Brittle material compression test device and method assisted by crfp-magnetorheological elastomer

Abstract

The brittle material compression test device and method assisted by CFRP-magnetorheological elastomer loading, the device comprises: a load frame, a support mechanism, a pressure mechanism and a data acquisition and processing mechanism; the load frame is divided into upper and lower two layers, the upper layer is used for placing the sample, the lower layer is provided with the pressure mechanism, and the pressure mechanism applies axial pressure to the sample from below; the data acquisition and processing mechanism comprises: a load sensor, a displacement sensor and a controller, the load sensor is installed at the top of the sample to measure the axial pressure, the displacement sensor is arranged on the side of the sample to measure the strain, and the controller draws a stress-strain curve according to the axial pressure and the strain; two support mechanisms are arranged on the two sides of the sample, and the support mechanism comprises a CFRP column core and a magnetorheological elastomer arranged outside the CFRP column core, a coil is arranged outside the magnetorheological elastomer, and the controller is used for controlling the coil to be electrified. The device can rapidly adjust the pressure of the sample, the stress-strain curve measured by the device is accurate, the structure is simple, and the device is convenient to operate.

Description

Technical Field

[0001] This invention belongs to the technical field of hydraulic material testing machines, and relates to a device and method for compression testing of brittle materials with CFRP-magnetorheological elastomer assisted loading. Background Technology

[0002] When determining the compressive stress-strain curve of rock materials, a conventional hydraulic material testing machine is typically used. While conventional hydraulic presses can accurately measure the rising segment of the curve, their insufficient rigidity leads to significant stress after loading. During loading, the specimen deforms, and the machine frame stretches under tension, accumulating a large amount of elastic strain energy. After reaching the peak of the stress-strain curve, the material's load-bearing capacity decreases, and the machine recovers its deformation due to the reduced force. If the machine's rebound deformation exceeds the deformation required for specimen failure, the specimen deforms and breaks rapidly, resulting in an irregular curve after the peak point. Traditional material compression testing machines can roughly produce stress-strain curves for relatively stiff rock materials. Figure 6 Indication.

[0003] To more accurately measure the complete stress-strain curve of a specimen, two traditional methods exist: one is to increase the stiffness of the testing machine to reduce springback deformation after reaching the peak value. However, this method requires highly stiff components, which are difficult to design and manufacture, and is also too expensive. The other method involves installing a strain sensor on the specimen, using the sensor's signal to control the oil pump's oil inlet and outlet. This method consumes a lot of electricity and is costly. Another method involves placing a jack between the upper and lower pressure plates of the testing machine to control the oil flow in and out of both the machine and the jack, thus obtaining the test results. However, this method is highly dependent on the oil flow, complex to operate, has a significant delay in oil flow control, and is prone to large errors. Therefore, there is an urgent need for a testing machine that is low-cost, simple to manufacture, and capable of accurately measuring stress and strain. Summary of the Invention

[0004] The purpose of this invention is to provide a CFRP-magnetorheological elastomer-assisted loading device and method for compressive testing of brittle materials, in order to solve the problem that existing ordinary hydraulic material testing machines cannot measure the complete stress-strain curve of rock masses with large stiffness.

[0005] This invention provides a CFRP-magnetorheological elastomer-assisted loading compression testing device for brittle materials, comprising: a load frame, a support mechanism, a pressure mechanism, and a data acquisition and processing mechanism; the load frame is divided into upper and lower layers, the upper layer for placing the specimen, and the lower layer for installing the pressure mechanism, which applies axial pressure to the specimen from below; the data acquisition and processing mechanism includes: a load sensor, a displacement sensor, and a controller, the load sensor being installed on the top of the specimen to measure the axial pressure applied by the pressure mechanism, the displacement sensor being located on the side of the specimen to measure the strain of the specimen, and the controller plotting stress-strain curves based on the axial pressure and strain; the device has two support mechanisms, which are located on the upper layer of the load frame and symmetrically arranged on both sides of the specimen, each support mechanism including a CFRP core, a magnetorheological elastomer, coils, and lead cylinders, the magnetorheological elastomer being wrapped around the CFRP core, multiple layers of coils being wound around the magnetorheological elastomer, and lead cylinders being placed between adjacent layers of coils, the controller controlling the coils to be energized or de-energized.

[0006] In the CFRP-magnetorheological elastomer-assisted loading brittle material compression testing device of the present invention, the load frame includes: a lower crossbeam, a pressure plate, an upper crossbeam, an upper column, and a lower column; two lower columns are provided on the lower crossbeam, and an upper column is provided on the lower column, with the top of the upper column fixed to the bottom surface of the upper crossbeam; the diameter of the upper column is smaller than the diameter of the lower column; two through holes are provided on the pressure plate, through which the two upper columns pass; the bottom surface of the pressure plate is supported on the top of the lower column and can move up and down along the upper column; gaskets are provided on the bottom surface of the upper crossbeam and the top surface of the lower crossbeam; a load sensor is installed on the top of the sample and then the entire sample is installed between the two gaskets; two cylindrical blocks are provided on the bottom surface of the upper crossbeam, and the support mechanism is located between the pressure plate and the cylindrical blocks; the pressure mechanism is located on the lower crossbeam, and the pressure mechanism applies axial pressure to the sample through the transmission of the pressure plate.

[0007] In the CFRP-magnetorheological elastomer-assisted loading brittle material compression test device of the present invention, the support mechanism is a cylindrical structure, the outer diameter of the magnetorheological elastomer is smaller than the inner diameter of the innermost coil and a space of 0.5 cm is left to accommodate the lateral expansion caused by the vertical compression of the magnetorheological elastomer, and a beryllium bronze alloy shell is wrapped around the outermost coil to reduce magnetic field diffusion.

[0008] In the CFRP-magnetorheological elastomer-assisted loading brittle material compression test apparatus of the present invention, the diameter of the cylindrical pad is larger than the outer diameter of the magnetorheological elastomer and smaller than the inner diameter of the innermost coil. The central axis of the cylindrical pad is on the same straight line as the central axis of the magnetorheological elastomer. Before applying axial pressure, the cylindrical pad is in contact with the magnetorheological elastomer. During the compression of the specimen, the cylindrical pad can be inserted into the innermost coil to compress the sandwich column composed of CFRP and magnetorheological elastomer.

[0009] In the CFRP-magnetorheological elastomer-assisted loading brittle material compression test device of the present invention, the pressure mechanism is a hydraulic cylinder, and the oil inlet and outlet of the hydraulic cylinder are controlled by a controller.

[0010] In the CFRP-magnetorheological elastomer-assisted loading brittle material compression testing apparatus of the present invention, the upper crossbeam, pressure plate, lower crossbeam, upper column, lower column, cylindrical pad, and gasket are all made of antimagnetic stainless steel with a magnetic permeability of 1.001–1.01 H / m, a Young's modulus of 200 GPa, and a density of 7.7 g / cm³. 3 .

[0011] In the CFRP-magnetorheological elastomer-assisted loading brittle material compression testing apparatus of the present invention, the CFRP core is a high-performance composite material formed by pultrusion, winding, and compression molding processes using carbon fiber as reinforcement and resin as matrix; the carbon fiber is prepared from organic fibers through high-temperature carbonization and graphitization, with a density of 1.8 g / cm³. 3 It is a microcrystalline graphite material with a carbon content of over 90%.

[0012] In the CFRP-magnetorheological elastomer-assisted loading brittle material compression test device of the present invention, the preparation process of the magnetorheological elastomer is as follows: rubber matrix, magnetic particles and all filler materials are put into a rubber mixing mill, mechanically stirred evenly and then placed in a vacuum barrel at high temperature for degassing, and then injected into an aluminum mold; vulcanizing agent and vulcanization accelerator are poured into the mold and vulcanized at high temperature, and an anisotropic cylindrical magnetorheological elastomer is prepared by applying a magnetic field during vulcanization.

[0013] This invention provides a method for compression testing of brittle materials using CFRP-magnetorheological elastomer-assisted loading, comprising:

[0014] (1) Prepare several rock samples of the same size and composition; install the samples, load sensors, and displacement sensors, and connect the hydraulic cylinder pump and each sensor to the controller.

[0015] (2) Begin applying pressure with the coil de-energized until the specimen fails, and record the peak pressure N collected by the load cell. f Input to the controller;

[0016] (3) When a new specimen is placed in the pressure, the coil is not energized in the early stage of the stress-strain curve rise. The stiffness of the magnetorheological elastomer is low and the elasticity is strong.

[0017] (4) When the specimen pressure reaches 0.8N fAt this time, the controller controls the supply of power to the coil, generating a magnetic field with a magnetic induction intensity of 2T, which increases the stiffness of the magnetorheological elastomer and the stiffness of the CFRP-magnetorheological elastomer sandwich column.

[0018] (5) When the specimen reaches the ultimate bearing capacity, the bearing capacity begins to decrease. Due to the support of the sandwich column, the pressure borne by the specimen is reduced, which prevents the test machine from rebounding. During this process, the hydraulic cylinder continuously injects oil to pressurize.

[0019] (6) In the later part of the descending segment of the stress-strain curve, the specimen's load-bearing capacity decreases only slightly. When the specimen's load-bearing capacity drops to 0.3 N... f At the same time, the magnitude of the current is adjusted, and the magnetic induction intensity of the magnetic field is controlled between 0.8T and 1.2T to reduce the stiffness of the magnetorheological elastic body and increase the strain rate.

[0020] (7) The controller calculates and processes the data collected by each sensor, and finally obtains the complete stress-strain curve, which is then displayed on the screen.

[0021] The CFRP-magnetorheological elastomer-assisted loading compression testing apparatus and method for brittle materials of the present invention have at least the following beneficial effects:

[0022] 1. The rigidity requirements of the test device are not high, the production process requirements are low, and the complete stress-strain curve of rock mass material with a stiffness greater than that of the test device can be measured without adding extra rigidity to the test device.

[0023] 2. The present invention unloads the sample pressure by controlling the strength of the magnetorheological elastomer through an energized coil. The strength change rate is on the order of milliseconds. Compared with the traditional method of controlling the sample pressure by adjusting the oil inlet and outlet of a hydraulic press or jack, the adjustment rate is not on the same order of magnitude and is much faster. The present invention can adjust the pressure of the material more quickly and the measured stress-strain curve is more accurate.

[0024] 3. The strength change of the magnetorheological elastomer is the main control variable, and the strength of the magnetorheological elastomer is controlled by the controller coil current. Therefore, the requirements for the oil inlet rate control of the test device are low, which reduces the difficulty of operation. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the CFRP-magnetorheological elastomer-assisted loading brittle material compression testing device of the present invention;

[0026] Figure 2 This is a cross-sectional view of the CFRP-magnetorheological elastomer-assisted loading brittle material compression testing apparatus of the present invention;

[0027] Figure 3 It is a cross-sectional view of the support mechanism;

[0028] Figure 4 These are the coil current curve and the stress-strain curve;

[0029] Figure 5 It is a graph showing the relationship between the axial pressure on the sample and the total pressure of the hydraulic cylinder and the axial displacement.

[0030] Figure 6 It is the stress-strain curve of rock material measured by a traditional material compression testing machine;

[0031] Among them: 11-upper crossbeam, 12-lower crossbeam, 13-cylindrical pad, 14-upper column, 15-pressure plate, 16-shield, 17-hydraulic cylinder, 18-oil pump, 19-lower column, 2-support mechanism, 21-CFRP core, 22-magnetorheological elastomer, 23-coil, 24-lead cylinder, 25-beryllium bronze alloy shell, 31-load sensor, 32-displacement sensor, 33-display screen, 34-controller. Detailed Implementation

[0032] like Figure 1 and 2 As shown, the CFRP-magnetorheological elastomer-assisted loading brittle material compression testing device of the present invention includes: a load frame, a support mechanism 2, a pressure mechanism, and a data acquisition and processing mechanism. The load frame is divided into upper and lower layers. The upper layer is used to place the specimen 4, and the lower layer is used to install the pressure mechanism, which applies axial pressure to the specimen 4 from below. The data acquisition and processing mechanism includes: a load sensor 31, a displacement sensor 32, and a controller 34. The load sensor 31 is installed on the top of the specimen 4 to measure the axial pressure applied by the pressure mechanism, the displacement sensor 32 is located on the side of the specimen 4 to measure the strain of the specimen, and the controller 34 plots stress-strain curves based on the axial pressure and strain. The device is equipped with two support mechanisms 2, which are set on the upper layer of the load frame and symmetrically arranged on both sides of the sample 4. The support mechanism 2 includes a CFRP core 21, a magnetorheological elastomer 22, a coil 23 and a lead tube 24. The magnetorheological elastomer 22 is wrapped around the CFRP core 21. Multiple layers of coil 23 are wound around the outside of the magnetorheological elastomer 22. A lead tube 24 is set between two adjacent layers of coil 23. The coil 23 is energized or de-energized by a controller 34.

[0033] The load frame includes: a lower crossbeam 12, a pressure plate 15, an upper crossbeam 11, an upper column 14, and a lower column 19. Two lower columns 19 are mounted on the lower crossbeam 12, and an upper column 14 is mounted on each lower column 19. The top of the upper column 14 is fixed to the bottom surface of the upper crossbeam 11. The diameter of the upper column 14 is smaller than the diameter of the lower column 19. The pressure plate 15 has two through holes through which the two upper columns 14 pass. The bottom surface of the pressure plate 15 is supported on the top of the lower column 19 and can move up and down along the upper column 14. Gaskets 16 are provided on the bottom surface of the upper crossbeam 11 and the top surface of the lower crossbeam 12. The load sensor 31 is installed on the top of the sample 4 and then the entire sample is installed between the two gaskets 16. Two cylindrical blocks 13 are provided on the bottom surface of the upper crossbeam 11, and the support mechanism 2 is located between the pressure plate 15 and the cylindrical blocks 13. The pressure mechanism is mounted on the lower crossbeam 12, and the pressure mechanism applies axial pressure to the sample 4 through the transmission of pressure plate 15.

[0034] like Figure 3 As shown, the support mechanism 2 is a cylindrical structure. The outer diameter of the magnetorheological elastomer 22 is smaller than the inner diameter of the innermost coil 23 and leaves a space of 0.5cm to accommodate the lateral expansion caused by the vertical compression of the magnetorheological elastomer. The outermost coil 23 is wrapped with a beryllium bronze alloy shell 25 to reduce magnetic field diffusion.

[0035] The diameter of the cylindrical pad 13 is slightly larger than the outer diameter of the magnetorheological elastomer 22, and the central axis of the cylindrical pad 13 is collinear with the central axis of the magnetorheological elastomer 22. Before applying axial pressure, the cylindrical pad 13 is in contact with the magnetorheological elastomer 22. During the compression of the specimen 4, the cylindrical pad 13 can be inserted into the coil 23 to compress the sandwich column formed by the CFRP core 21 and the magnetorheological elastomer 22.

[0036] In practice, the radius of the CFRP core 21 is 3cm, and the outer diameter of the magnetorheological elastomer 22 is 10cm. The thickness of each lead cylinder 24 is 2mm, and the thickness of the beryllium bronze alloy outer shell 25 is 3mm.

[0037] In practice, the pressure mechanism is a hydraulic cylinder 17, and the oil inlet and outlet of the hydraulic cylinder are controlled by a controller 34.

[0038] In specific implementation, the upper crossbeam 11, pressure plate 15, lower crossbeam 12, upper column 14, lower column 19, cylindrical pad 13, and gasket 16 are all made of antimagnetic stainless steel, with a magnetic permeability of 1.001~1.01H / m, a Young's modulus of 200GPa, and a density of 7.7g / cm³. 3 .

[0039] In practice, the data acquisition and processing mechanism also includes a display 33 for displaying the data detected by the sensor and the stress-strain curve.

[0040] In specific implementation, the CFRP core is a high-performance composite material formed by bonding carbon fiber as the reinforcement and resin as the matrix through pultrusion, winding, and compression molding processes; the carbon fiber is prepared from organic fibers through high-temperature carbonization and graphitization, with a density of 1.8 g / cm³. 3 It is a microcrystalline graphite material with a carbon content of over 90%.

[0041] In specific implementation, the preparation process of the magnetorheological elastomer is as follows: A rubber matrix, magnetic particles, and all fillers are placed in a rubber mixing mill, mechanically stirred uniformly, and then placed in a high-temperature vacuum chamber for degassing. The mixture is then injected into an aluminum mold. A vulcanizing agent and vulcanization accelerator are poured into the mold and vulcanized at high temperature. A magnetic field is applied during vulcanization to prepare an anisotropic cylindrical magnetorheological elastomer. The magnetic particles used in the magnetorheological elastomer of this invention are hydroxyl iron powder, with a particle volume fraction of 45%.

[0042] In practice, the test specimen is a cylindrical rock specimen with a radius of 3 cm and a height of 6 cm.

[0043] The CFRP-magnetorheological elastomer-assisted loading method for compressive testing of brittle materials of the present invention includes the following steps:

[0044] (1) Prepare several rock samples with the same size and composition; install sample 4, load sensor 31, displacement sensor 32, and connect the oil pump 18 of hydraulic cylinder 17 and each sensor to controller 34.

[0045] (2) Begin applying pressure without energizing coil 23 until the specimen breaks, and record the peak pressure N collected by load sensor 31. f Input to controller 34;

[0046] (3) When a new specimen is placed in the test piece and pressure is applied, the coil is not energized in the early stage of the stress-strain curve rise. The stiffness of the magnetorheological elastomer 22 is low and the elasticity is strong.

[0047] (4) When the specimen pressure reaches 0.8N f At this time, the controller 34 controls the power supply to the coil 23, generating a magnetic field with a magnetic induction intensity of 2T, which increases the stiffness of the magnetorheological elastomer and the stiffness of the CFRP-magnetorheological elastomer sandwich column.

[0048] (5) When the specimen reaches the ultimate bearing capacity, the bearing capacity begins to decrease. Due to the support of the sandwich column, the pressure borne by the specimen is reduced, which prevents the test device from rebounding. During this process, the hydraulic cylinder continuously injects oil to pressurize.

[0049] (6) In the later part of the descending segment of the stress-strain curve, the specimen's bearing capacity decreases only slightly, while the pressure on the sandwich column increases too rapidly. When the specimen's bearing capacity drops to 0.3 N... f At that time, the coil current is adjusted, and the magnetic induction intensity of the magnetic field is controlled between 0.8T and 1.2T to reduce the stiffness of the magnetorheological elastomer and increase the strain rate.

[0050] (7) The controller calculates and processes the data collected by each sensor, and finally obtains the complete stress-strain curve, which is then displayed on the screen.

[0051] The magnetic field strength control process of this invention:

[0052] The variable controlled in this invention is the stiffness of the CFRP-magnetorheological elastomer sandwich column, which is adjusted by controlling the magnetic field strength. The stiffness control is based on the change in the load-bearing pressure of the specimen; specifically, when the specimen is subjected to a pressure of 0.8 N... f When the coil is energized, the pressure on the sample drops to 0.3N. f The current is reduced during operation. This invention is equipped with a corresponding rectifier to convert alternating current (AC) into stable direct current (DC). This DC current generates a stable magnetic field through the coil, and the stiffness of the magnetorheological elastic body changes under the influence of the magnetic field. The magnitude of the magnetic induction generated by a single-turn circular coil at a point P in space is calculated using a formula, and the magnetic field strength can be adjusted by controlling the current.

[0053]

[0054] H P —The magnitude of the magnetic field generated at point P by a single-turn coil;

[0055] M—Divides the circumference of the coil into equal unit lengths;

[0056] I—Current in the coil;

[0057] R—coil radius;

[0058] The distance from the center of the circle to the projection point of point X—P onto the coil surface;

[0059] m — takes a value from 0 to M, and is the length of the m-th unit;

[0060] K—The radius of the circle is divided into K equal radial units;

[0061] k — takes a value from 0 to K-1, and is k times the radial unit length;

[0062] Q—Divide the distance from point P to the projection of point P onto the coil surface into Q equal parts;

[0063] q — takes a value from 0 to 2Q, and takes the qth equal division distance.

[0064] Working principle of this invention:

[0065] When the coil is not energized, the stiffness of the CFRP-magnetorheological elastomer sandwich column is approximately 0.5 times that of the specimen. Test data obtained from the compression device with the coil de-energized are more accurate before the specimen reaches its peak load-bearing capacity, i.e., during the rising phase of the stress-strain curve. Just before reaching the peak load-bearing capacity, the coil is energized, and the stiffness of the CFRP-magnetorheological elastomer sandwich column increases to approximately 1.5 times that of the specimen. Based on existing material properties, when the CFRP-magnetorheological elastomer sandwich column is subjected to a magnetic induction intensity of 2T, its stiffness can... To meet the stiffness requirements of the invention, during the descent phase of the curve, after the specimen fails, the load-bearing capacity decreases, but the hydraulic cylinder pressure does not decrease rapidly. The CFRP-magnetorheological elastomer sandwich column has high stiffness, and the reduced load-bearing capacity of the specimen is borne by the CFRP-magnetorheological elastomer sandwich column. As the hydraulic cylinder continues to pressurize, the strain of the specimen and the CFRP-magnetorheological elastomer sandwich column increases. However, the stress-strain ratio of the specimen is in the descent phase, meaning the pressure borne by the specimen is still decreasing. Therefore, the stress-strain ratio of the CFRP-magnetorheological elastomer sandwich column increases. In the later stage of the descent curve, adjusting the coil current reduces the stiffness of the magnetorheological elastomer, thus reducing the difficulty of pressurizing the compression testing device and increasing the strain rate. The coil current and stress-strain curves controlling the magnetic field around the magnetorheological elastomer in this invention are shown below. Figure 4 As shown.

[0066] The pressure relationship of this invention is as follows:

[0067] F = F N +F a +F C

[0068] F—Total pressure of the hydraulic cylinder;

[0069] F N —The pressure exerted on the experimental specimen;

[0070] F a —The pressure that magnetorheological elastic bodies can withstand;

[0071] F C —The pressure that the CFRP core can withstand.

[0072] Figure 5 This is a graph showing the relationship between the pressure exerted on the experimental specimen of this invention and the total pressure of the hydraulic cylinder and the axial displacement.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the ideas of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A brittle material compression test device assisted by CFRP-magnetorheological elastomer loading, characterized in that, The load frame comprises a lower crossbeam, a pressing plate, an upper crossbeam, an upper stand and a lower stand; the lower crossbeam is provided with two lower stands, the upper stand is arranged on the lower stand, and the top end of the upper stand is supported and fixed on the bottom surface of the upper crossbeam; the diameter of the upper stand is smaller than that of the lower stand, the pressing plate is provided with two through holes, the two upper stands pass through the corresponding through holes, and the bottom surface of the pressing plate is supported on the top end of the lower stand and can move up and down along the upper stand; the bottom surface of the upper crossbeam and the top surface of the lower crossbeam are both provided with gaskets, the sample top is installed with a load sensor, and then the whole is installed between the two gaskets; the bottom surface of the upper crossbeam is provided with two cylindrical gaskets, and the supporting mechanism is arranged between the pressing plate and the cylindrical gaskets; the pressure mechanism is arranged on the lower crossbeam, and the pressure mechanism realizes the application of axial pressure on the sample through the transmission of the pressing plate; The load frame, support mechanism, pressure mechanism and data acquisition and processing mechanism; the load frame is divided into upper and lower two layers, the upper layer is used for placing the sample, the lower layer is installed with the pressure mechanism, the pressure mechanism applies axial pressure to the sample from the lower direction; the data acquisition and processing mechanism includes: load sensor, displacement sensor and controller, the load sensor is installed on the top of the sample to measure the axial pressure applied by the pressure mechanism, the displacement sensor is arranged on the side of the sample to measure the strain of the sample, and the controller draws the stress-strain curve according to the axial pressure and the strain; the device is provided with two support mechanisms, the support mechanisms are arranged on the upper layer of the load frame and symmetrically arranged on the two sides of the sample, the support mechanism includes CFRP column core, magnetorheological elastomer, coil and lead cylinder, the magnetorheological elastomer is wrapped outside the CFRP column core, the coil is wound outside the magnetorheological elastomer, the lead cylinder is arranged between the adjacent two layers of coils, the controller controls the power-on or power-off of the coil, and then the rigidity of the CFRP-magnetorheological elastomer sandwich column is adjusted by controlling the magnetic field strength, and the rigidity control is based on the change of the bearing pressure of the sample, that is, when the pressure borne by the sample is 0.8N f , the coil is powered on, and when the pressure borne by the sample decreases to 0.3N f , the current is reduced. The supporting mechanism is a cylindrical structure, the outer diameter of the magneto-rheological elastomer is smaller than the inner diameter of the innermost coil and has a space of 0.5 cm, so as to accommodate the transverse expansion caused by the vertical compression of the magneto-rheological elastomer, and the outermost coil is wrapped with a beryllium bronze alloy shell to reduce the diffusion of the magnetic field; The diameter of the cylindrical gasket is greater than the outer diameter of the magneto-rheological elastomer and smaller than the inner diameter of the innermost coil, and the central axis of the cylindrical gasket is on the same straight line as the central axis of the magneto-rheological elastomer; before the axial pressure is applied, the cylindrical gasket is in contact with the magneto-rheological elastomer, and in the process of compressing the test piece, the cylindrical gasket can be inserted into the innermost coil to compress the sandwich column composed of CFRP and the magneto-rheological elastomer; The pressure mechanism is a hydraulic cylinder, and the oil inlet and oil outlet of the hydraulic cylinder are controlled by the controller; The preparation process of the magneto-rheological elastomer comprises the following steps: putting a rubber matrix, magnetic particles and all filling materials into a rubber mixing machine, mechanically uniformly stirring, then placing in a high-temperature vacuum barrel to remove bubbles, and then injecting into an aluminum mold; pouring vulcanizing agent and vulcanizing accelerator into the mold, vulcanizing at high temperature, and preparing anisotropic cylindrical magneto-rheological elastomer by applying a magnetic field during vulcanization. The upper cross beam, the pressing plate, the lower cross beam, the upper stand column, the lower stand column, the cylindrical cushion block and the gasket are made of non-magnetic stainless steel, the magnetic permeability of which is 1.001-1.01 H / m, the Young's modulus is 200 GPa, and the density is 7.7 g / cm 3 ; The CFRP column core is a high-performance composite material which is glued by carbon fiber as reinforcement and resin as matrix through pultrusion, winding and molding processes; the carbon fiber is prepared by high-temperature carbonization and graphitization of organic fiber, and has a density of 1.8 g / cm 3 The microcrystalline graphite material has a carbon content of more than 90%.

2. The CFRP-magnetorheological elastomer assisted loading brittle material compression test device of claim 1, wherein, The method comprises the following steps:

3. A method for compression test of brittle material assisted by CFRP-magnetorheological elastomer, characterized in that, (1) preparing a plurality of rock samples with the same size and composition; installing the sample, the load sensor and the displacement sensor, connecting the oil pump of the hydraulic cylinder and each sensor to the controller; (3) reinserting a new test piece for pressing, and in the early stage of the stress-strain curve rising, the coil is not powered on, the stiffness of the magneto-rheological elastomer is low, and the elasticity is strong; (2) Start pressurization without energizing the coil until the specimen fails, and record the peak pressure N f to the controller; (5) when the test piece reaches the ultimate bearing capacity, the bearing capacity begins to decrease, and due to the supporting effect of the sandwich column, the pressure borne by the sample decreases, preventing the phenomenon of test machine rebound, and in this process, the hydraulic cylinder is always pressurized by oil; (4) When the specimen pressure reaches 0.8N f When the specimen pressure reaches 0.8N, the controller controls the power supply to the coil to generate a magnetic field with a magnetic induction intensity of 2T, the stiffness of the magneto-rheological elastomer increases, and the stiffness of the CFRP-magneto-rheological elastomer sandwich column increases. (7) the controller calculates and processes the data collected by each sensor, finally obtains a complete stress-strain curve, and displays the curve on the display screen. (6) The late stage of the descending section of the stress-strain curve, the bearing capacity of the specimen is not much reduced, when the bearing capacity of the specimen is reduced to 0.3N f When the bearing capacity of the specimen is reduced to 0.3N, the size of the adjusting current is adjusted, the magnetic induction intensity of the magnetic field is controlled in 0.8T-1.2T, the stiffness of the magneto-rheological elastomer is reduced, and the strain rate is improved. ​

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