Electromagnetic drive based flexible thin film elastic modulus measurement device and method

Abstract

This application relates to an electromagnetically driven device and method for measuring the elastic modulus of flexible thin films. The device includes an electromagnetic drive module, a composite beam sample module, a displacement measurement module, and an elastic modulus inversion module. The composite beam sample consists of a base beam, microchannels filled with conductive liquid metal, and a flexible thin film to be measured attached to its upper surface. During measurement, the composite beam is placed in a magnetic field and energized through the microchannels to generate distributed Lorentz forces that deform it. The deformation data is acquired through the displacement measurement module, and combined with the dimensionless scaling law relationship obtained through finite element calibration, the elastic modulus of the thin film is calculated by the inversion module. This invention achieves non-contact, uniform loading, improves measurement accuracy by utilizing multi-condition data inversion, and has universal applicability.

Description

Technical Field

[0001] This invention relates to the field of material mechanical property testing technology, specifically to a device and method for measuring the elastic modulus of flexible thin films based on electromagnetic drive. Background Technology

[0002] Flexible thin film materials are widely used in flexible electronic devices, wearable devices, and micro / nano structure systems due to their light weight, flexibility, and good mechanical adaptability. The elastic modulus, as an important parameter characterizing the mechanical properties of materials, is crucial for accurate measurement in materials design and engineering applications.

[0003] Existing methods for measuring the elastic modulus of flexible thin films mainly include nanoindentation, tensile testing, atomic force microscopy (AFM), and bulging methods. While these methods can measure the mechanical properties of thin films to some extent, they still have many limitations. For example, nanoindentation and AFM typically rely on high-precision instruments, have limited testing areas, and require high sample surface quality; tensile testing requires clamping and loading the film, which can easily introduce boundary effects and is not suitable for ultrathin or highly flexible materials; bulging methods require complex loading and sealing structures and have strict experimental conditions. Furthermore, most of these methods employ contact or localized loading methods, which can easily introduce localized stress concentrations or testing errors, making it difficult to achieve stable and uniform loading conditions.

[0004] Therefore, it is necessary to develop a method for measuring the elastic modulus of flexible films that is simple in structure, has controllable loading, and can achieve non-contact loading. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a flexible thin film elastic modulus measurement device and method based on electromagnetic drive. By energizing a microchannel and combining it with an external magnetic field to generate distributed electromagnetic force, non-contact and stable loading of a composite beam structure is achieved. Combined with multi-condition measurement, the elastic modulus of the thin film is inverted.

[0006] The technical solution of the present invention is as follows: An electromagnetically driven flexible thin film elastic modulus measuring device includes: An electromagnetic drive module is used to apply a controllable distributed electromagnetic load to the composite beam sample module. The composite beam sample module includes a base beam, microchannels disposed inside the base beam, conductive liquid metal filled in the microchannels, and a flexible thin film to be tested attached to the upper surface of the base beam. The displacement measurement module is used to measure the deformation displacement of the composite beam under electromagnetic load. A data acquisition and processing module, connected to the displacement measurement module, is used to acquire and process deformation displacement data; The elastic modulus inversion module is used to invert and calculate the elastic modulus of the flexible film based on the deformation displacement data and the pre-established scaling law relationship. The electromagnetic drive module includes a magnetic field generator for generating a magnetic field and a current controller electrically connected to the microchannel. The direction of the magnetic field, the direction of the current in the microchannel, and the direction of the generated electromagnetic force are perpendicular to each other.

[0007] Furthermore, the magnetic field generating device is a permanent magnet or electromagnet with two magnetic poles facing each other; the microchannel is arranged along the length of the base beam and has a rectangular cross-sectional shape.

[0008] Furthermore, the center of the cross-section of the microchannel coincides with the geometric center of the rectangular cross-section of the base beam, and the conductive liquid metal is a gallium-based alloy.

[0009] Furthermore, the displacement measurement module is an optical measurement system or a laser displacement sensor.

[0010] Furthermore, the elastic modulus inversion module includes: a model building unit, used to establish a theoretical prediction model of beam deformation based on electromagnetic driving conditions, structural geometric parameters and the scaling law relationship; and a parameter solving unit, used to compare the measured deformation displacement data with the theoretical prediction model, construct an error function, and solve the elastic modulus of the flexible film through an optimization algorithm.

[0011] The present invention also provides a method for measuring the elastic modulus of a flexible thin film based on electromagnetic drive, using the above-mentioned device, and including the following steps: S1: Prepare a composite beam sample, wherein the composite beam includes a base beam, a microchannel disposed therein, a conductive liquid metal filled in the microchannel, and a flexible thin film to be tested attached thereto. S2: Fix both ends of the composite beam and place it in a stable magnetic field generated by the electromagnetic drive module; S3: Apply current to the microchannel through the current controller to generate Lorentz force under the action of magnetic field, and apply distributed electromagnetic load to the composite beam; S4: Using the displacement measurement module, measure the deformation displacement of the composite beam sample under at least one current loading condition; S5: Based on the dimensionless scaling law of the associated electromagnetic load parameters, structural geometric parameters and deformation displacement, which were pre-calibrated by the finite element method, and the displacement data measured in S4, the elastic modulus of the flexible film is calculated by inversion.

[0012] Furthermore, in step S3, while keeping the magnetic field strength constant, multiple sets of electromagnetic loading with different intensities are achieved by changing the current magnitude, and multiple sets of displacement data are obtained accordingly in step S4; in step S5, the multiple sets of displacement data are used to jointly construct an error function for inversion calculation.

[0013] Furthermore, a parametric finite element model of the composite beam, including the base beam, microchannel, liquid metal, and flexible film, is established; a parameter space including current, magnetic field strength, geometric dimensions of each component, and material modulus is set, and a large number of numerical calculations are performed by changing the parameters to obtain the deflection at the measuring point position under different parameter combinations; the calculated data is processed to be dimensionless, and the dimensionless scaling law relationship is obtained by fitting.

[0014] Furthermore, the inversion calculation in step S5 specifically involves: constructing an error function between the theoretically predicted displacement and the experimentally measured displacement based on the scaling law, and using the gradient descent method or the least squares method optimization algorithm to solve for the elastic modulus of the flexible film that minimizes the error function.

[0015] The present invention also provides a composite beam structure for the above-mentioned apparatus and method, comprising: The base beam is made of polymer material and has clamping areas at both ends for fixing. Microchannels are embedded inside the base beam along its length, and the microchannels are filled with conductive liquid metal. A flexible film attached to the upper surface of the base beam; The microchannel is connected to an external current controller via a wire.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) By energizing the microchannel and combining it with an external magnetic field to generate distributed electromagnetic force, non-contact and uniform loading of the composite beam is achieved, avoiding the problem of local stress concentration caused by traditional indentation or clamping loading. (2) The inversion model is constructed by using multi-condition current loading, which reduces the impact of random errors on the results compared with the single-condition measurement method; (3) Based on the dimensionless scaling law of finite element calibration, a quantitative relationship between electromagnetic load and structural deformation is established, so that the measurement method has good scale adaptability and universality. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of a flexible thin film elastic modulus measuring device based on electromagnetic drive. Figure 2 This is a schematic diagram of the electromagnetic drive module structure; Figure 3a A schematic diagram of the overall structure of the composite beam and its fixed supports at both ends; Figure 3b This is a top view of the composite beam surface; Figure 3c This is a schematic diagram of a composite beam cross-section structure; Figure 4 A schematic diagram showing the arrangement of optical measuring points at the mid-span of the beam; Figure 5 This is a schematic diagram of the finite element model of the composite beam. Figure 6 This is a diagram showing the dimensionless scaling law relationship of the deformation of a composite beam under electromagnetic drive.

[0018] Among them, 1-composite beam; 2-power controller; 3-first clamping end; 4-second clamping end; 5-industrial camera; 6-light source; 7-base beam; 8-microchannel; 9-clamping area; 10-effective area; 11-flexible film to be tested; 12-base beam elastomer; 13-liquid metal; 14-measurement mark point. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] Example 1: An electromagnetically driven flexible thin film elastic modulus measurement device includes: an electromagnetic drive module for applying a controllable distributed electromagnetic load to a composite beam sample module; the composite beam sample module includes a base beam, a microchannel disposed inside the base beam, a conductive liquid metal filled in the microchannel, and a flexible thin film to be tested attached to the upper surface of the base beam; a displacement measurement module for measuring the deformation displacement of the composite beam under the electromagnetic load; a data acquisition and processing module connected to the displacement measurement module for acquiring and processing deformation displacement data; and an elastic modulus inversion module for inverting and calculating the elastic modulus of the flexible thin film based on the deformation displacement data and a pre-established scaling law relationship; wherein the electromagnetic drive module includes a magnetic field generator for generating a magnetic field and a current controller electrically connected to the microchannel, wherein the direction of the magnetic field, the direction of the current in the microchannel, and the direction of the generated electromagnetic force are perpendicular to each other.

[0021] Furthermore, the magnetic field generating device is a permanent magnet or electromagnet with two magnetic poles facing each other; the microchannel is arranged along the length of the base beam and has a rectangular cross-sectional shape.

[0022] Furthermore, the center of the cross-section of the microchannel coincides with the geometric center of the rectangular cross-section of the base beam, and the conductive liquid metal is a gallium-based alloy.

[0023] Furthermore, the displacement measurement module is an optical measurement system, including an industrial camera, an imaging lens, and a light source system.

[0024] Furthermore, the elastic modulus inversion module includes: a model building unit, used to establish a theoretical prediction model of beam deformation based on electromagnetic driving conditions, structural geometric parameters and the scaling law relationship; and a parameter solving unit, used to compare the measured deformation displacement data with the theoretical prediction model, construct an error function, and solve the elastic modulus of the flexible film through an optimization algorithm.

[0025] Example 2: This invention designs a flexible thin film elastic modulus measurement device based on electromagnetic drive. The overall device structure consists of an electromagnetic drive module, a composite beam sample module, a displacement measurement module, a data acquisition and processing module, and an elastic modulus inversion module.

[0026] 1. Electromagnetic drive module The electromagnetic drive module is used to apply controllable distributed loads to the composite beam and is the core drive unit for measurement. Its structural diagram is shown in the attached figure. Figure 2 As shown, the module includes a permanent magnet assembly and a current controller, as well as the arrangement of the permanent magnet assembly, the direction of the current, and the direction of the electromagnetic force.

[0027] (1) Permanent magnet assembly The permanent magnet assembly consists of two disk-shaped permanent magnets with their magnetic poles facing each other, forming a stable and approximately uniform magnetic field region in the area where the beam is located.

[0028] The magnetic field direction is preferably perpendicular to the length of the beam and orthogonal to the current direction in the microchannel to ensure that the electromagnetic force acts along the beam thickness. Magnetic field strength ( B The value can be selected according to the testing requirements, and is generally 0.2 T.

[0029] (2) Current controller A current controller is used to provide a stable and adjustable current input.

[0030] Current magnitude ( I It can be adjusted according to testing requirements to achieve electromagnetic loading of different intensities.

[0031] 2. Composite beam sample module As shown in Figure 3, the composite beam sample module structure includes a base beam, microchannels and liquid metal, flexible film and fixed support structure.

[0032] (1) Foundation beam The two ends of the base beam are fixed by clamping devices, forming a fixed support boundary condition. Fixed areas are set at both ends of the base beam, and the unfixed portion in the middle constitutes the effective deformation zone of the beam. The base beam is a rectangular cross-section beam structure, with a width denoted as [missing information]. w m The thickness is denoted as h m The main material of the base beam is a polymer elastic material such as PDMS.

[0033] The length of the effective deformation region is defined as L , which is the distance between the two fixed areas, is used to characterize the main area where the beam deforms under electromagnetic load.

[0034] Preferably, the length of the fixed region ( L clamp ) relative to the effective length ( L The size is relatively small, but the present invention does not strictly limit it, and its size can be adjusted according to the actual device structure.

[0035] (2) Microchannels and liquid metal Microchannels are arranged along the length of the base beam, and their cross-section is preferably rectangular (width...). w channel and height h channel The microchannel is filled with conductive liquid metal. The two ends of the microchannel are connected to a current control device via wires. When energized, a Lorentz force is generated under the influence of a magnetic field.

[0036] Preferably, the center of the cross-section of the microchannel coincides with the geometric center of the rectangular cross-section of the base beam, that is, it is located near the neutral layer of the beam.

[0037] It should be noted that the location of the microchannel is not limited to being located entirely in the neutral layer. Its relative position can be adjusted according to design requirements, but it is preferred to be located near the neutral layer.

[0038] (3) Flexible film The flexible film to be tested adheres to the upper surface of the substrate beam, forming a composite structure with the substrate beam.

[0039] Preferably, the flexible film covers the upper surface area of ​​the base beam in both the length and width directions, i.e., its length ( L film ) and width ( w film ) respectively correspond to the foundation beam ( L film = L , w film =w m ).

[0040] The flexible film can be fixed to the surface of the base beam by adhesive bonding, which includes, but is not limited to: attaching after applying adhesive, directly bonding after surface treatment, or other interface bonding methods.

[0041] Preferably, during the adhesion process, the film is kept in close contact with the substrate beam without any significant air gap, so as to avoid the influence of interface slippage on the measurement results.

[0042] It should be noted that the flexible film does not have separate boundary constraints. Its boundary conditions are determined by the fixed support structures at both ends of the base beam. The film participates in the deformation response of the overall structure through the adhesion between it and the base beam.

[0043] 3. Displacement Measurement Module This module is used to acquire spatial deformation information of the beam under electromagnetic loading. Optical measurement methods are preferred, including an industrial camera, imaging lens, and light source system.

[0044] like Figure 4 As shown, a measurement point is preferably set at half the span of the beam. Marking points are prepared on the side of the beam using a fine-tipped marker, and image data before and after loading is acquired using an image acquisition system. A feature point tracking method is used to process the acquired images and extract the displacement change of the measurement point in space, thereby obtaining the deflection information of the beam at the measurement point location.

[0045] 4. Data Acquisition and Processing Module This module is used to acquire, process, and transmit displacement data, and is electrically connected to the displacement measurement module. Specifically, it includes a data acquisition unit and a data processing unit, wherein: The data acquisition unit is used to receive image data or displacement signals from the optical measurement system; The data processing unit is used to process the collected data, including image preprocessing, feature extraction and displacement calculation, so as to obtain the displacement change of the measurement point before and after loading. The data processing unit can store, organize, and output displacement data from multiple loading conditions for subsequent elastic modulus inversion calculations.

[0046] 5. Elastic modulus inversion module This module is used to invert and calculate the elastic modulus of flexible films based on measured displacement data and pre-established scaling law relationships. Specifically, it includes a model building unit and a parameter solving unit, wherein: The model building unit is used to establish a theoretical prediction model for beam deformation based on electromagnetic driving conditions, structural geometric parameters, and scaling law relationships. The parameter solving unit is used to compare the measured displacement data of the measuring points with the theoretical model, construct an error function, and solve the elastic modulus of the flexible film through an optimization algorithm to minimize the error between the theoretical prediction result and the experimental measurement result.

[0047] Furthermore, the inversion calculation employs multiple sets of displacement data under different current conditions for joint inversion to improve the accuracy of the results.

[0048] The inversion module can output the elastic modulus of the flexible film and can be linked with the data acquisition and processing module to realize automatic data transmission and calculation.

[0049] Example 3: Unlike Example 1, the magnetic field generating device is an electromagnet.

[0050] Example 4: Unlike Example 1, the displacement measurement module is a laser displacement sensor.

[0051] Example 5: A method for measuring the elastic modulus of a flexible thin film based on electromagnetic drive includes the following steps: S1: Prepare a composite beam sample, wherein the composite beam includes a base beam, a microchannel disposed therein, a conductive liquid metal filled in the microchannel, and a flexible thin film to be tested attached thereto. S2: Fix both ends of the composite beam and place it in a stable magnetic field generated by the electromagnetic drive module; S3: Apply current to the microchannel through the current controller to generate Lorentz force under the action of magnetic field, and apply distributed electromagnetic load to the composite beam; S4: Using the displacement measurement module, measure the deformation displacement of the composite beam sample under at least one current loading condition; S5: Based on the dimensionless scaling law of the associated electromagnetic load parameters, structural geometric parameters and deformation displacement, which were pre-calibrated by the finite element method, and the displacement data measured in S4, the elastic modulus of the flexible film is calculated by inversion.

[0052] Furthermore, in step S3, while keeping the magnetic field strength constant, multiple sets of electromagnetic loading with different intensities are achieved by changing the current magnitude, and multiple sets of displacement data are obtained accordingly in step S4; in step S5, the multiple sets of displacement data are used to jointly construct an error function for inversion calculation.

[0053] Furthermore, a parametric finite element model of the composite beam, including the base beam, microchannel, liquid metal, and flexible film, is established; a parameter space including current, magnetic field strength, geometric dimensions of each component, and material modulus is set, and a large number of numerical calculations are performed by changing the parameters to obtain the deflection at the measuring point position under different parameter combinations; the calculated data is processed to be dimensionless, and the dimensionless scaling law relationship is obtained by fitting.

[0054] Furthermore, the inversion calculation in step S5 specifically involves: constructing an error function between the theoretically predicted displacement and the experimentally measured displacement based on the scaling law, and using the gradient descent method or the least squares method optimization algorithm to solve for the elastic modulus of the flexible film that minimizes the error function.

[0055] Example 6: A composite beam structure for use in the above-mentioned apparatus and method, comprising: The base beam is made of polymer material and has clamping areas at both ends for fixing. Microchannels are embedded inside the base beam along its length, and the microchannels are filled with conductive liquid metal. A flexible film attached to the upper surface of the base beam; The microchannel is connected to an external current controller via a wire.

[0056] The working principle of this invention is as follows: 1. Electromagnetic driving mechanism When an electric current is passed through the microchannel I Under an external magnetic field B Under the influence of the current, a Lorentz force is generated in the liquid metal. For a current uniformly distributed along the length of the beam, this body force can be equivalent to a distributed load per unit length: (1) 2. Scale law for the deformation of electromagnetically driven beams (1) Construction of dimensionless scaling law For a composite beam structure fixed at both ends, under the action of electromagnetic force, the beam mainly undergoes tensile deformation. The total electromagnetic force acting on the beam is: (2) This total force is the main external load that drives the deformation of the structure.

[0057] The deformation resistance of a structure is determined by its in-plane tensile stiffness, which is expressed as: (3) Dimensional analysis shows that the measuring point on the beam is located at... z Deflection in direction z With structural length The ratio should satisfy the following relationship: (4) Substituting equations (2) and (3), we obtain the following scaling law relationship: (5) Among them, G( ) is a dimensionless nonlinear function.

[0058] (2) Finite element calibration method Because this problem involves geometric nonlinearity, large deformation, and composite material coupling effects, the function G( This scaling law is difficult to obtain through analytical derivation. Therefore, this invention uses the finite element method for scaling law calibration. The specific steps are as follows: S1. Establish the parametric finite element model of the composite beam, as shown in the attached figure. Figure 5 As shown, a composite structural model is established, comprising a base beam, microchannels, liquid metal, and a flexible thin film. The total current is applied step-by-step in multiple loading steps, with each loading step corresponding to a current increment of less than 5% of the total current. Under given current and applied magnetic field conditions, the current distribution within the microchannels is calculated, and the electromagnetic force distribution is determined based on the Lorentz force relationship. This force is then applied as a body load to the structural mechanics model to solve for beam deformation and output the deflection at the measurement point.

[0059] S2. Setting parameter space: Current magnetic field strength Geometric dimensions ( , , , , , Microchannel elastomer modulus Film elastic modulus .

[0060] The baseline values ​​for each parameter are set as follows: I = 1.0 A、 B = 0.2 T、 L = 20 mm w m = 1 mm h m = 0.5mm, w channel =0.5 mm h channel = 0.25 mm h film = 10 μm E m = 1 MPa Efilm = 10 MPa.

[0061] S3. By changing the parameters and performing numerous numerical calculations, the deflection at the measuring point is obtained. .

[0062] S4. Perform dimensionless processing on the data and establish the scaling law relationship of equation (5).

[0063] The scaling law relationship obtained through the above steps is shown in the appendix. Figure 6 As shown. This scaling law relationship can be fitted to the following exponential relationship: (6) 3. Thin Film Elastic Modulus Inversion Method Based on the above electromagnetic drive and scaling law relationship, this invention realizes the inversion solution of the elastic modulus of flexible films through displacement measurement and multi-condition loading data.

[0064] (1) Obtaining deflection at measuring points Measurement points are arranged at the center of the composite beam surface. These measurement points can be marked by spraying speckle patterns. An optical measurement system (including a camera, imaging lens, and light source) is used to continuously collect data on the beam's deformation during loading.

[0065] By using image processing methods (feature point tracking methods), the spatial position changes of the measuring points before and after deformation are extracted, thereby obtaining the deflection data of each measuring point. , and (These are the initial position and the displacement position of the measuring point after loading, respectively).

[0066] (2) Obtain multi-condition loading data To improve the inversion accuracy, this invention conducts multiple sets of tests under different current conditions. Specifically, while maintaining the magnetic field strength... B Under constant conditions, apply multiple sets of different currents: I 1, I 2,..., I m Multiple sets of deflection data were obtained accordingly: , ..., .

[0067] (3) Construction of error function To achieve the inversion of the elastic modulus of the thin film, an error function based on multiple operating conditions is constructed: (7) m The number of current-loaded groups, To measure the deflection in the experiment, The theoretical prediction is based on the scaling law of equation (6).

[0068] (4) Modulus inversion solution method Minimize the error function using optimization algorithms such as gradient descent and least squares. Solve for the elastic modulus of the thin film. .

[0069] The composite beam structure and related functional units in the measuring device of the present invention can be prepared by the following method.

[0070] 1. Preparation of the base beam The base beam has a rectangular cross-section structure, and different materials and sizes can be selected according to testing requirements.

[0071] In the preferred embodiment: (i) Materials: Polymer materials (such as silicone rubber, polyurethane); (ii) Preparation methods include, but are not limited to: mold casting; additive manufacturing (3D printing).

[0072] Length of base beam ,width w With thickness It can be designed according to the target measurement range.

[0073] 2. Fabrication of microchannel structures A microchannel structure is formed along the length of the base beam, preferably with a rectangular cross-section. This can be achieved using the following methods: Method 1: Embedded molding. A removable core mold (such as a thin metal wire or polymer strip) is pre-embedded during the base beam molding process; the core mold is removed after molding to form a through-channel microchannel. Method 2: Layered bonding. Two separate substrate layers are prepared; a trench structure is fabricated on one of the layers (e.g., through etching or molding); the layers are then encapsulated using hot pressing or bonding to form closed microchannels. The dimensions of the microchannels can be designed according to requirements, and their width... w channel With height h channel Generally, it falls within the range of micrometers to millimeters.

[0074] 3. Liquid metal filling and electrode connection After the microchannels are formed, liquid metal is injected into the channels.

[0075] In a preferred embodiment: the liquid metal is a gallium-based alloy; it is filled using a syringe or a microfluidic pump; After filling: Set conductive electrodes at both ends of the microchannel; achieve electrical connection using conductive adhesive or mechanical crimping; seal the channel ports (e.g., using sealant) to prevent liquid metal leakage.

[0076] 4. Preparation and application of flexible films The flexible thin film to be tested can be obtained through the following methods: commercial thin film materials (such as polymer films); or custom films can be prepared by spin coating, casting, or other methods. The film is attached to the upper surface of the substrate beam to form a composite structure, specifically including: coating the substrate beam surface with a thin layer of adhesive; uniformly attaching the film and gently pressing to remove air bubbles; and curing the adhesive layer at room temperature or under heating conditions. Preferred guarantees: There are no obvious gaps between the film and the substrate; the interface is firmly bonded to avoid testing errors.

[0077] 5. Overall assembly of the device The prepared composite beam structure is installed in a fixed support device, so that its two ends form fixed support boundary conditions.

[0078] The device was then placed in a magnetic field region and connected to a current control device and a measurement system to complete the overall assembly.

[0079] The innovations of this invention are: (1) proposing an electromagnetic driving method based on the coupling effect of liquid metal microchannel energization and external magnetic field to achieve distributed, non-contact loading of composite beams. (2) constructing a dimensionless scaling law relationship between electromagnetic load and structural deformation to achieve quantitative correlation between structural deformation and system parameters. (3) establishing an inversion solution method for the elastic modulus of flexible films based on multi-condition displacement measurement data and scaling law model.

Claims

1. An electromagnetic drive based flexible thin film elastic modulus measurement device, characterized by, include: An electromagnetic drive module is used to apply a controllable distributed electromagnetic load to the composite beam sample module. The composite beam sample module includes a base beam, microchannels disposed inside the base beam, conductive liquid metal filled in the microchannels, and a flexible thin film to be tested attached to the upper surface of the base beam. The displacement measurement module is used to measure the deformation displacement of the composite beam under electromagnetic load. A data acquisition and processing module, connected to the displacement measurement module, is used to acquire and process deformation displacement data; The elastic modulus inversion module is used to invert and calculate the elastic modulus of the flexible film based on the deformation displacement data and the pre-established scaling law relationship. The electromagnetic drive module includes a magnetic field generator for generating a magnetic field and a current controller electrically connected to the microchannel. The direction of the magnetic field, the direction of the current in the microchannel, and the direction of the generated electromagnetic force are perpendicular to each other.

2. The flexible thin film elastic modulus measuring device based on electromagnetic drive according to claim 1, characterized in that, The magnetic field generating device is a permanent magnet or electromagnet with two magnetic poles facing each other; the microchannel is arranged along the length of the base beam and has a rectangular cross-sectional shape.

3. The flexible thin film elastic modulus measuring device based on electromagnetic drive according to claim 1 or 2, characterized in that, The center of the cross-section of the microchannel coincides with the geometric center of the rectangular cross-section of the base beam, and the conductive liquid metal is a gallium-based alloy.

4. The flexible thin film elastic modulus measuring device based on electromagnetic drive according to claim 1, characterized in that, The displacement measurement module is an optical measurement system or a laser displacement sensor.

5. The flexible thin film elastic modulus measuring device based on electromagnetic drive according to claim 1, characterized in that, The elastic modulus inversion module includes: a model building unit, used to establish a theoretical prediction model of beam deformation based on electromagnetic driving conditions, structural geometric parameters and the scaling law relationship; and a parameter solving unit, used to compare the measured deformation displacement data with the theoretical prediction model, construct an error function, and solve the elastic modulus of the flexible film through an optimization algorithm.

6. A method for measuring the elastic modulus of a flexible thin film based on electromagnetic drive, characterized in that, The apparatus according to any one of claims 1 to 5 comprises the following steps: S1: Prepare a composite beam sample, wherein the composite beam includes a base beam, a microchannel disposed therein, a conductive liquid metal filled in the microchannel, and a flexible thin film to be tested attached thereto. S2: Fix both ends of the composite beam and place it in a stable magnetic field generated by the electromagnetic drive module; S3: Apply current to the microchannel through the current controller to generate Lorentz force under the action of magnetic field, and apply distributed electromagnetic load to the composite beam; S4: Using the displacement measurement module, measure the deformation displacement of the composite beam sample under at least one current loading condition; S5: Based on the dimensionless scaling law of the associated electromagnetic load parameters, structural geometric parameters and deformation displacement, which were pre-calibrated by the finite element method, and the displacement data measured in S4, the elastic modulus of the flexible film is calculated by inversion.

7. The method for measuring the elastic modulus of flexible thin films based on electromagnetic drive according to claim 6, characterized in that, In step S3, while keeping the magnetic field strength constant, multiple sets of electromagnetic loading with different intensities are achieved by changing the current magnitude, and multiple sets of displacement data are obtained accordingly in step S4. In step S5, the error function is jointly constructed using the multiple sets of displacement data for inversion calculation.

8. The method for measuring the elastic modulus of flexible thin films based on electromagnetic drive according to claim 6, characterized in that, A parametric finite element model of the composite beam, including the base beam, microchannel, liquid metal and flexible film, is established; a parameter space including current, magnetic field strength, geometric dimensions of each component and material modulus is set, and a large number of numerical calculations are performed by changing the parameters to obtain the deflection at the measuring point position under different parameter combinations; The calculated data is dimensionless, and the dimensionless scaling law relationship is obtained by fitting.

9. The method for measuring the elastic modulus of flexible thin films based on electromagnetic drive according to claim 6, characterized in that, The inversion calculation in step S5 specifically involves: constructing an error function between the theoretically predicted displacement and the experimentally measured displacement based on the scaling law, and using the gradient descent method or the least squares method optimization algorithm to solve for the elastic modulus of the flexible film that minimizes the error function.

10. A composite beam structure for use in the apparatus of claim 1 or the method of claim 6, characterized in that, include: The base beam is made of polymer material and has clamping areas at both ends for fixing. Microchannels are embedded inside the base beam along its length, and the microchannels are filled with conductive liquid metal. A flexible film attached to the upper surface of the base beam; The microchannel is connected to an external current controller via a wire.

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