A method for measuring normal force of magneto-rheological fluid in non-uniform magnetic field based on COMSOL simulation

Abstract

The application relates to a method for measuring the normal force of a magneto-rheological fluid in a non-uniform magnetic field based on COMSOL simulation, a rheometer model with the same size as the MCR-302 rotary rheometer is established in COMSOL according to the size and internal structure of the MCR-302 rotary rheometer; at the same time, different currents are input into the MCR-302 rotary rheometer, the magnetic induction intensity of the experimental platform is measured by using a teslameter, then the excitation coil current in the COMSOL simulation model is set to be the same size, so that the number of turns of the coil is adjusted; during the experiment, the magneto-rheological fluid to be measured is placed on the test platform of the MCR-302 rotary rheometer, and a rotor is used to seal the magneto-rheological fluid, so that the magneto-rheological fluid keeps a cylindrical shape on the test platform of the rheometer; according to the actual situation of the magneto-rheological fluid, the normal force of the magneto-rheological fluid in the non-uniform magnetic field can be quickly and accurately obtained in COMSOL, and the cost is greatly reduced and the efficiency is improved.

Description

Technical fields:

[0001] This invention belongs to the field of intelligent material related parameter testing technology, and in particular relates to a method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation. Background technology:

[0002] Magnetorheological fluids are novel smart materials that are sensitive to magnetic fields and have controllable properties. In their natural state, their flow characteristics are similar to those of ordinary Newtonian fluids. However, under magnetic field excitation, the magnetic particles in the magnetorheological fluid will connect to form chain-like structures, leading to significant changes in parameters such as shear yield strength and viscosity. Among the various performance analyses of magnetorheological fluids, the normal force is a crucial mechanical parameter.

[0003] At present, many scholars have studied the normal force of magnetorheological fluids in uniform magnetic fields, but research on the normal force of magnetorheological fluids in non-uniform magnetic fields is very limited. In research fields such as magnetorheological polishing and magnetorheological flexible fixtures, the normal force characteristics of magnetorheological fluids in non-uniform magnetic fields are the real focus that needs to be paid attention to.

[0004] In today's society, various types of robots are being researched, developed, and deployed in different industries. Robots are playing an increasingly significant role in fields such as manufacturing, medicine, services, military, and rescue. Among them, flexible robots are very suitable for solving some complex and sensitive problems. Due to their degrees of freedom and compliant structure, flexible robots can achieve functions that traditional rigid structure robots cannot. Even simple, low-cost flexible robots can have high flexibility and strong adaptability. As a result, researchers have applied magnetorheological fluids to the actuators of robots. Therefore, how to quickly and accurately obtain the normal force of magnetorheological fluids in non-uniform magnetic fields has become an engineering challenge that needs to be solved.

[0005] This invention is funded by the Quanzhou Municipal Science and Technology Program (2021C007R). Summary of the Invention:

[0006] In view of this, the purpose of the present invention is to provide a method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation. This method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation can quickly, efficiently and accurately obtain the normal force of magnetorheological fluid in a non-uniform magnetic field.

[0007] The present invention specifically adopts the following technical solution:

[0008] First, a model of the MCR-302 rotating rheometer with the same dimensions and internal structure was created in COMSOL. Simultaneously, different currents were applied to the MCR-302 rotating rheometer, and the magnetic flux density of the experimental platform was measured using a teslameter. Then, the excitation coil current in the COMSOL simulation model was set to the same value, thereby adjusting the number of coil turns. During the experiment, the magnetorheological fluid to be tested was placed on the test platform of the MCR-302 rotating rheometer, and a rotor was used to seal the magnetorheological fluid, maintaining its cylindrical shape on the test platform. In C... In OMSOL, based on the actual situation of the magnetorheological fluid, the volume fraction of the magnetorheological fluid, the particle size of the magnetic particles, the permeability, the density of the magnetic particles, the volume of the magnetorheological fluid, the formula for calculating the normal force, and the magnitude of the current flowing through the rheometer are set. In each simulation, different volume fractions are selected under the same current magnitude, or the current magnitude is changed under the same volume fraction of magnetorheological fluid. The above simulation process is repeated to obtain the normal force of the magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation. By comparing the magnitude of the normal force in the COMSOL simulation and the experiment, the magnitude of the normal force of the magnetorheological fluid in a non-uniform magnetic field can be determined.

[0009] Preferably, it includes the following steps:

[0010] Step S01: Measure the dimensions of the MCR-302 rotational rheometer;

[0011] Step S02: Place the magnetorheological fluid to be tested on the test platform of the rheometer;

[0012] Step S03: Current is passed into the rheometer to generate a magnetic field;

[0013] Step S04: Measure the normal force of the magnetorheological fluid in a non-uniform magnetic field, and conduct multiple sets of experiments;

[0014] Step S05: Create an identical model in COMSOL using the MCR-302 rotational rheometer described in Step S01;

[0015] Step S06: Define the material properties of the magnetorheological fluid in COMSOL. The key properties include the volume fraction of the magnetorheological fluid, magnetic permeability, formula for calculating normal force, and magnitude of current flowing into the rheometer.

[0016] Step S07: Select magnetorheological fluids with different volume fractions or change the current magnitude to conduct experimental simulations;

[0017] Step S08: Measure the magnitude of the normal force of the magnetorheological fluid in COMSOL;

[0018] Step S09: Analyze and compare the normal force obtained in step S08, and set up the next set of experimental simulations;

[0019] Step S10: Repeat steps S07-S09 to calculate the normal force of the magnetorheological fluid in a non-uniform magnetic field obtained from the COMSOL simulation.

[0020] Step S11: Compare the normal forces obtained in steps S04 and S08 under the same conditions to determine the magnitude of the normal force of the magnetorheological fluid in a non-uniform magnetic field.

[0021] Preferably, step S01 specifically includes: measuring the dimensions of the MCR-302 rotary rheometer, specifically measuring the three-dimensional drawing of the MCR-302 rotary rheometer, which includes the iron core, coil cover plate, copper coil, rotor and test platform.

[0022] Preferably, steps S02, S03, and S04 specifically include: placing the magnetorheological fluid to be tested on the test platform of the MCR-302 rotary rheometer, then passing an electric current through it to generate a non-uniform magnetic field in the rheometer, and the test platform keeping the magnetorheological fluid from flowing. A force sensor is installed on the rotor. When the magnetic field acts on the magnetorheological fluid, it generates an upward normal force, so that the sensor can collect and statistically analyze the generated normal force.

[0023] Preferably, steps S05 and S06 specifically include: First, selecting the two-dimensional axisymmetric module in the COMSOL simulation and establishing a model according to the external dimensions of the MCR-302 rotational rheometer; then selecting the materials for each component in the COMSOL simulation and defining the material properties; among which, the properties of the magnetorheological fluid need to be customized, and the basic properties include parameters such as vacuum permeability, permeability of non-magnetic continuous carrier, and average particle size of magnetic particles, while the variables include the volume fraction of the magnetorheological fluid, the permeability of magnetic particles, and the permeability of the magnetorheological fluid; then, selecting the coil module in the magnetic field module, measuring the magnetic induction line intensity using a Tesla meter on the test platform of the experimental prototype, and confirming by comparison that the number of coil turns in the COMSOL simulation is 450 turns, and that the magnitude of the current can be selected in the COMSOL simulation to change the current.

[0024] Preferably, step S07 specifically includes: using the controlled variable method, dividing the experiment into multiple groups for simulation; selecting the same volume fraction of magnetorheological fluid, changing the magnitude of the current to obtain the normal force generated; or using different volume fractions of magnetorheological fluid under the same current magnitude, observing the change in normal force, and finally performing the same steps in COMSOL simulation, using the normal force calculation formula to calculate the normal force.

[0025] Preferably, steps S08 and S09 specifically include: meshing the model in the COMSOL simulation, with the mesh setting of the magnetorheological fluid region being more refined, because it is necessary to calculate the normal force of the magnetorheological fluid on the contact surface of the cover plate, so that the mesh setting in its region is more refined; then, the magnetic induction intensity distribution in the model is obtained through steady-state calculation; in the results module, line integral is selected, the lower surface of the rotor is selected, and the normal stress formula is input; finally, the normal force of the magnetorheological fluid in the non-uniform magnetic field is calculated.

[0026] The formula for normal stress is:

[0027] s is the normal stress, m m For the permeability of a nonmagnetic continuous carrier, m p denoted as ρ, where f is the permeability of the magnetic particles, f is the volume fraction of the magnetorheological fluid, and H is the magnetic field strength.

[0028] Preferably, step S10 specifically includes: changing the current magnitude or changing the volume fraction of the magnetorheological fluid to repeat multiple sets of experiments to obtain its normal force, and collecting and organizing the data using an Excel spreadsheet.

[0029] Preferably, step S11 specifically includes: comparing the collected experimental data and simulation data to obtain the relationship between the normal force of the magnetorheological fluid and the current or magnetic induction intensity in a non-uniform magnetic field, which can more conveniently and directly obtain the desired normal force magnitude.

[0030] Advantages and effects of the present invention:

[0031] Compared with the prior art, the main advantages of the present invention and its preferred embodiment are: it can quickly and accurately obtain the normal force of magnetorheological fluid in a non-uniform magnetic field, and the normal force can be obtained by comparing COMSOL simulation and experiment at the same time. If the desired normal force is required, the current magnitude or volume fraction can be changed in the COMSOL simulation, which greatly reduces the cost and improves the efficiency. Attached Figure Description

[0032] To more clearly illustrate the technical solution of the present invention, the features and technical characteristics of the present invention will be more clearly described below in conjunction with the relevant accompanying drawings, wherein:

[0033] Figure 1 This is a three-dimensional structural diagram of the MCR-302 rotary rheometer, where 1—iron core, 2—coil cover plate, 4—cover plate, and 6—test platform;

[0034] Figure 2 This is a cross-sectional view of the MCR-302 rotational rheometer, where 3 is the copper coil and 5 is the magnetorheological fluid to be tested.

[0035] Figure 3 Mesh generation diagram of the experimental prototype in COMSOL simulation;

[0036] Figure 4 A two-dimensional plot of the calculations performed in a COMSOL simulation;

[0037] Figure 5 For 3D plotting of calculations in COMSOL simulation;

[0038] Figure 6 This is a schematic diagram of the overall testing process for the present invention. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0041] like Figure 6 As shown, the test steps of the method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation of the present invention are as follows:

[0042] First, a model of the MCR-302 rotational rheometer with the same dimensions and internal structure was created in COMSOL. Simultaneously, different currents were applied to the MCR-302 rotational rheometer, and the magnetic flux density of the experimental platform was measured using a teslameter. Then, the excitation coil current in the COMSOL simulation model was set to the same value, thereby adjusting the number of coil turns. During the experiment, the magnetorheological fluid to be tested was placed on the test platform of the MCR-302 rotational rheometer, and a rotor was used to seal the magnetorheological fluid, maintaining its cylindrical shape on the test platform. In CO... In MSOL, based on the actual situation of the magnetorheological fluid, the volume fraction of the magnetorheological fluid, the particle size of the magnetic particles, the permeability, the density of the magnetic particles, the volume of the magnetorheological fluid, the formula for calculating the normal force, and the magnitude of the current flowing into the rheometer are set. In each simulation, different volume fractions are selected under the same current magnitude, or the current magnitude is changed under the same volume fraction of magnetorheological fluid, and the above simulation process is repeated to obtain the normal force of the magnetorheological fluid in a non-uniform magnetic field based on the COMSOL simulation. By comparing the magnitude of the normal force in the COMSOL simulation and the experiment, the magnitude of the normal force of the magnetorheological fluid in a non-uniform magnetic field can be determined.

[0043] The detailed steps above are as follows:

[0044] Step S01: Specifically, this includes measuring the dimensions of the MCR-302 rotational rheometer, such as... Figure 1 , Figure 2 The image shown is a three-dimensional drawing of the MCR-302 rotary rheometer, which includes the core 1, coil cover 2, copper coil 3, rotor 4, and test platform 6.

[0045] Steps S02, S03, and S04 specifically include: placing the magnetorheological fluid to be tested on the test platform of the MCR-302 rotary rheometer, then passing an electric current through it to generate a non-uniform magnetic field in the rheometer, and keeping the magnetorheological fluid from flowing on the test platform. A force sensor is installed on the rotor. When the magnetic field acts on the magnetorheological fluid, it generates an upward normal force, which the sensor can collect and statistically analyze.

[0046] Steps S05 and S06 specifically include: First, in the COMSOL simulation, select the two-dimensional axisymmetric module and build a model according to the external dimensions of the MCR-302 rotational rheometer; then, select the materials for each component in the COMSOL simulation and define the material properties; the properties of the magnetorheological fluid need to be customized, and the basic properties include parameters such as vacuum permeability, permeability of non-magnetic continuous carrier, and average particle size of magnetic particles, while the variables include the volume fraction of the magnetorheological fluid, the permeability of the magnetic particles, and the permeability of the magnetorheological fluid; then, in the magnetic field module, select the coil module, and use a teslameter to measure the magnetic induction line intensity on the test platform of the experimental prototype. By comparison, it is confirmed that the number of coil turns in the COMSOL simulation is 450 turns, and the magnitude of the current can be selected in the COMSOL simulation to change the current.

[0047] Step S07: Specifically includes: using the controlled variable method, dividing the experiment into multiple groups for simulation; selecting the same volume fraction of magnetorheological fluid, changing the magnitude of the current to obtain the normal force generated; or using different volume fractions of magnetorheological fluid under the same current magnitude, observing the change of its normal force, and finally performing the same steps in COMSOL simulation, using the normal force calculation formula to calculate the normal force.

[0048] Steps S08 and S09 specifically include: meshing the model in the COMSOL simulation, such as... Figure 3 As shown, the mesh setting in the magnetorheological fluid region is relatively fine because it is necessary to calculate the normal force of the magnetorheological fluid on the contact surface of the cover plate. Therefore, the mesh setting in this region is more refined. Then, the magnetic induction intensity distribution in the model is obtained through steady-state calculation. In the results module, line integral is selected, the lower surface of rotor 4 is selected, and the normal stress formula is input. Finally, the normal force of the magnetorheological fluid in the non-uniform magnetic field is calculated.

[0049] The formula for normal stress is:

[0050] s is the normal stress, m m For the permeability of a nonmagnetic continuous carrier, m p denoted as ρ, where f is the permeability of the magnetic particles, f is the volume fraction of the magnetorheological fluid, and H is the magnetic field strength.

[0051] Step S10 specifically includes: changing the current magnitude or changing the volume fraction of the magnetorheological fluid, repeating multiple sets of experiments to obtain its normal force, and collecting and organizing the data using an Excel spreadsheet.

[0052] Step S11 specifically includes: comparing the collected experimental data and simulation data to obtain the relationship between the normal force of the magnetorheological fluid and the current or magnetic induction intensity in a non-uniform magnetic field, which can more conveniently and directly obtain the desired normal force magnitude.

[0053] The specific embodiments described above further illustrate the inventive purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, or improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring normal force of a magneto-rheological fluid in a non-uniform magnetic field based on COMSOL simulation, characterized in that, Specifically, the following steps are included: Step S01: Measure the dimensions of the MCR-302 rotational rheometer; Step S02: Place the magnetorheological fluid to be tested on the test platform of the rheometer; Step S03: Current is passed into the rheometer to generate a magnetic field; Step S04: Measure the normal force of the magnetorheological fluid in a non-uniform magnetic field, and conduct multiple sets of experiments; Step S05: Create an identical model in COMSOL using the MCR-302 rotational rheometer described in Step S01; Step S06: Define the material properties of the magnetorheological fluid in COMSOL. The key properties include the volume fraction of the magnetorheological fluid, magnetic permeability, formula for calculating normal force, and magnitude of current flowing into the rheometer. Step S07: Select magnetorheological fluids with different volume fractions or change the current magnitude to conduct experimental simulations; Step S08: Measure the magnitude of the normal force of the magnetorheological fluid in COMSOL; Step S09: Analyze and compare the normal force obtained in step S08, and set up the next set of experimental simulations; Step S10: Repeat steps S07-S09 to calculate the normal force of the magnetorheological fluid in a non-uniform magnetic field obtained from the COMSOL simulation. Step S11: Compare the normal forces obtained in steps S04 and S08 under the same conditions to determine the magnitude of the normal force of the magnetorheological fluid in a non-uniform magnetic field.

2. The method for measuring normal force of MRF in non-uniform magnetic field based on COMSOL simulation according to claim 1, characterized in that, Step S01 Measure the dimensions of the MCR-302 rotary rheometer. Specifically measure the three-dimensional drawing of the MCR-302 rotary rheometer, which includes the iron core (1), coil cover plate (2), copper coil (3), rotor (4) and test platform (6).

3. A method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation, as described in claim 1 or 2, characterized in that, Steps S02, S03, and S04 specifically include: placing the magnetorheological fluid to be tested on the test platform of the MCR-302 rotary rheometer, then passing an electric current through it to generate a non-uniform magnetic field in the rheometer, and keeping the magnetorheological fluid from flowing on the test platform. A force sensor is set on the rotor. When the magnetic field acts on the magnetorheological fluid, it generates an upward normal force, which the sensor can collect and statistically analyze.

4. The method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation according to claim 3, characterized in that, Steps S05 and S06 specifically include: First, in the COMSOL simulation, select the two-dimensional axisymmetric module and build a model according to the external dimensions of the MCR-302 rotational rheometer; then, select the materials for each component in the COMSOL simulation and define the material properties; the properties of the magnetorheological fluid need to be customized, and the basic properties include vacuum permeability, permeability of the non-magnetic continuous carrier, and average particle size parameter of the magnetic particles, while the variables include the volume fraction of the magnetorheological fluid, the permeability of the magnetic particles, and the permeability of the magnetorheological fluid; then, in the magnetic field module, select the coil module, and use a teslameter to measure the magnetic induction intensity on the test platform of the MCR-302 rotational rheometer. By comparison, confirm that the number of coil turns in the COMSOL simulation is 450 turns, and the magnitude of the current can be selected in the COMSOL simulation to change the current.

5. The method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation according to claim 4, characterized in that, Step S07 specifically includes: using the controlled variable method, dividing the experiment into multiple groups for simulation; selecting the same volume fraction of magnetorheological fluid, changing the magnitude of the current to obtain the generated normal force; or using different volume fractions of magnetorheological fluid under the same current magnitude, observing the change of its normal force, and finally performing the same steps in the COMSOL simulation, using the normal force calculation formula to calculate the normal force.

6. The method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation according to claim 5, characterized in that, Steps S08 and S09 specifically include: meshing the model in COMSOL simulation, with the mesh setting of the magnetorheological fluid region being more refined, because it is necessary to calculate the normal force of the magnetorheological fluid on the contact surface of the cover plate, so that the mesh setting in its region is more refined, and then the magnetic induction intensity distribution in the model is obtained through steady-state calculation. In the results module, line integral is selected, the lower surface of rotor (4) is selected, and the normal stress formula is input. Finally, the normal force of the magnetorheological fluid in the non-uniform magnetic field is calculated. The formula for normal stress is: For normal stress, μ m For the permeability of a nonmagnetic continuous carrier, μ p The magnetic permeability of the magnetic particles, denoted as the volume fraction of the magnetorheological fluid, and H as the magnetic field strength.

7. The method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation according to claim 5, characterized in that, Step S10 specifically includes: changing the current magnitude or changing the volume fraction of the magnetorheological fluid, repeating multiple sets of experiments to obtain its normal force, and collecting and organizing the data using an Excel spreadsheet.

8. A method for measuring the normal force of magnetorheological fluid in a non-uniform magnetic field based on COMSOL simulation, as described in claim 6 or 7, characterized in that, Step S11 specifically includes: comparing the collected experimental data and simulation data to obtain the relationship between the normal force of the magnetorheological fluid and the current or magnetic induction intensity in a non-uniform magnetic field, which can more conveniently and directly obtain the desired normal force magnitude.

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