Apparatus and method for measuring the shear flexoelectric coefficient of non-newtonian fluid dielectrics

Abstract

The application discloses an experimental device and method for measuring a shear flexoelectric coefficient of a non-Newtonian fluid dielectric, which comprises a ladder-shaped container made of an insulator material, a cylindrical rotor located at a central axis in the container, a torque motor connected with the cylindrical rotor, metal electrodes fixed on inner surfaces of the upper and lower parts of the container, a charge amplifier connected with the electrodes, and a signal processing module connected with the charge amplifier; the torque motor is used to rotate the cylindrical rotor to generate a gradient velocity and a strain on the non-Newtonian fluid in the container; the non-Newtonian fluid dielectric generates a shear strain gradient in the axial and radial directions to produce a flexoelectric effect polarization; the polarization charges on the electrodes are sent to the charge amplifier through the electrodes and are converted into voltage signals to be transmitted into the signal processing module to obtain the number of charges; and then, the shear flexoelectric coefficient of the non-Newtonian fluid dielectric can be obtained by combining with the structural parameters of the container.

Description

Technical Field

[0001] This invention relates to the field of electromechanical coupling technology in materials science, specifically to an experimental apparatus and loading method for measuring the shear flexural conductivity of a non-Newtonian fluid dielectric. Background Technology

[0002] Flexural electricity refers to the phenomenon of material deformation caused by strain gradient polarization or electric field gradient. As a mechanoelectric coupling property widely present in all dielectric materials, flexural electricity is considered a promising alternative to piezoelectricity and has already been studied and applied in solid dielectric materials and liquid crystal materials. While the flexural electricity effect in non-Newtonian fluid dielectric materials may have significant implications for research in bioelectronics, programmed droplets, energy harvesting, and ion electronic devices, it remains largely unexplored due to a lack of theoretical and experimental methods. Summary of the Invention

[0003] To fill the gaps in related theoretical and application fields, the present invention aims to provide an experimental apparatus and loading method for measuring the shear flexural conductivity of non-Newtonian fluid dielectrics. The apparatus is designed to generate a shear strain gradient in a non-Newtonian fluid, thereby producing a flexural effect in the non-Newtonian fluid dielectric and calculating the shear flexural conductivity of the non-Newtonian fluid dielectric.

[0004] To achieve the above objectives, the present invention adopts the following technical solution.

[0005] An experimental apparatus for measuring the shear flexural conductivity of a non-Newtonian fluid dielectric includes a trapezoidal container 1 made of an insulating material, a cylindrical rotor 2 located on the central axis inside the trapezoidal container 1, a torque motor 3 connected to the upper end of the cylindrical rotor, a first electrode 4-1 fixed to the inner surface of the upper part of the trapezoidal container 1, a second electrode 4-2 fixed to the inner surface of the lower part of the trapezoidal container 1, a charge amplifier 5 connected to the first electrode 4-1 and the second electrode 4-2, and a signal processing module 6 connected to the output of the charge amplifier 5. The torque motor 3 applies torque to the non-Newtonian fluid inside the trapezoidal container 1 through the cylindrical rotor 2. The non-Newtonian fluid dielectric generates shear strain gradients along the axial and radial directions, resulting in polarization. Polarization charges of opposite signs and equal magnitudes are induced on the first electrode 4-1 and the second electrode 4-2.

[0006] The trapezoidal container 1 and the cylindrical rotor 2 are made of high-impedance insulating materials to ensure that there is no direct charge transfer between the first electrode 4-1 and the second electrode 4-2.

[0007] The first electrode 4-1 and the second electrode 4-2 are made of highly conductive metal.

[0008] The measurement accuracy of the charge amplifier 5 is sufficient to meet the requirements for micro-charge measurement of non-Newtonian fluid dielectrics.

[0009] The experimental apparatus for measuring the shear flexural conductivity of a non-Newtonian fluid dielectric uses a torque motor 3 to apply torque to the non-Newtonian fluid inside a trapezoidal container 1 via a cylindrical rotor 2. The non-Newtonian fluid dielectric generates shear strain gradients along the axial and radial directions, resulting in polarization. Polarization charges of opposite signs and equal magnitudes are induced on the first electrode 4-1 and the second electrode 4-2. By combining the measured charge quantity with the structural parameters of the trapezoidal container, the flexural conductivity equation can be solved to obtain the shear flexural conductivity of the non-Newtonian fluid dielectric.

[0010] The method for solving the shear flexural conductivity of a non-Newtonian fluid dielectric is as follows:

[0011] The cylindrical rotor 2 induces a corresponding shear flow of non-Newtonian fluid during axial torsion. A cylindrical coordinate system is established with the center of the bottom of the trapezoidal container 1 as the origin. Where ρ is the radial coordinate. Let z be the circumferential coordinate and z be the axial coordinate; the shear stress of a non-Newtonian fluid is expressed as follows:

[0012]

[0013] Where τ is the shear stress, η is the viscosity of the non-Newtonian fluid, V is the flow field velocity, γ is the shear strain, and t is time; a cylindrical rotor 2 with radius R1 rotates in a cyclic sinusoidal manner at a rotation frequency f, then the above relationship (1) can be expressed as:

[0014]

[0015] Integrating over time t, we get:

[0016]

[0017] Where V0 is the surface velocity amplitude of the cylindrical rotor, and R2(z) is the radius R2 of the trapezoidal container relative to the coordinate z; to simplify the calculation, under the assumption of low rotational frequency and speed, the strain amplitude is used, then the shear strain gradient along the z direction is:

[0018]

[0019] The average strain gradient along the z-direction is generalized as follows:

[0020]

[0021] Where h is the axial distance between the first and second electrodes, both of which are immersed in the fluid; then the shear strain at z = 0 and z = h is:

[0022]

[0023] Among them, R 2max and R 2min Let R2 be the maximum and minimum values ​​of the radius R2 of the trapezoidal container, respectively.

[0024] V0=ω0R1=2πfθ0R1 (7)

[0025] Where ω0 and θ0 are the maximum angular velocity and average rotational angle amplitude, respectively; considering that the electrode areas are not the same, the average area A is used. av :

[0026]

[0027] Among them, A h A0 and A0 are the cross-sectional areas of the trapezoidal formwork when z = h and z = 0, respectively; the flexural electrical effect of the material is expressed by the flexural electrical coefficient and the strain gradient as follows:

[0028]

[0029] Among them, P i μ eff γ and x represent the polarization degree, effective flexural coefficient, shear strain, and shear strain gradient direction, respectively; while the polarization degree is described as the ratio of charge to charge distribution area; combining equations (5) and (9), we obtain the formula for the shear flexural coefficient of a non-Newtonian fluid dielectric:

[0030]

[0031] Where Q0 is the measured charge;

[0032] By applying torque displacement to the cylindrical rotor 2, the polarization of the non-Newtonian fluid dielectric is obtained. The charge Q0 measured by the signal processing module 6 and the charge amplifier 5 is substituted into formula (10) to solve for the shear flexural coefficient of the non-Newtonian fluid dielectric.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1) This invention fills the gap in the field of measuring the shear-flexural conductivity coefficient of non-Newtonian fluid dielectrics.

[0035] 2) This invention uses a simple experimental measurement device, which has lower processing requirements and less experimental difficulty, and can realize real-time measurement of the shear flexural electrical effect of different types of non-Newtonian fluid dielectric materials.

[0036] In summary, the flexural conductivity of liquid materials obtained through the experimental apparatus and measurement method of this invention fills the gaps and deficiencies in the prior art. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the measurement system of the present invention. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] like Figure 1 As shown, an experimental apparatus for measuring the shear flexural conductivity of a non-Newtonian fluid dielectric includes a trapezoidal container 1 made of an insulating material, a cylindrical rotor 2 located on the central axis inside the trapezoidal container 1, a torque motor 3 connected to the upper end of the cylindrical rotor, a first electrode 4-1 fixed to the inner surface of the upper part of the trapezoidal container 1, a second electrode 4-2 fixed to the inner surface of the lower part of the trapezoidal container 1, a charge amplifier 5 connected to the first electrode 4-1 and the second electrode 4-2, and a signal processing module 6 connected to the output of the charge amplifier 5. The torque motor 3 applies torque to the non-Newtonian fluid inside the trapezoidal container 1 through the cylindrical rotor 2. The non-Newtonian fluid dielectric generates shear strain gradients along the axial and radial directions, resulting in polarization. Polarization charges of opposite signs and equal magnitudes are induced on the first electrode 4-1 and the second electrode 4-2. By combining the measured charge quantity with the structural parameters of the trapezoidal container, the shear flexural conductivity equation can be solved to obtain the shear flexural conductivity of the non-Newtonian fluid dielectric.

[0040] The method for solving the shear flexural conductivity of a non-Newtonian fluid dielectric is as follows:

[0041] The cylindrical rotor 2 induces a corresponding shear flow of non-Newtonian fluid during axial torsion. A cylindrical coordinate system is established with the center of the bottom of the trapezoidal container 1 as the origin. Where ρ is the radial coordinate. Let z be the circumferential coordinate and z be the axial coordinate; the shear stress of a non-Newtonian fluid is expressed as follows:

[0042]

[0043] Where τ is the shear stress, η is the viscosity of the non-Newtonian fluid, V is the flow field velocity, γ is the shear strain, and t is time; a cylindrical rotor 2 with radius R1 rotates in a cyclic sinusoidal manner at a rotation frequency f, then the above relationship (1) can be expressed as:

[0044]

[0045] Integrating over time t, we get:

[0046]

[0047] Where V0 is the surface velocity amplitude of the cylindrical rotor, and R2(z) is the radius R2 of the trapezoidal container relative to the coordinate z; to simplify the calculation, under the assumption of low rotational frequency and speed, the strain amplitude is used, then the shear strain gradient along the z direction is:

[0048]

[0049] The average strain gradient along the z-direction is generalized as follows:

[0050]

[0051] Where h is the axial distance between the first and second electrodes, both of which are immersed in the fluid; then the shear strain at z = 0 and z = h is:

[0052]

[0053] Among them, R 2max and R 2min Let R2 be the maximum and minimum values ​​of the radius R2 of the trapezoidal container, respectively.

[0054] V0=ω0R1=2πfθ0R1 (7)

[0055] Where ω0 and θ0 are the maximum angular velocity and average rotational angle amplitude, respectively; considering that the electrode areas are not the same, the average area A is used. av :

[0056]

[0057] Among them, A h A0 and A0 are the cross-sectional areas of the trapezoidal formwork when z = h and z = 0, respectively; the flexural electrical effect of the material is expressed by the flexural electrical coefficient and the strain gradient as follows:

[0058]

[0059] Among them, P i μ eff γ and x represent the polarization degree, effective flexural coefficient, shear strain, and shear strain gradient direction, respectively; while the polarization degree is described as the ratio of charge to charge distribution area; combining equations (5) and (9), we obtain the formula for the shear flexural coefficient of a non-Newtonian fluid dielectric:

[0060]

[0061] Where Q0 is the measured charge;

[0062] By applying torque displacement to the cylindrical rotor 2, the polarization of the non-Newtonian fluid dielectric is obtained. The charge Q0 measured by the signal processing module 6 and the charge amplifier 5 is substituted into formula (10) to solve for the shear flexural coefficient of the non-Newtonian fluid dielectric.

[0063] In a preferred embodiment of the present invention, the trapezoidal container 1 and the cylindrical rotor 2 are made of high-impedance insulating materials to ensure that there is no direct charge transfer between the first electrode 4-1 and the second electrode 4-2.

[0064] In a preferred embodiment of the present invention, the first electrode 4-1 and the second electrode 4-2 are made of a highly conductive metal with a surface oxide dielectric having a limited and uniform thickness and stable chemical properties. This prevents the system from generating the expected external electrical signal through a chemical reaction, while also providing good conductivity for a small order of magnitude of charge information, thereby enabling accurate measurement.

[0065] As a preferred embodiment of the present invention, the measurement accuracy of the charge amplifier 5 is sufficient to meet the micro-charge measurement requirements of non-Newtonian fluid dielectrics.

Claims

1. A measurement method for an experimental apparatus for measuring the shear flexural conductivity of a non-Newtonian fluid dielectric, the experimental apparatus comprising a trapezoidal container (1) made of an insulating material, a cylindrical rotor (2) located on the central axis inside the trapezoidal container (1), a torque motor (3) connected to the upper end of the cylindrical rotor, a first electrode (4-1) fixed on the inner surface of the upper trapezoidal container (1), a second electrode (4-2) fixed on the inner surface of the lower trapezoidal container (1), a charge amplifier (5) connected to the first electrode (4-1) and the second electrode (4-2), and a signal processing module (6) connected to the output terminal of the charge amplifier (5); the torque motor (3) applies torque to the non-Newtonian fluid inside the trapezoidal container (1) through the cylindrical rotor (2), and the non-Newtonian fluid dielectric generates shear strain gradients along the axial and radial directions to generate polarization, inducing polarization charges of opposite signs and equal magnitude on the first electrode (4-1) and the second electrode (4-2); Its features are: The experimental setup uses a torque motor (3) to apply torque to the non-Newtonian fluid inside the trapezoidal container (1) via a cylindrical rotor (2). The non-Newtonian fluid dielectric generates shear strain gradients along the axial and radial directions, resulting in polarization. Polarization charges of opposite signs and equal magnitude are induced on the first electrode (4-1) and the second electrode (4-2). By combining the measured charge amount with the structural parameters of the trapezoidal container, the flexural effect equation can be solved to obtain the shear flexural coefficient of the non-Newtonian fluid dielectric. The method for solving the shear flexural conductivity of a non-Newtonian fluid dielectric is as follows: The cylindrical rotor (2) induces a corresponding shear flow of non-Newtonian fluid during axial torsion. A cylindrical coordinate system is established with the bottom center of the truncated trapezoidal container (1) as the origin. ,in, Radial coordinates, For circumferential coordinates, z For axial coordinates; the shear stress of a non-Newtonian fluid is expressed as: （1） in, For shear stress, For non-Newtonian fluid viscosity. For the flow field velocity, For shear strain, Time; radius is The cylindrical rotor (2) rotates in a sinusoidal pattern at a frequency of [missing information]. If a rotation is performed, the relationship in equation (1) above can be expressed as: （2） Regarding time Integral result: (3) in The surface velocity amplitude of the cylindrical rotor. The radius of the trapezoidal container Relative to coordinates The magnitude of the strain; to simplify the calculation, under the assumption of low rotational frequency and rotational speed, the strain amplitude is used, then along... The shear strain gradient in the direction is: (4) along The average strain gradient in the direction is generalized as follows: (5) in, It is the axial distance between the first and second electrodes, both of which are immersed in the fluid; then and The shear strain at that time is: (6) in, and The radii of the trapezoidal container are respectively The maximum and minimum values, and (7) in, and These represent the maximum angular velocity and the average angular amplitude of rotation, respectively; considering the different electrode areas, the average area is used. : (8) in, and They are and The cross-sectional area of ​​the time-staircase descriptor; the flexural electrical effect of the material is expressed by the flexural electrical coefficient and the strain gradient as follows: (9) in, , , and These represent the polarization degree, effective flexural coefficient, shear strain, and shear strain gradient direction, respectively; while the polarization degree is described as the ratio of charge to the area of ​​charge distribution; combining equations (5) and (9), we obtain the formula for the shear flexural coefficient of a non-Newtonian fluid dielectric: (10) in, It is the measured amount of charge; The polarization of the non-Newtonian fluid dielectric is obtained by applying torque displacement to the cylindrical rotor (2), and the charge quantity measured by the signal processing module (6) and the charge amplifier (5) is then used. Substituting into formula (10), the shear flexural coefficient of the non-Newtonian fluid dielectric can be solved.

2. The measurement method of the experimental apparatus for measuring the shear flexural conductivity of a non-Newtonian fluid dielectric according to claim 1, characterized in that: The trapezoidal container (1) and cylindrical rotor (2) are made of high-impedance insulating material to ensure that there is no direct charge transfer between the first electrode (4-1) and the second electrode (4-2).

3. The measurement method of the experimental apparatus for measuring the shear flexural conductivity of a non-Newtonian fluid dielectric according to claim 1, characterized in that: The first electrode (4-1) and the second electrode (4-2) are made of highly conductive metal.

4. The measurement method of the experimental apparatus for measuring the shear flexural coefficient of a non-Newtonian fluid dielectric according to claim 1, characterized in that: The measurement accuracy of the charge amplifier (5) can meet the requirements for micro-charge measurement of non-Newtonian fluid dielectrics.

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