Design method of magnetorheological elastomer film material

Abstract

The design method of the magneto-rheological elastomer film material comprises the following steps: A, manufacturing and microstructure characterization of the magneto-rheological elastomer film material: putting magnetic nanoparticles into a rubber solution according to a proper weight percentage to obtain a mixed solution, then spin-coating the mixed solution on a substrate to obtain a liquid film, and drying the liquid film to obtain the magneto-rheological elastomer film material; and finally, putting the liquid film into a constant-temperature box, heating and curing to obtain the magneto-rheological elastomer film material, and representing the microstructure of the magneto-rheological elastomer film material by using an optical microscope or a scanning electron microscope. B, mechanical behavior simulation of the magnetorheological elastomer film material: constructing a magnetorheological elastomer film representative volume element according to a film microstructure characterization result and appropriate magnetic particle shape idealization treatment, selecting magnetic performance and mechanical performance parameters of the rubber matrix and the magnetic particles based on a test result, selecting boundary conditions according to load conditions, and simulating the mechanical behavior of the magnetorheological elastomer film material; using a sequential method to decouple the field problem, and finally outputting a finite element analysis result. And designing the magnetorheological elastomer film material based on a film manufacturing method, a film microstructure characterization result and a finite element analysis result. According to the design method of the magneto-rheological elastomer film material, test and computer simulation technologies are combined, the effectiveness of the design method is improved, and the design cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of microscale magnetorheological elastomer material design technology, specifically relating to a design method for magnetorheological elastomer thin film materials. Background Technology

[0002] Magnetorheological elastomers (MEEs) are multifunctional smart materials whose mechanical properties can be modulated by applying a magnetic field, making them suitable for applications such as shock absorbers, sensors, and actuators. Currently, research and applications of MEEs remain active, but primarily focus on large-scale materials, with less attention paid to microscale materials. Literature studies indicate that microscale MEE materials show promising application prospects in small-sized magnetically controlled soft robots and microelectromechanical systems (MEMS).

[0003] Simulation helps engineers design the composition and microstructure of magnetorheological elastomers (MLEs), thereby designing material and device performance. Simulation-based design reduces the number of experiments and lowers design costs. The microstructure of a MLE (i.e., the distribution of magnetic particles in the matrix) significantly impacts its performance; therefore, constructing an appropriate microstructure geometric model is crucial for the validity of simulation results. There are generally three methods for simulating MLEs: the magnetized particle interaction model considers the influence of microstructure but does not require solving for the local magnetic field; this method is suitable for designing high-performance new materials, but its drawback is that it is not suitable for designing high-concentration materials; the continuous model utilizes finite element analysis, requiring the solution of local magnetic and force fields; this method allows for systematic study of the influence of microstructure and is suitable for design; and the phenomenological model is developed based on experimental data, treating the MLE as a homogeneous continuum and disregarding the effect of microstructure. This method can predict the mechanical behavior of real structures under complex loading conditions and is suitable for engineering applications, but not for the early design of MLE devices.

[0004] Compared to large-scale materials, simulation is particularly important for the design of microscale magnetorheological elastomers because testing the mechanical properties of microscale materials under magnetic fields is more difficult. Nanoindenters or micro-tensile analyzers are commonly used to test the mechanical properties of microscale materials, but applying a magnetic field can cause these instruments to malfunction. Therefore, magnetic shielding devices are required when testing the mechanical properties of microscale magnetorheological elastomers under magnetic fields. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of existing technologies, this invention provides a design method for magnetorheological elastomer thin film materials.

[0006] The technical solution of the present invention is as follows: A method for designing a magnetorheological elastomer thin film material includes the following steps: A: Fabrication and microstructure characterization of magnetorheological elastomer thin film materials: 1) When preparing a rubber solution, it is optional to add an organic solvent; 2) Add the magnetic nanoparticles to the rubber solution obtained in step 1) at an appropriate weight percentage, and then mix them thoroughly and uniformly by mechanical mixing and / or ultrasonic vibration to obtain a mixed solution; 3) Spin-coat the mixed solution obtained in step 2) onto the substrate to obtain a liquid film. The film thickness is controlled by setting an appropriate spin-coating speed and spin-coating time. 4) Place the liquid film obtained in step 3) into a constant temperature oven and heat it to solidify to obtain the magnetorheological elastomer film material. The heating temperature is 60-100℃. During the heating and solidification process, it is possible to choose whether to apply a magnetic field to the liquid film. 5) Characterize the microstructure of the magnetorheological elastomer thin film material obtained in step 4) using an optical microscope or a scanning electron microscope; B: Simulation of the mechanical behavior of magnetorheological elastomer thin film materials: The mechanical behavior of a magnetorheological elastomer film, representing a volume element, was simulated using multiphysics simulation software.

[0007] (1) Select a magnetorheological elastomer film of appropriate size to represent the volume element. Based on the above microstructure characterization results of the film, the density of the rubber matrix, the density and weight percentage of the magnetic nanoparticles, and the appropriate geometric idealization of the magnetic particles, construct a geometric model of the magnetorheological elastomer film to represent the volume element. (2) Based on the test results, select appropriate parameters for the magnetic properties and mechanical properties of the rubber matrix and magnetic particles; (3) Select boundary conditions based on load conditions; (4) Use the sequential method to solve the coupled field problem, which includes multiple finite element analyses, each of which corresponds to a different field. The coupling of the two fields is achieved by loading the result of one analysis onto another analysis. (5) Output the relevant finite element analysis results; (6) Based on the above thin film manufacturing method, thin film microstructure characterization results and above finite element analysis results, implement the design of magnetorheological elastomer thin film material.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: The magnetorheological elastomer thin film material design method provided by this invention combines experimental and computer simulation techniques, improving the effectiveness of the design method. Specifically, the mechanical properties of the designed thin film material closely approximate the actual mechanical properties of the manufactured thin film. Since some key technical aspects of this method (such as the construction of the representative volume element microstructure of the thin film) are based on experiments, it can be used to handle engineering applications involving real materials and structures. Furthermore, in characterizing the mechanical behavior of the thin film, this method uses computer simulation instead of experiments, which not only reduces design costs but also solves the technical problem of the difficulty in testing the mechanical properties of magnetorheological elastomer thin film materials under magnetic field conditions. Attached Figure Description

[0009] Figure 1 This is a technical roadmap for the design method of magnetorheological elastomer thin film materials of the present invention.

[0010] Figure 2 SEM image of the microstructure of PDMS-10wt% carbonyl ferrorheological elastomer film.

[0011] Figure 3 The volume element geometric model represents the PDMS-10wt% carbonyl ferrorheological elastomer film.

[0012] Figure 4 The equivalent stress distribution (unit: MPa) of the cross section on the thickness symmetry plane of a representative volume element of a PDMS-10wt% carbonyl ferrorheological elastomer film under a strain of 0.1 at B=400mT. The magnetic field direction is perpendicular.

[0013] Figure 5 A schematic diagram of a tensile specimen of a 190-micrometer-thick PDMS-10wt% carbonyl ferrorheological elastomer film.

[0014] Figure 6 for Figure 5 The tensile test results and simulation results of the specimens shown are presented. Detailed Implementation

[0015] The present invention will be described in detail below with reference to specific embodiments. Example

[0016] The design of PDMS-10wt% carbonyl ferrorheological elastomer thin film, using Figure 1 The technical approach shown includes the following steps: A: Fabrication and microstructure characterization of PDMS-10wt% carbonyl iron thin films: 1) Mix PDMS prepolymer and curing agent at a weight ratio of 10:1, and use a glass rod to stir and ultrasonically vibrate to make the two components evenly mixed and defoamed to obtain PDMS solution; 2) Add 50 nm carbonyl iron particles to the PDMS solution obtained in step 1) at a weight percentage of 10 wt%, and then mix the components evenly and remove bubbles by stirring with a glass rod and ultrasonic vibration to obtain a PDMS-carbonyl iron mixed solution. 3) The PDMS-carbonyl iron mixed solution obtained in step 2) was spin-coated onto a 4-inch silicon wafer to obtain a liquid film at a spin-coating speed of 1000 rpm; 4) The liquid film obtained in step 3) is placed in a constant temperature oven and heated to solidify, thus obtaining PDMS-10wt% carbonyl ferrorheological elastomer film material. The heating temperature is 60℃, and the film thickness is 190 micrometers. 5) The microstructure of the PDMS-10wt% carbonyl ferrorheological elastomer thin film material obtained in step 4) was characterized using scanning electron microscopy (SEM). The characterization results are as follows ( Figure 2 The data shows that 50-nanometer carbonyl iron particles aggregate into micron-sized agglomerates randomly distributed within the PDMS matrix; B: Simulation of tensile test of PDMS-10wt% carbonyl ferrorheological elastomer film under magnetic field: The tensile test of a representative volume element of a PDMS-10wt% carbonyl ferrorheological elastomer film was simulated using the multiphysics simulation software ANSYS.

[0017] (1) A PDMS-10wt% carbonyl ferrorheological elastomer film was selected as the representative volume element size (60×10×6 micrometers). Based on the PDMS matrix density (1.04 g / cm³), 3 The density of carbonyl iron nanoparticles (0.5 g / cm³) 3 The volume percentage of carbonyl iron particles was calculated using the weight percentage (10wt%) and the weight percentage (%). Figure 2 The carbonyl iron nanoparticle aggregates shown were shaped into spheres to obtain a representative volume element geometric model of the PDMS-10wt% carbonyl ferromagnetorheological elastomer film. Figure 3 The carbonyl iron spherical particles have a diameter of 1.6-3 micrometers. (2) Based on the experimental results, the saturation magnetization, relative permeability, and coercivity of the carbonyl iron particles were selected to be 3.94 × 10⁻⁶. 4 A / m, 20.14, 1.46×10 4 A / m, the relative permeability of PDMS is 1; PDMS is set as a linear elastic isotropic material with an elastic modulus of 1.8 MPa and a Poisson's ratio of 0.49. (3) An excitation current is applied to the electromagnetic coil to generate a uniform magnetic field of B=400 mT, which is applied to the above representative volume element. The direction of the magnetic field is parallel to the width direction. The magnetic field condition is solved in the Maxwell 3D module to obtain the electromagnetic force distribution inside the film under the action of the external magnetic field. The electromagnetic load is mapped to the statics module through field coupling technology, and axial displacement boundary conditions are applied to simulate the tensile test. (4) Output the average stress of the representative volume element and the equivalent stress distribution of the cross section located on the thickness symmetry plane. Figure 4 ); (5) The above-mentioned thin film manufacturing method, thin film microstructure characterization results and above-mentioned finite element analysis results provide basic data for the design of PDMS-carbonyl ferrorheological elastomer thin film materials.

[0018] Experimental verification A PDMS-10wt% carbonyl ferrorheological elastomer thin film with a thickness of 190 micrometers was prepared using the above method. Cut samples from the film as shown below... Figure 5 The tensile specimen shown was subjected to tensile tests using a micro tensile tester under conditions of no magnetic field and an applied magnetic field (B=400mT). The tensile strain ranged from 0 to 0.3. The magnetic field was generated between two parallel permanent magnets, and a magnetic shield was used to shield the magnetic field to prevent interference with the normal operation of the micro tensile tester. Figure 6 The results are as follows: Tensile test results were obtained. The above simulation method was used to simulate the tensile tests of PDMS-10wt% carbonyl ferrorheological elastomer films under no magnetic field and magnetic field (B=400mT) conditions. Figure 6 As shown, the simulation results and experimental results fit well, thus verifying the effectiveness of the magnetorheological elastomer thin film material design method of the present invention.

Claims

1. A method for designing a magnetorheological elastomer thin film material, characterized in that, Includes the following steps: A: Fabrication and microstructure characterization of magnetorheological elastomer thin film materials: 1) When preparing a rubber solution, it is optional to add an organic solvent; 2) Add the magnetic nanoparticles to the rubber solution obtained in step 1) at an appropriate weight percentage, and then mix them thoroughly and uniformly by mechanical mixing and / or ultrasonic vibration to obtain a mixed solution; 3) Spin-coat the mixed solution obtained in step 2) onto the substrate to obtain a liquid film. The film thickness is controlled by setting an appropriate spin-coating speed and spin-coating time. 4) Place the liquid film obtained in step 3) into a constant temperature oven and heat it to solidify to obtain the magnetorheological elastomer film material. The heating temperature is 60-100℃. During the heating and solidification process, it is possible to choose whether to apply a magnetic field to the liquid film. 5) Characterize the microstructure of the magnetorheological elastomer thin film material obtained in step 4) using an optical microscope or a scanning electron microscope; B: Simulation of the mechanical behavior of magnetorheological elastomer thin film materials: The mechanical behavior of the magnetorheological elastomer film, representing the volume element, was simulated using multiphysics simulation software. (1) Select a magnetorheological elastomer film of appropriate size to represent the volume element. Based on the above microstructure characterization results of the film, the density of the rubber matrix, the density and weight percentage of the magnetic nanoparticles, and the appropriate geometric idealization of the magnetic particles, construct a geometric model of the magnetorheological elastomer film to represent the volume element. (2) Based on the test results, select appropriate parameters for the magnetic properties and mechanical properties of the rubber matrix and magnetic particles; (3) Select boundary conditions based on load conditions; (4) Use the sequential method to solve the coupled field problem, which includes multiple finite element analyses, each of which corresponds to a different field. The coupling of the two fields is achieved by loading the result of one analysis onto another analysis. (5) Output the relevant finite element analysis results; (6) Based on the above thin film manufacturing method, thin film microstructure characterization results and above finite element analysis results, implement the design of magnetorheological elastomer thin film material.

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