, respectively. The lower surface of the lower rotatable ring 604 is connected to the upper surface of the rotating cylinder 504. The upper surface of the lower rotatable ring 604 is provided with serrations. The lower surface of the upper non-rotatable ring 605 is provided with serrations. The outer cylinder 601, the inner cylinder 602, the lower rotatable ring 604 and the upper non-rotatable ring 605 together enclose a sample chamber.

[0068] The upper follower disc 7 is positioned above the middle fixed cylinder 6. The upper follower disc 7 comprises a disc 701 and a raised barrel 702. The disc 701 is fixed to the upper surface of the upper non-rotatable ring 605. The disc 701 blocks the upper open end of the inner cylinder 602. The sidewall of the disc 701 is provided with multiple grooves 7011. Acoustic emission probes are positioned within the grooves 7011. The lower end of the acoustic emission probe abuts against the upper surface of the upper non-rotatable ring 605. The raised barrel 702 is a cylindrical structure with an open lower end and a closed upper end. The raised barrel 702 is positioned on the upper surface of the disc 701. The lower open end of the raised barrel 702 is blocked by the disc 701. A reserved opening 7021 is provided on the sidewall of the raised barrel 702. A protruding block 7022 is provided on the side wall of the protruding barrel 702 beside the reserved opening 7021 .

[0069] The shaft of the intermediate fixed column 8 passes through the inner cavity of the rotating cylinder 504, the inner fixed disk 603, the inner cavity of the inner cylinder 602 and the disk 701 in sequence, and then extends into the inner cavity of the raised cylinder 702. The inner fixed disk 603 is fixedly connected to the side wall of the intermediate fixed column 8.

[0070] The data acquisition device 3 includes a force sensor 301 and a data acquisition box 302. The handle of the force sensor 301 passes through a reserved opening 7021 and can be removably mounted on the shaft of the intermediate fixed column 8. The main body of the force sensor 301 extends to the side of the raised block 7022. The force sensor 301 is connected to the data acquisition box 302.

[0071] The image recording device includes a plurality of cameras 11. The cameras 11 are arranged around the outside of the central fixed cylinder 6.

[0072] The photoelastic device includes a light source 4, a polarizing plate 15, and a photoelastic material sample 16. The light source 4 is arranged on the middle fixed column 8. The polarizing plate 15 is attached to the outer wall of the outer cylinder 601 and the inner wall of the inner cylinder 602.

[0073] During operation, the sample cavity is filled with a photoelastic material sample 16. The serrations of the upper non-rotatable ring 605 and the lower rotatable ring 604 are embedded in the rock and soil sample. The chain 204 drives the rotating cylinder 504 to rotate, and the lower rotatable ring 604 drives the rock and soil sample to rotate, transmitting the torsional force to the upper follower disk 7. The light source 4 illuminates the surroundings, causing a photoelastic phenomenon to appear in the photoelastic material sample 16, and a graphic recording device records the photoelastic image. The force sensor 301 contacts the raised block 7022 to measure the torsional force and transmit it to the data acquisition box 302. By comparing the photoelastic images, torque, and acoustic emission data at different times, the stress within and between the particles can be analyzed.

[0074] Example 3:

[0075] This embodiment has the same primary structure as that of Embodiment 2, but further includes a power unit 2. The power unit 2 comprises a distribution box 201, a motor 202, a gear II 203, and a chain 204. The motor 202 is connected to the distribution box 201. The output end of the motor 202 is provided with a gear II 203. The gear II 203 is connected to the chain 204. The distribution box 201 changes the speed of the motor 202 by varying the power supplied.

[0076] Example 4:

[0077] The main structure of this embodiment is the same as that of embodiment 2, wherein the embodiment further comprises a base 1. A rubber sheet is provided on the lower surface of the base 1.

[0078] Example 5:

[0079] The main structure of this embodiment is the same as that of embodiment 2, wherein the lower movable plate 5 further includes a support plate II 502. The upright column 503 is sandwiched between the support plate I 501 and the support plate II 502.

[0080] Example 6:

[0081] The main structure of this embodiment is the same as that of embodiment 2, wherein the outer cylinder 601 and the inner cylinder 602 are both made of transparent acrylic material. The photoelastic material sample 16 is made of transparent plastic material. The photoelastic material sample 16 is in the shape of a disc, a sphere, or a polyhedron.

[0082] Example 7:

[0083] The main structure of this embodiment is the same as that of embodiment 2, wherein the disc 701 further has a pressing piece 7012. The pressing piece 7012 is fixed to the upper surface of the disc 701 by bolts.

[0084] Example 8:

[0085] This embodiment shares the same structure as Example 2, except that the photoelastic light source 4 is an LED light strip wrapped around a central fixed column 8. The white light emitted by the photoelastic light source 4 is evenly distributed all around. The power cord for the photoelastic light source 4 is routed from the lower rotor plate of the ring shear apparatus's main structure to ensure it does not interfere with specimen rotation or the chain drive.

[0086] Example 9:

[0087] The main structure of this embodiment is the same as that of Example 2, except that the polarizer 15 of the photoelastic device is a circular polarizer. Double-sided tape and transparent tape are used to affix the two long sides of each polarizer 15 along the inner wall of the inner cylinder 602 and the upper and lower circumferences of the outer wall of the outer cylinder 601, respectively. The polarizer 15 is adhered as closely and flatly to the cylinder wall as possible, leaving as much space as possible at the upper and lower edges for easy viewing.

[0088] Example 10:

[0089] The main structure of this embodiment is the same as that of embodiment 2, wherein the image recording device further includes a ring bracket 10. The camera 11 is suspended on the ring bracket 10.

[0090] Example 11:

[0091] This embodiment provides a test method using the photoelastic testing apparatus based on the ring shear instrument described in Examples 1 to 10. Photoelasticity is used to observe the striations and force chains that appear during the shearing of a granular body. Photoelastic patterns are simultaneously recorded at different times and compared with torque and acoustic emission data to analyze the stresses within and between particles. The test method specifically includes the following steps:

[0092] 1) Check the ring shear instrument, photoelastic device and graphic recording device before use, including checking whether the circuit is normal, whether the motor oil is sufficient, whether the chain drive is smooth, whether the light source is irradiating normally, whether the collected data is normal, etc.

[0093] 2) Let the ring shear instrument run, turn on the LED light strip, and observe whether the sample shows photoelasticity.

[0094] 3) If obvious photoelasticity can be observed under normal operation of the instrument according to steps 1) and 2), the photoelastic image can be recorded.

[0095] 4) Start collecting torque and acoustic emission signals simultaneously.

[0096] 5) Turn on the camera, adjust the height, angle, and field of view clarity one by one, set the shooting frequency, and start capturing images. The interval between each camera starting to shoot is 30 seconds. Record the moment when the first camera starts shooting and takes the first image, which corresponds to a certain moment in the process of torque and acoustic emission signal acquisition.

[0097] 6) After completing a set of experiments, the torque, acoustic emission signals, and captured images must be copied immediately to reserve storage space for subsequent experiments. If the specimen needs to be replaced in subsequent experiments, the power must be turned off before proceeding.

[0098] 7) After the experiment, first confirm that all collected data has been saved and backed up, then turn off the power of each part, remove the camera and place it aside, and disassemble the sample for next use.

Claims

1. A photoelastic testing device based on a ring shear instrument, characterized by: It includes a main structure of a ring shear instrument, a data acquisition device (3), a graphic recording device and a photoelastic device; The main structure of the ring shear instrument comprises a lower movable disc (5), a middle fixed cylinder (6), an upper follower disc (7) and a middle fixed column (8); The lower movable plate (5) includes a support plate I (501), a plurality of columns (503), a rotating cylinder (504) and a gear I (505); the support plate I (501) is placed on the upper surface of the column (503); the support plate I (501) has a coaxially arranged hole (5011) and an annular embedded groove (5012) on its plate surface; the upper end of the rotating cylinder (504) extends out of the hole (5011), and the outer ring of the lower end is provided with a gear I (505); the gear I (505) is connected to the chain (204); The middle fixed cylinder (6) comprises an outer cylinder (601), an inner cylinder (602), an inner fixed disk (603), a rotatable ring at the lower end (604) and a non-rotatable ring at the upper end (605); the outer cylinder (601) and the inner cylinder (602) are made of transparent material; the lower end of the outer cylinder (601) is embedded in the annular embedding groove (5012); the inner cylinder (602) is arranged in the inner cavity of the outer cylinder (601); the outer cylinder (601) and the inner cylinder (602) are coaxially arranged; the inner fixed disk (603) is arranged in the hole (5011); the inner cylinder (602) is placed and fixed on the inner fixed disk (6012). 3) on; the outer cylinder (601) and the inner cylinder (602) enclose a circular cylindrical accommodating space; the upper non-rotatable circular ring (605) and the lower rotatable circular ring (604) are respectively arranged at the upper and lower ends of the circular cylindrical accommodating space; the lower surface of the lower rotatable circular ring (604) is connected to the upper surface of the rotating cylinder (504); the upper surface of the lower rotatable circular ring (604) is provided with serrations; the lower surface of the upper non-rotatable circular ring (605) is provided with serrations; the outer cylinder (601), the inner cylinder (602), the lower rotatable circular ring (604) and the upper non-rotatable circular ring (605) enclose a sample cavity; The upper follower disc (7) is covered on the upper part of the middle fixed cylinder (6); the upper follower disc (7) includes a disc (701) and a raised barrel (702); the disc (701) is fixed on the upper surface of the upper non-rotatable ring (605); the disc (701) blocks the upper end opening of the inner cylinder (602); a plurality of grooves (7011) are provided on the side wall of the disc (701); an acoustic emission probe is arranged in the groove (7011); the lower end of the acoustic emission probe is tightly against the inner cylinder (602); On the upper surface of the non-rotatable ring (605) at the upper end; the raised barrel (702) is a barrel structure with an open lower end and a closed upper end; the raised barrel (702) is arranged on the upper surface of the disc (701); the lower open end of the raised barrel (702) is blocked by the disc (701); a reserved opening (7021) is provided on the side wall of the raised barrel (702); a raised block (7022) is provided on the side wall of the raised barrel (702) next to the reserved opening (7021); The body of the intermediate fixed column (8) sequentially passes through the inner cavity of the rotating cylinder (504), the inner fixed disk (603), the inner cavity of the inner cylinder (602), and the disk (701), and then extends into the inner cavity of the raised barrel (702); the inner fixed disk (603) is fixedly connected to the side wall of the intermediate fixed column (8); The data acquisition device (3) comprises a force sensor (301) and a data acquisition box (302); the handle of the force sensor (301) is detachably mounted on the column body of the middle fixed column (8) after passing through the reserved opening (7021); the body of the force sensor (301) extends to the side of the protruding block (7022); the force sensor (301) is connected to the data acquisition box (302); The graphic recording device includes a plurality of cameras (11); the cameras (11) are arranged around the outside of the central fixed cylinder (6); The photoelastic device comprises a light source (4), a polarizing plate (15), and a photoelastic material sample (16); the light source (4) is arranged on a middle fixed column (8); the polarizing plate (15) is attached to the outer wall of the outer cylinder (601) and the inner wall of the inner cylinder (602); During operation, the sample cavity is filled with a photoelastic material sample (16); the saw teeth of the upper non-rotatable ring (605) and the lower rotatable ring (604) are embedded in the rock and soil sample; the chain (204) drives the rotating cylinder (504) to rotate, and the lower rotatable ring (604) drives the rock and soil sample to rotate, transmitting the torsional force to the upper follower disk (7); the light source (4) irradiates the surroundings, and the photoelastic material sample (16) exhibits a photoelastic phenomenon, and the graphic recording device records the photoelastic image; the force sensor (301) contacts the protruding block (7022) to measure the torsional force, and transmits it to the data acquisition box (302); the photoelastic graphics, torque and acoustic emission data at different times are compared, and the stress inside the particles and between the particles is analyzed.

2. The photoelastic testing device based on a ring shear instrument according to claim 1, characterized in that: The invention also includes a power device (2); the power device (2) includes a distribution box (201), a motor (202), a gear II (203) and a chain (204); the motor (202) is connected to the distribution box (201); the output end of the motor (202) is provided with a gear II (203); the gear II (203) is connected to the chain (204); the distribution box (201) changes the speed of the motor (202) by changing the power provided.

3. The photoelastic testing device based on the ring shear instrument according to claim 1, characterized in that: It also includes a base (1); the lower surface of the base (1) is provided with a rubber sheet.

4. The photoelastic testing device based on a ring shear instrument according to claim 1, characterized in that: The lower movable plate (5) further includes a support plate II (502); the plurality of upright columns (503) are sandwiched between the support plate I (501) and the support plate II (502).

5. The photoelastic testing device based on a ring shear instrument according to claim 1, characterized in that: The outer cylinder (601) and the inner cylinder (602) are both made of a transparent acrylic material; the photoelastic material sample (16) is made of a transparent plastic material; and the photoelastic material sample (16) is in the shape of a disc, a sphere, or a polyhedron.

6. The photoelastic testing device based on a ring shear instrument according to claim 1, characterized in that: The disc (701) also has a pressing sheet (7012); the pressing sheet (7012) is fixed to the upper surface of the disc (701) by means of bolts.

7. The photoelastic testing device based on a ring shear instrument according to claim 1, characterized in that: The light source (4) of the photoelastic device is an LED light strip wound around a middle fixed column (8).

8. The photoelastic testing device based on a ring shear instrument according to claim 1, characterized in that: The polarizer (15) of the photoelastic device is a circular polarizer.

9. The photoelastic testing device based on a ring shear instrument according to claim 1, characterized in that: The graphic recording device further comprises an annular bracket (10); the camera (11) is suspended on the annular bracket (10).

10. A test method using the photoelastic test device based on the ring shear instrument according to claims 1 to 9, characterized in that: Photoelasticity technology is used to observe the stripes and force chains that appear during the shearing process of granular bodies, and the photoelastic patterns at different times are recorded synchronously. The results are compared with the torque and acoustic emission data to analyze the stress inside and between the particles.

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