Device and method for measuring elastic-plastic deformation of thin film porous medium material

Abstract

The application discloses a device and method for measuring the elastic-plastic deformation of a thin film porous medium material under the action of normal stress and shear stress. The device comprises a hydraulic oil cylinder, a displacement sensor, a pressure sensor, a thrust bearing, an upper pressing plate, a lower pressing plate, a tangential tension shaft, a crossbar and a pulley, a weight, a thin rope, a shallow circular groove and a fixed support. The hydraulic oil cylinder is arranged on the fixed support, a plunger of the hydraulic oil cylinder is provided with the pressure sensor, the lower part of the pressure sensor is connected with the upper pressing plate through the thrust bearing, two tangential tension shafts are arranged on the upper pressing plate, the tangential tension shafts are connected with the thin rope, the thin rope is connected with the weight through the pulley, the lower pressing plate is fixed at the lower part of the fixed support, the upper end of the lower pressing plate is provided with the shallow circular groove, the thin film porous medium is placed in the shallow circular groove, and the displacement sensor is arranged on one side of the lower pressing plate. The device can measure the elastic-plastic characteristics of the thin film porous medium material under the action of normal stress, shear stress and osmotic pressure, and reflect the anisotropy characteristics of the porous medium material.

Description

Technical Field

[0001] This invention relates to the field of porous media material research technology, specifically to a device and method for measuring the elastic-plastic deformation of thin-film porous media materials under normal stress and shear stress. Background Technology

[0002] Porous media are substances composed of a solid framework and numerous densely packed micropores separated by the framework. A key characteristic of porous media materials is their channel structure, which gives them unique mechanical, adsorption, permeation, and filtration properties. These unique properties make them suitable for a wide range of applications, such as fuel cell plates, ion permeation membranes, and high-precision filtration separation.

[0003] Current research on porous thin-film materials mostly focuses on positive pressure, yet these materials exhibit significant anisotropy. In practical engineering applications, porous materials are subjected to complex mechanical stresses, thermal stresses, and fluid pressures. Evaluating the elasto-plastic deformation of porous materials under complex stress conditions remains a challenging problem. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a device and method for measuring the elastoplastic deformation of thin-film porous media materials under normal stress and shear stress, which can measure the elastoplastic deformation of thin-film porous media materials under the action of normal stress, shear stress and liquid osmotic pressure.

[0005] The technical solution of the present invention is as follows: A device for measuring the elastic-plastic deformation of a thin-film porous medium material under normal stress and shear stress includes a hydraulic cylinder, a displacement sensor, a pressure sensor, a thrust bearing, an upper pressure plate, a lower pressure plate, a tangential tension shaft, a crossbar and pulley, a weight, a thin rope, a shallow circular groove, and a fixed bracket. The hydraulic cylinder is located on the upper part of the fixed bracket. A pressure sensor is installed on the plunger of the hydraulic cylinder. The pressure sensor is connected to the upper pressure plate via a thrust bearing. Two tangential tension shafts are symmetrically arranged on the upper pressure plate. A thin rope is connected to the tangential tension shaft. The thin rope is connected to the weight via a pulley. The lower pressure plate is fixed to the lower part of the fixed bracket. A shallow circular groove is provided at the upper end of the lower pressure plate. The thin-film porous medium is placed in the shallow circular groove. The shallow circular groove is located directly below the upper pressure plate. A displacement sensor is provided on one side of the lower pressure plate.

[0006] The fixed bracket includes an upper mounting plate, columns, and a lower mounting plate. The upper and lower mounting plates are arranged parallel to each other and connected by four columns. The columns are perpendicular to the upper and lower mounting plates. A hydraulic cylinder is fixed above the upper mounting plate, and the axis of the hydraulic cylinder is perpendicular to the upper mounting plate. A lower pressure plate is vertically fixed on the lower mounting plate and coaxial with the hydraulic cylinder. A pulley is set on a crossbar, and both ends of the crossbar are fixed to the columns.

[0007] A measurement method based on a device for measuring the elastic-plastic deformation of a thin-film porous medium under normal stress and shear stress includes the following steps: 1) Calculate the average normal stress σ of the thin-film porous medium; 2) Calculate the shear stress τ of the thin-film porous medium; 3) Calculate the strain e of the thin-film porous medium (14); 4) Calculate the supporting force F3 generated by the osmotic pressure p of the liquid in the thin-film porous medium (14) on the thin-film porous medium (14); 5) By changing the pressure of the hydraulic cylinder (1), the tension of the weight (9), and the osmotic pressure of the liquid in the shallow circular groove (15), the normal stress σ and tensile stress τ of the thin-film porous medium (14) are controlled to obtain the anisotropic elastic-plastic deformation characteristics of the thin-film porous medium (14).

[0008] The normal stress on the thin-film porous medium is obtained as follows: the pressure inside the hydraulic cylinder increases, the piston of the hydraulic cylinder moves downward, and pressure is generated between the upper and lower pressure plates. The pressure value F1 is measured by a pressure sensor, and the average normal stress σ is calculated based on the area of ​​the thin-film porous medium.

[0009]

[0010] In the formula: F1 is the pressure value measured by the pressure sensor; A is the area of ​​the thin-film porous medium.

[0011] The shear stress on the porous membrane medium is obtained as follows: a tangential tension shaft and a thin rope are installed on the upper pressure plate. The thin rope is connected to a weight via a pulley, generating a rotational torque M. A thrust bearing is installed on the top of the hydraulic cylinder plunger and does not bear the rotational torque. Therefore, the rotational torque M is equal to the frictional torque between the porous membrane medium and the upper pressure plate. The frictional torque generates a shear stress τ within the porous membrane medium. The shear stress τ is:

[0012]

[0013] In the formula: F2 is the pulling force generated by the weight; r is the lever arm length of the rotational torque; R is the radius of the thin film porous medium.

[0014] The strain of the thin-film porous medium is obtained by measuring the displacement Δx under normal stress σ and shear stress τ using a laser displacement sensor (2), and obtaining the strain e of the thin-film porous medium (14) based on the thickness of the thin-film porous medium (14):

[0015]

[0016] In the formula: Δx is the displacement under normal stress and shear stress; h is the thickness of the thin film porous medium.

[0017] The osmotic pressure of different liquids in the porous membrane medium is obtained by placing the porous membrane medium (14) in a shallow circular groove (15) and adding a liquid (such as water, glycerol, etc.). The osmotic pressure p of the liquid in the porous membrane medium (14) generates a supporting force F3 on the porous membrane medium (14), which increases the stiffness of the porous membrane medium (14). The supporting force F3 is:

[0018] F3=p·2πRh (Equation 4);

[0019] In the formula: p is the osmotic pressure of the liquid in the thin-film porous medium; R is the radius of the thin-film porous medium; h is the thickness of the thin-film porous medium.

[0020] By comparing the forces acting on the thin-film porous medium in different liquids, the osmotic pressure of the liquid in the thin-film porous medium can be obtained.

[0021] The present invention has the following beneficial effects:

[0022] 1. The measuring device designed in this invention can realize the measurement of elastic-plastic deformation of thin-film porous media under normal stress.

[0023] 2. The measuring device designed in this invention can apply torque to the surface of a thin-film porous medium to form shear stress, and measure the elastoplastic deformation of the thin-film porous medium material under the coupling action of normal stress and shear stress.

[0024] 3. The measuring device designed in this invention places the porous thin film medium in a liquid, subjecting the medium to osmotic pressure, and measures the elastic-plastic deformation of the porous thin film medium under the coupled action of normal stress, shear stress and osmotic pressure.

[0025] 4. This invention solves the problem that existing experimental devices and methods cannot separately measure the elastoplastic deformation of thin-film porous media caused by normal stress, shear stress and osmotic pressure. It superimposes the three stresses (normal stress, shear stress and osmotic pressure) one by one, which more accurately reflects the anisotropic characteristics of thin-film porous media materials. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a device for measuring the elastic-plastic deformation of a thin-film porous medium material under normal stress and shear stress.

[0027] Figure 2 This is a schematic diagram of the upper pressure plate.

[0028] Figure 3 This is the intention of the lower pressure plate.

[0029] In the diagram: 1-Hydraulic cylinder, 2-Displacement sensor, 3-Pressure sensor, 4-Thrust bearing, 5-Upper pressure plate, 6-Lower pressure plate, 7-Tangential tension shaft, 8-Crossbar and pulley, 9-Weight, 10-Screw, 11-Upper mounting plate, 12-Lower mounting plate, 13-Column, 14-Thin porous medium, 15-Shallow circular groove. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] like Figure 1-3 As shown, a device for measuring the elastoplastic deformation of a thin-film porous medium material under normal stress and shear stress includes a hydraulic cylinder 1, a displacement sensor 2, a pressure sensor 3, a thrust bearing 4, an upper pressure plate 5, a lower pressure plate 6, a tangential tension shaft 7, a crossbar and pulley 8, a weight 9, a thin rope 10, a shallow circular groove 15, and a fixed bracket. The hydraulic cylinder 1 is located on the upper part of the fixed bracket. The pressure sensor 3 is installed on the plunger of the hydraulic cylinder 1. The pressure sensor 3 is connected to the upper pressure plate 5 below through the thrust bearing 4. Two tangential tension shafts 7 are symmetrically arranged on the upper pressure plate 5. The thin rope 10 is connected to the tangential tension shaft 7. The thin rope 10 is connected to the weight 9 through the pulley. The lower pressure plate 6 is fixed to the lower part of the fixed bracket. The upper end of the lower pressure plate 6 is provided with a shallow circular groove 15. The thin-film porous medium 14 is placed in the shallow circular groove 15. The shallow circular groove 15 is located directly below the upper pressure plate 5. The displacement sensor 2 is provided on one side of the lower pressure plate 6.

[0032] The fixed bracket includes an upper mounting plate 11, columns 13, and a lower mounting plate 12. The upper mounting plate 11 and the lower mounting plate 12 are arranged parallel to each other and connected by four columns 13. The columns 13 are perpendicular to the upper mounting plate 11 and the lower mounting plate 12. A hydraulic cylinder 1 is fixed above the upper mounting plate 11, and the axis of the hydraulic cylinder 1 is perpendicular to the upper mounting plate 11. A lower pressure plate 6 is vertically fixed on the lower mounting plate 12 and coaxial with the hydraulic cylinder 1. A displacement sensor 2 is installed on the lower mounting plate 12. A pulley is installed on a crossbar, and both ends of the crossbar are fixed to the columns 13.

[0033] Method for calculating the normal stress on a thin-film porous medium: When the pressure inside the hydraulic cylinder 1 increases, the plunger moves downward, and pressure is generated between the upper pressure plate 5 and the lower pressure plate 6. The pressure value F1 is measured by the pressure sensor 3, and the average normal stress σ is calculated based on the area of ​​the thin-film porous medium.

[0034]

[0035] In the formula: F1 is the pressure value measured by the pressure sensor; A is the area of ​​the thin-film porous medium.

[0036] The method for calculating the shear stress on the porous membrane medium is as follows: A tangential tension shaft 7 and a thin rope 10 are installed on the upper pressure plate 5. The thin rope is connected to a weight via a pulley, generating a rotational torque M. The piston of the hydraulic cylinder 1 is connected to a thrust bearing 4 and does not bear the rotational torque. Therefore, the rotational torque M is equal to the frictional torque between the porous membrane medium and the upper pressure plate 5. This frictional torque generates shear stress τ within the porous membrane medium.

[0037]

[0038] In the formula: F2 is the pulling force generated by the weight; r is the lever arm length of the rotational torque; R is the radius of the thin film porous medium.

[0039] Method for calculating the strain of thin-film porous media: A laser displacement sensor 2 is installed on the lower mounting plate 12. The laser displacement sensor 2 measures the displacement Δx of the upper pressure plate under the action of normal stress σ and shear stress τ. Then, based on the thickness of the thin-film porous media 14, the strain e of the thin-film porous media is obtained.

[0040]

[0041] In the formula: Δx is the displacement under normal stress and shear stress; h is the thickness of the thin film porous medium.

[0042] A method for measuring the osmotic pressure of different liquids in a porous membrane medium involves designing a shallow circular groove in the lower pressure plate. The porous membrane medium is placed inside the groove, and a liquid (such as water or glycerol) is added. The osmotic pressure p of the liquid in the porous membrane medium generates a supporting force F3 on the porous membrane medium, thereby increasing the stiffness of the porous membrane medium.

[0043] F3=p·2πRh (Equation 4);

[0044] In the formula: p is the osmotic pressure of the liquid in the thin-film porous medium; R is the radius of the thin-film porous medium; h is the thickness of the thin-film porous medium.

[0045] By comparing the forces exerted on existing thin-film porous media materials in different liquids, the osmotic pressure of the liquid in the thin-film porous media can be obtained.

[0046] By changing the hydraulic cylinder pressure, the weight tension, and the liquid osmotic pressure in the shallow circular groove, the normal stress σ and tensile stress τ on the thin-film porous medium can be controlled, and the anisotropic elastoplastic deformation characteristics of the thin-film porous medium can be obtained. The influence of liquid osmotic pressure on the elastoplastic deformation of the thin-film porous medium can be analyzed.

[0047] In summary, a device for measuring the elastoplastic deformation of porous thin-film media under normal stress and shear stress can not only test the elastoplastic deformation of porous thin-film media under normal stress, but also measure the elastoplastic properties of porous thin-film media under shear stress and osmotic pressure, reflecting the anisotropic characteristics of porous media materials, and solving the problem that existing test devices and methods cannot measure the anisotropic elastoplastic deformation of porous media materials.

Claims

1. A device for measuring the elastic-plastic deformation of a thin-film porous medium material under normal stress and shear stress, comprising a hydraulic cylinder (1), a displacement sensor (2), a pressure sensor (3), a thrust bearing (4), an upper pressure plate (5), a lower pressure plate (6), a tangential tension shaft (7), a crossbar and pulley (8), weights (9), a thin rope (10), a shallow circular groove (15), and a fixed bracket, characterized in that: The hydraulic cylinder (1) is set on the upper part of the fixed bracket. A pressure sensor (3) is installed on the plunger of the hydraulic cylinder (1). The pressure sensor (3) is connected to the upper pressure plate (5) through a thrust bearing (4). Two tangential tension shafts (7) are symmetrically arranged on the upper pressure plate (5). A thin rope (10) is connected to the tangential tension shaft (7). The thin rope (10) is connected to the weight (9) through a pulley. The lower pressure plate (6) is fixed on the lower part of the fixed bracket. A shallow circular groove (15) is provided at the upper end of the lower pressure plate (6). A thin film porous medium (14) is placed in the shallow circular groove (15). The shallow circular groove (15) is located directly below the upper pressure plate (5). A displacement sensor (2) is provided on one side of the lower pressure plate (6).

2. As described in claim 1, characterized in that: The fixed bracket includes an upper mounting plate (11), a column (13) and a lower mounting plate (12). The upper mounting plate (11) and the lower mounting plate (12) are arranged parallel to each other. The upper mounting plate (11) and the lower mounting plate (12) are connected by four columns (13). The columns (13) are perpendicular to the upper mounting plate (11) and the lower mounting plate (12). The hydraulic cylinder (1) is fixed above the upper mounting plate (11). The axis of the hydraulic cylinder (1) is perpendicular to the upper mounting plate (11). The lower pressure plate (6) is vertically fixed on the lower mounting plate (12) and is coaxial with the hydraulic cylinder (1).

3. As described in claim 1, characterized in that: The pulley is mounted on the crossbar, and both ends of the crossbar are fixed to the column (13).

4. A measurement method based on the elastoplastic deformation measuring device for thin-film porous media materials under normal stress and shear stress as described in claim 1, characterized in that: Specifically, the following steps are included: 1) Calculate the average normal stress σ on the porous membrane medium; 2) Calculate the shear stress τ on the porous membrane medium; 3) Calculate the strain e of the porous membrane medium (14); 4) Calculate the supporting force F3 generated by the osmotic pressure p of the liquid in the porous membrane medium (14) on the porous membrane medium (14); 5) By changing the pressure of the hydraulic cylinder (1), the tension of the weight (9) and the osmotic pressure of the liquid in the shallow circular groove (15), the normal stress σ and tensile stress τ on the porous membrane medium (14) are controlled, and the anisotropic elastic-plastic deformation characteristics of the porous membrane medium (14) are obtained.

5. The measurement method as described in claim 4, characterized in that: The normal stress on the thin-film porous medium is obtained as follows: when the pressure inside the hydraulic cylinder (1) increases, the plunger of the hydraulic cylinder (1) moves downward, and pressure is generated between the upper pressure plate (5) and the lower pressure plate (6). The pressure value F1 is measured by the pressure sensor (3), and the average normal stress σ is calculated based on the area of ​​the thin-film porous medium (14). In the formula: F1 is the pressure value measured by the pressure sensor; A is the area of ​​the thin-film porous medium.

6. The measurement method as described in claim 4, characterized in that: The shear stress on the thin-film porous medium is obtained by installing a tangential tension shaft (7) and a thin rope (10) on the upper pressure plate. The thin rope (10) is connected to a weight (9) via a pulley (8), generating a rotational torque M. The top of the piston of the hydraulic cylinder (1) is equipped with a thrust bearing (4), which does not bear the rotational torque. Therefore, the rotational torque M is equal to the frictional torque between the thin-film porous medium (14) and the upper pressure plate (5). The frictional torque forms a shear stress τ in the thin-film porous medium (14). The shear stress τ is: In the formula: F2 is the pulling force generated by the weight; r is the lever arm length of the rotational torque; R is the radius of the thin film porous medium.

7. The measurement method as described in claim 4, characterized in that: The strain of the thin-film porous medium is obtained by measuring the displacement Δx under normal stress σ and shear stress τ using a laser displacement sensor (2), and obtaining the strain e of the thin-film porous medium (14) based on the thickness of the thin-film porous medium (14): In the formula: Δx is the displacement under normal stress and shear stress; h is the thickness of the thin film porous medium.

8. The measurement method as described in claim 4, characterized in that: The osmotic pressure of different liquids in the thin-film porous medium is obtained in the following way: a thin-film porous medium (14) is placed in a shallow circular groove (15), and a liquid is added. The osmotic pressure p of the liquid in the thin-film porous medium (14) generates a supporting force F3 on the thin-film porous medium (14), which increases the stiffness of the thin-film porous medium (14). The supporting force F3 is: F3=p·2πRh (Equation 4); In the formula: p is the osmotic pressure of the liquid in the thin-film porous medium; R is the radius of the thin-film porous medium; h is the thickness of the thin-film porous medium. By comparing the forces acting on the thin-film porous medium in different liquids, the osmotic pressure of the liquid in the thin-film porous medium can be obtained.

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