Control device and experimental method for controlling stress or strain of a test sample

Abstract

The application discloses a control device and experimental method for controlling the loading state of a sample through stress or strain, a device main body of which can be detachably connected with a front-end press machine, and loading force transmission modules, strain control modules, stress control modules and locking modules are arranged on the device main body. The application solves the problem that the sample cannot continue to maintain elastic deformation after being separated from the press machine, and the strain control modules and the stress control modules are arranged to enable the control device to have the functions of strain control and stress control on the loaded sample. The experimental method of the control device can enable the control device to achieve the corresponding load maintaining effect, so that the loaded sample in the control device can still maintain the same loading state as before being separated from the press machine after being separated from the press machine, and thus it is convenient for researchers to monitor the damage of the loaded sample and perform various geophysical signal detection experiments on the loaded sample after being separated from the press machine.

Description

Technical Field

[0001] This invention relates to a control device, and more particularly to a control device and experimental method for controlling the loading state of a specimen through stress or strain, belonging to the research field of mechanical experimental equipment and methods for coal / rock / concrete specimens. Background Technology

[0002] With the rapid development of underground engineering, the problems faced in underground engineering construction, such as the stability of coal and rock masses and concrete structures, are becoming increasingly complex. There is an urgent need to study the evolution of microcracks in coal and rock masses and concrete under external loads, from initiation and propagation to penetration and instability, and to investigate the geophysical monitoring signal characteristics during the instability process. Therefore, achieving damage monitoring and geophysical signal detection under in-situ loading conditions is particularly important. However, due to limitations in equipment space and cost, it is difficult to conduct damage and various geophysical signal detection experiments under in-situ loading conditions on the specimens. Inventing a loading condition that can be detached from the press while maintaining the specimen in-situ loading state is an effective measure to achieve this research.

[0003] To address the above problems, this invention provides a control device and experimental method for controlling the loading state of a specimen through stress or strain, so that the specimen can maintain a specific load after being removed from the press, and can be used for subsequent damage monitoring and various geophysical signal detection experiments. Summary of the Invention

[0004] To address the shortcomings of the aforementioned technologies, this invention provides a control device and experimental method for controlling the loading state of a specimen through stress or strain.

[0005] A control device for controlling the loading state of a specimen by stress or strain, comprising:

[0006] The main body of the device can be assembled and disassembled with the front-end press, and it is equipped with a loading force transmission module, a strain control module, a stress control module, and a locking module.

[0007] The loading force transmission module applies static pressure to the loaded specimen located in the main body of the device through a locking module that abuts against it at its upper part, so as to lock their respective positions and prevent displacement. At the same time, the stress control module that is in contact with the loaded specimen tests, reads and records the specific stress loading data of the loaded specimen at different stages of the experiment. The upper part of the locking module is also equipped with a strain control module that can be adjusted to abut against it. The displacement of the loaded specimen when the strain control module is in contact with the locking module can be calculated by the reading of the strain control module.

[0008] Furthermore, the main body of the device includes an inner shell that can hold the loaded specimen and an outer shell that supports the strain control module.

[0009] The bottom of the main body shell is embedded with a flat plate stress sensor that abuts against the loaded sample. The center of the flat plate stress sensor has a first shearing die slot that can fix the front shearing die. The bottom of the main body shell is also provided with a fixing slot that faces outward and is convenient to be installed with the front press.

[0010] The main body shell has a cylinder forming in the middle that connects its inner and outer sides in the vertical direction.

[0011] Furthermore, the loading force transmission module includes an upper pressure head, a pressure head connecting rod, and a lower pressure head integrally formed from top to bottom. The upper and lower pressure heads are arranged parallel to each other and are both perpendicular to the pressure head connecting rod. The top center of the upper pressure head has an upward protruding fixed protrusion that cooperates with the fixing slot to install the front-end press. The lower pressure head has a second shearing mold slot in the middle of its lower surface that contacts the loaded sample. The pressure head connecting rod is sleeved in the cylinder and can reciprocate with the cylinder axis under the action of the front-end press.

[0012] Furthermore, multiple strain control modules are arranged around the radial periphery of the cylinder. Each strain control module includes a fixed bracket fixed to the main body shell. A displacement fine-tuning screw is arranged in the center of the fixed bracket and passes through it vertically. A displacement adjustment micro-cylinder that can display displacement data is fixedly connected to the part of the displacement adjustment screw located outside the fixed bracket. A displacement adjustment locking device is also provided on the main body shell to lock and limit the displacement of the displacement adjustment micro-cylinder and the displacement fine-tuning screw.

[0013] Furthermore, the locking module includes a locking screw located directly below the displacement fine-tuning screw. The locking screw extends from the fixed bracket into the main body housing. A locking nut is also provided at the top of the locking screw. By adjusting the locking nut, the lower end of the locking screw can abut against the upper surface of the lower pressure head and apply pressure to compress the loaded sample.

[0014] Furthermore, the upper and lower positions of the first shearing die slot and the second shearing die slot correspond to each other, and the shearing die is simultaneously fixed / removed on both to conduct shearing mechanics tests on the loaded specimen.

[0015] The experimental method for controlling the loading state of a specimen using a control device based on stress or strain, and the specific operating steps of the experimental method are as follows:

[0016] S1. Assemble the control device containing the loaded sample with the press;

[0017] S2. Adjust the locking module and adjust the strain control module accordingly;

[0018] S3. Start the front-end pressure machine, load it to the specified experimental load (load / displacement) and maintain the load;

[0019] S4. Adjust the control device according to the readings of the stress control module and strain control module until the load is maintained;

[0020] S5. Unload the press;

[0021] S6. Conduct subsequent damage monitoring and various geophysical signal detection experiments together with the control device and the loaded sample.

[0022] Furthermore, in S2:

[0023] First, apply external force to the locking module to compress the loaded specimen through the load transmission module, read the data from the stress control module and adjust the loaded specimen to reach the initial loading state.

[0024] In this process, the locking nut is adjusted downwards to apply pressure to the lower pressure head by the locking screw until the loaded specimen is compressed;

[0025] Next, adjust the strain control module to abut and lock the locking module, and then read the strain control module reading x1;

[0026] The process involves adjusting the displacement adjusting micro-cylinder so that the lower end of the displacement fine-tuning screw abuts against the locking nut, and then locking the displacement adjusting micro-cylinder and the displacement fine-tuning screw using the displacement adjusting locking device, before reading the displacement adjusting micro-cylinder's reading x1.

[0027] Further, in S4, the locking module and strain control module are adjusted sequentially until the reading of the strain control module x2 = the strain of the sample + x1 and the reading of the stress control module equals the holding load of the front press.

[0028] This invention discloses a control device and experimental method for controlling the loading state of a specimen through stress or strain. It solves the problem that the specimen cannot maintain elastic deformation after being removed from the press. Furthermore, by setting up strain control module and stress control module, the control device has the function of strain control and stress control of the loaded specimen. The experimental method of the control device enables the control device to achieve its corresponding load-preserving effect, so that the loaded specimen in the control device still maintains the same loading state as before being removed from the press. This facilitates researchers to conduct damage monitoring and various geophysical signal detection experiments on the loaded specimen after it is removed from the press. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0030] Figure 2 This is a schematic diagram of the main body of the device of the present invention.

[0031] Figure 3This is a schematic diagram of the loading and force transmission module of the present invention.

[0032] Figure 4 This is a schematic diagram of the strain control module of the present invention.

[0033] Figure 5 This is a schematic diagram of the stress control module and locking module of the present invention.

[0034] Figure 6 This is a flowchart of the experimental method of the present invention.

[0035] In the figure: 1. Main body of the device; 10. Main body shell; 11. Fixing slot; 12. Cylinder; 2. Loading force transmission module; 20. Fixing protrusion; 21. Upper pressure head; 22. Pressure head connecting rod; 23. Lower pressure head; 3. Strain control module; 30. Displacement adjustment micro-cylinder; 31. Displacement adjustment locking device; 32. Displacement fine-tuning screw; 33. Fixing bracket; 4. Stress control module; 40. Flat plate stress sensor; 5. Locking module; 50. Locking nut; 51. Locking screw; 6. Loaded specimen; 7. First shearing die slot; 8. Second shearing die slot. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0037] The control device for controlling the loading state of a specimen by stress or strain includes a main body 1, which can be assembled and disassembled with a front-end press, and is equipped with a loading force transmission module 2, a strain control module 3, a stress control module 4, and a locking module 5.

[0038] Among them, reference Figure 1-2 As shown, the main body 1 of the device includes a main shell 10 on the outside, which can hold the loaded sample 6 and supports the strain control module 3. The bottom of the main shell 10 is embedded with a flat plate stress sensor 40 that abuts against the loaded sample 6. The center of the flat plate stress sensor 40 is formed with a first shearing mold slot 7 that can fix the front shearing mold. The bottom of the main shell 10 is also provided with a fixing slot 11 that faces outward and is convenient for installation with the front press. In addition, a cylinder 12 is formed in the middle of the main shell 10, which connects the inner and outer sides in the vertical direction.

[0039] refer to Figure 1-3 As shown, the loading force transmission module 2 penetrates both the inner and outer sides of the main body 1 of the device, and applies pressure to the loaded sample 6 located in the main body 1 of the device under the external force of the front-end press. Specifically, regarding its penetration through both the inner and outer sides of the main body 1 of the device:

[0040] The loading force transmission module 2 includes an upper pressure head 21, a pressure head connecting rod 22, and a lower pressure head 23 integrally formed from top to bottom. The upper pressure head 21 and the lower pressure head 23 are arranged parallel to each other and are both perpendicular to the pressure head connecting rod 22. The pressure head connecting rod 22 is sleeved inside the cylinder 12. The upper pressure head 21 is located outside the main body 1 of the device, or in other words, it can be understood that the upper pressure head 21 is located outside the main body shell 10. Then, the lower pressure head 23 is located inside the main body shell 10. Thus, the loading force transmission module 2 actually forms a connection relationship that runs through and connects the inner and outer sides of the main body 1 of the device.

[0041] Furthermore, a fixed protrusion 20 is formed at the top center of the upper pressure head 21, which protrudes upward and is fitted with the fixed slot 11 to be installed with the front press. In this way, the control device disclosed in this invention can be firmly installed on the front press and effectively prevents the control device from moving horizontally on the press. Next, a second shearing mold slot 8 is formed at the center of the lower surface of the lower pressure head 23 that contacts the loaded sample 6. It can be fitted with the first shearing mold slot 7 to fix the front shearing mold. Thus, when the press applies pressure downward or releases pressure, the integrally formed upper pressure head 21, pressure head connecting rod 22, and lower pressure head 23 transmit pressure in sequence and form a reciprocating motion with the axial direction of the cylinder 12.

[0042] Based on the above structure, the upper and lower positions of the first shearing die slot 7 and the second shearing die slot 8 correspond to each other, and the shearing die is fixed / removed simultaneously on both to conduct shearing mechanical tests on the loaded specimen 6.

[0043] like Figure 1 and Figure 4 The strain control module 3, as shown, monitors the displacement data of the loaded specimen 6 in conjunction with the locking module 5 when the specimen 6 is deformed under load. Furthermore, it adjusts the strain control module 3 according to the experimental conditions of the loaded specimen 6 at different stages. Specifically:

[0044] Multiple strain control modules 3 are arranged radially around the cylinder 12. Each strain control module 3 includes a fixed bracket 33 fixed to the main body shell 10. A displacement fine-tuning screw 32 is arranged in the center of the fixed bracket 33 and passes through it vertically. A displacement adjustment micro-cylinder 30 that can display displacement data is fixedly connected to the part of the displacement adjustment screw 32 located outside the fixed bracket 33. A displacement adjustment locking device 31 is also provided on the main body shell 10 to lock and limit the displacement of the displacement adjustment micro-cylinder 30 and the displacement fine-tuning screw 32. Through the arrangement of the strain control modules 3, this control device has the technical effect of monitoring the displacement data of the loaded sample 6.

[0045] The stress control module 4 tests, records, and reads the specific stress loading data of the loaded specimen 6 at different stages. It monitors the loaded specimen 6 through the flat plate stress sensor 40, enabling the control device to have stress control characteristics.

[0046] Locking module 5 provides stress control and anti-displacement locking control for loading force transmission module 2 and loaded specimen 6. Specifically:

[0047] The locking module 5 includes a locking screw 51 located directly below the displacement fine-tuning screw 32. The locking screw 51 extends from the fixed bracket 33 into the main body housing 10. A locking nut 50 is also provided at the top of the locking screw 51. By adjusting the locking nut 50, the lower end of the locking screw 51 can abut against the upper surface of the lower pressure head 23 and apply pressure to press the loaded sample 6.

[0048] The experimental method for controlling the loading state of a specimen by stress or strain using a control device is as follows:

[0049] S1. Assemble the control device with the loaded sample (6) placed on it with the press;

[0050] S2. Adjust the locking module (5) and adjust the strain control module (3) accordingly;

[0051] S3. Start the front-end pressure machine, load it to the specified experimental load (load / displacement) and maintain the load;

[0052] S4. Adjust the control device according to the readings of the stress control module (4) and the strain control module (3) until the load is maintained;

[0053] S5. Unload the press;

[0054] S6. The control device, together with the loaded sample (6), is used for subsequent damage monitoring and detection of various geophysical signals.

[0055] It should be noted that in S2, firstly, an external force is applied to the locking module 5 to press the loaded specimen 6 through the loading force transmission module 2, the data of the stress control module 4 is read, and the loaded specimen 6 is adjusted to reach the initial loading state. Specifically, this is achieved by adjusting the locking nut 50 downward so that the locking screw 51 applies pressure to the lower pressure head 23 until the loaded specimen 6 is pressed. Secondly, the strain control module 3 is adjusted so that it abuts against and locks the locking module 5. Then, the reading x1 of the strain control module 3 is read. Specifically, the displacement adjustment micro-cylinder 30 is adjusted so that the lower end of the displacement fine-tuning screw 32 abuts against the locking nut 50, and the displacement adjustment micro-cylinder 30 and the displacement fine-tuning screw 32 are locked by the displacement adjustment locking device 31. Then, the reading x1 of the displacement adjustment micro-cylinder 30 is read.

[0056] Next, in S4, adjust the locking module 5 and strain control module 3 in sequence until the reading x2 of strain control module 3 equals the strain of the sample + x1 and the reading of stress control module 4 equals the holding load of the front press.

[0057] Thus, the control device and experimental method disclosed in this invention, which controls the loading state of a specimen by stress or strain, solves the problem that the specimen cannot maintain elastic deformation after being removed from the press. Furthermore, the strain control module 3 and stress control module 4 enable the control device to perform strain and stress control on the loaded specimen. The experimental method of the control device allows it to achieve its corresponding load-preserving effect, ensuring that the loaded specimen inside the control device maintains the same loading state as before being removed from the press. This facilitates damage monitoring and various geophysical signal detection experiments on the loaded specimen after removal from the press.

[0058] The above embodiments are not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solution of the present invention are also within the protection scope of the present invention.

Claims

1. A control device for controlling the loading state of a specimen by stress or strain, characterized in that it include: The main body of the device (1) is connected to the front-end press for loading and unloading, and is equipped with a loading force transmission module (2), a strain control module (3), a stress control module (4), and a locking module (5). The loading force transmission module (2) applies static pressure to the loaded specimen (6) located in the main body (1) of the device through the locking module (5) which abuts against it on its upper part, so as to lock their respective positions and prevent displacement. At the same time, the stress control module (4) which is in contact with the loaded specimen (6) tests, reads and records the specific stress loading data of the loaded specimen (6) at different stages of the experiment. The upper part of the locking module (5) is also provided with a strain control module (3) which can be adjusted to abut against it. The displacement of the loaded specimen (6) can be calculated by the reading of the strain control module (3) when the strain control module (3) and the locking module (5) are in contact. The main body (1) of the device includes an inner shell (10) on which a loaded specimen (6) can be placed and an outer shell (10) on which a strain control module (3) is provided. The bottom of the main body shell (10) is embedded with a flat plate stress sensor (40) that abuts against the loaded sample (6). The center of the flat plate stress sensor (40) is formed with a first shearing mold slot (7) for fixing the front shearing mold. The bottom of the main body shell (10) is also provided with a fixing slot (11) that faces outward and is convenient to be installed with the front press. The main body shell (10) has a cylinder (12) formed in the middle, which connects its inner and outer sides in the vertical direction. The cylinder (12) is surrounded by multiple strain control modules (3) in the radial direction. The strain control module (3) includes a fixed bracket (33) fixed on the main body shell (10). A displacement fine-tuning screw (32) is provided in the center of the fixed bracket (33) and passes through it in the vertical direction. A displacement adjustment micro cylinder (30) that can display displacement data is fixedly connected to the part of the displacement adjustment screw (32) located outside the fixed bracket (33). A displacement adjustment locking device (31) that can lock and limit the displacement of the displacement adjustment micro cylinder (30) and the displacement fine-tuning screw (32) is also provided on the main body shell (10).

2. The control device for controlling the loading state of a specimen by stress or strain according to claim 1, characterized in that: The loading force transmission module (2) includes an upper pressure head (21), a pressure head connecting rod (22), and a lower pressure head (23) integrally formed from top to bottom. The upper pressure head (21) and the lower pressure head (23) are arranged parallel to each other and are perpendicular to the pressure head connecting rod (22). The upper pressure head (21) has a fixed protrusion (20) that protrudes upward and is fitted with a fixing slot (11) to be installed with the front-end press. The lower pressure head (23) has a second shearing mold slot (8) in the middle of its lower surface that contacts the loaded sample (6), which can be fitted with the first shearing mold slot (7) to fix the front-end shearing mold. The pressure head connecting rod (22) is sleeved in the cylinder (12) and can reciprocate with the cylinder (12) under the action of the front-end press.

3. The control device for controlling the loading state of a specimen by stress or strain according to claim 2, characterized in that: The locking module (5) includes a locking screw (51) located directly below the displacement fine-tuning screw (32). The locking screw (51) extends from the fixed bracket (33) into the main body shell (10). The top of the locking screw (51) is also provided with a locking nut (50). By adjusting the locking nut (50), the lower end of the locking screw (51) can be made to abut against the upper surface of the lower pressure head (23) and apply pressure to press the loaded sample (6).

4. The control device for controlling the loading state of a specimen by stress or strain according to claim 2, characterized in that: The first shearing die slot (7) and the second shearing die slot (8) are positioned vertically to each other, and the shearing die is fixed / removed simultaneously to conduct shearing mechanical tests on the loaded specimen (6).

5. The experimental method of the control device for controlling the loading state of a specimen by stress or strain according to any one of claims 1-4, characterized in that, The specific operational steps of the experimental method are as follows: S1. Assemble the control device with the loaded sample (6) on it and the press. S2. Adjust the locking module (5) and adjust the strain control module (3) accordingly; S3. Start the front-end pressure machine, load it to the specified experimental load (load / displacement) and maintain the load; S4. Adjust the control device according to the readings of the stress control module (4) and the strain control module (3) until the load is maintained; S5. Unload the press; S6. The control device, together with the loaded sample (6), is used for subsequent damage monitoring and detection of various geophysical signals.

6. The experimental method of the control device for controlling the loading state of a specimen by stress or strain according to claim 5, characterized in that, In S2: First, apply external force to the locking module (5) to press the loaded specimen (6) through the loading force transmission module (2), read the data of the stress control module (4) and adjust the loaded specimen (6) to reach the initial loading state; In this process, the locking nut (50) is adjusted downwards to apply pressure to the lower pressure head (23) by the locking screw (51) until the loaded specimen (6) is pressed tightly. Next, adjust the strain control module (3) to abut and lock the locking module (5), and then read the reading x1 of the strain control module (3); Among them, the displacement adjusting micro cylinder (30) is adjusted so that the lower end of the displacement fine-tuning screw (32) abuts against the locking nut (50), and the displacement adjusting micro cylinder (30) and the displacement fine-tuning screw (32) are locked by the displacement adjusting locking device (31), and the reading x1 of the displacement adjusting micro cylinder (30) is read.

7. The experimental method of the control device for controlling the loading state of a specimen by stress or strain according to claim 6, characterized in that: In S4, the locking module (5) and the strain control module (3) are adjusted in sequence until the reading of the strain control module (3) x2 = the strain of the sample + x1 and the reading of the stress control module (4) equals the holding load of the front press.

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