Elastic modulus measuring method and device based on electric field force driving

Abstract

The invention discloses an elastic modulus measuring method and device based on electric field force driving, and relates to the technical field of elastic modulus analysis and testing, and the elastic modulus measuring method comprises the following steps: (1) measuring the boundary dimension of a sample; (2) measuring the distance between the sample and the electrode plate; (3) driving the sample to deform through electric field force, so that the sample and the electrode plate are attracted; recording pull-in voltage when the sample is pulled in with the electrode plate; and (4) measuring the elasticity modulus of the sample according to the relationship among the boundary dimension, the spacing and the pull-in voltage of the sample. The method is simple in measurement process, shorter in measurement time and less in sample loss.

Description

Technical Field

[0001] The invention relates to the technical field of elastic modulus analysis and testing, and in particular to an elastic modulus measurement method and device based on electric field force driving. Background Art

[0002] The elastic modulus is a physical quantity that characterizes the material's ability to resist elastic deformation and is a key factor in calculating structural stiffness, stress and strain distribution, seismic resistance and other parameters. By selecting the right material and its elastic modulus, the design of the structure can be optimized to ensure that the structure has sufficient stiffness and stability while meeting functional requirements.

[0003] At present, the main methods for measuring the elastic modulus of materials are static stretching method and bending measurement method. The static stretching method calculates the elastic modulus through Hooke's law. The static stretching method is suitable for metal materials, composite materials, etc., but it is not suitable for some brittle materials. A large number of samples are required for measurement, the test time is long, and the sample clamping is relatively troublesome, requiring a strain extensometer for clamping. The bending measurement method measures the deflection and load of the beam through the three-point bending method or the four-point bending method to calculate the elastic modulus. The static stretching method is suitable for materials such as thin plates, which will be affected by factors such as the fulcrum position and loading method. It requires the consumption of samples and the test time is also long. The above methods are all lossy measurements, which cause more loss to the samples, and the measurement process is complicated and the measurement time is long. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned problems and provide a method for measuring the elastic modulus driven by electric field force, which has a simple measurement process, a shorter measurement time and less loss to the sample.

[0005] Another object of the present invention is to provide an elastic modulus measurement device driven by electric field force.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for measuring elastic modulus driven by electric field force comprises the following steps:

[0008] (1) Measure the dimensions of the specimen;

[0009] (2) Measure the distance between the sample and the electrode plate;

[0010] (3) driving the sample to deform by electric field force so that the sample and the electrode plate are attracted to each other; recording the attraction voltage when the sample and the electrode plate are attracted to each other;

[0011] (4) Measure the elastic modulus of the sample based on the relationship between the sample's dimensions, spacing, and pull-in voltage.

[0012] In a preferred embodiment of the present invention, in step (2), the sample is placed parallel to a fixed electrode plate, and the distance between the sample and the electrode plate is measured.

[0013] Preferably, in step (3), one end of the sample is a fixed end and the other end of the sample is a free end; a DC voltage is applied between the sample and the electrode plate, the sample and the electrode plate will have equal amounts of opposite charges, and the sample is subjected to the electric field force applied by the electrode plate, which drives the sample to bend and deform downward, so that the sample and the electrode plate are attracted.

[0014] Preferably, the external dimensions of the sample to be measured include the length and thickness of the sample. In step (4), the elastic modulus is calculated as follows:

[0015]

[0016] Where, E represents the elastic modulus of the sample, ε represents the dielectric constant, l represents the length of the sample, h represents the thickness of the sample; d represents the distance between the sample and the electrode plate; U cr Expressed as the pull-in voltage.

[0017] Preferably, in step (4), a calculation formula for the elastic modulus is obtained based on the relationship between the outer dimensions of the sample, the electric field force and the deformation deflection.

[0018] Furthermore, according to the outer dimensions of the sample, including the width of the sample; according to the relationship between the outer dimensions of the sample, the electric field force and the deformation deflection, the specific calculation steps of the calculation formula of the elastic modulus are obtained as follows:

[0019] For a specimen with one end fixed and the other end free, the deflection is obtained by the pure bending deformation equation of the beam. The deflection is related to the length of the specimen, the width of the specimen, the height of the specimen, the load per unit length, the elastic modulus of the specimen, and the horizontal distance from the fixed end. The maximum deflection is the deflection of the farthest free end.

[0020] The DC voltage between the sample and the electrode plate gradually increases from zero, and the sample will bend downward under the electric field distribution load, and the deflection increases with the increase of the DC voltage; at this time, the sample's resilience and the electric field force are balanced; the electric field force is obtained according to the dielectric constant, the area facing the sample and the electrode plate, the DC voltage between the sample and the electrode plate, and the distance between the sample and the electrode plate;

[0021] After the sample is bent and deformed, the distance between the sample and the electrode plate changes until the DC voltage increases to a certain level, at which time the sample will quickly attract the electrode plate. At this time, the deflection is equal to the distance between the sample and the electrode plate measured in step (2). The deflection is regarded as a function of the DC voltage, thereby obtaining the calculation formula of the elastic modulus.

[0022] An elastic modulus measuring device driven by electric field force comprises an insulating base, an electrode plate fixedly arranged on the insulating base, a DC voltage-stabilized power supply box, a voltage controller arranged on the DC voltage-stabilized power supply box, and a voltage measuring device; a clamping port for clamping one end of a sample is provided on the side of the DC voltage-stabilized power supply box, and the end of the sample located at the clamping port is a fixed end; the voltage controller is used to adjust the DC voltage between the sample and the electrode plate, and the voltage measuring device is used to read the DC voltage between the sample and the electrode plate.

[0023] The working principle of the elastic modulus measurement device driven by electric field force is as follows:

[0024] First, measure the outer dimensions of the sample, specifically the length, width and thickness (i.e., height) of the sample; then, place the fixed end of the sample in the clamping mouth for fixation; then, roughly estimate the order of magnitude of the elastic modulus of the sample, adjust the distance between the sample and the electrode plate, and select a roughly appropriate distance based on the DC voltage range of the DC regulated power supply box; then, slowly increase the DC voltage, and the sample bends and deforms downward until the sample and the electrode plate are attracted. The voltage measuring device will record the DC voltage at this time, which is the attraction voltage. At the same time, the DC regulated power supply box will quickly cut off the power to protect the sample; finally, based on the length, width, thickness, distance between the sample and the electrode plate, and the attraction voltage of the sample, the elastic modulus of the sample can be obtained through the calculation formula of the elastic modulus.

[0025] Preferably, the DC regulated power supply box is provided with a precision micrometer screw for adjusting the distance between the sample and the electrode plate. In the above structure, the adjustment accuracy of the precision micrometer screw is micron level, and the distance between the sample and the electrode plate is adjusted by the precision micrometer screw with high accuracy.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The elastic modulus measurement method based on electric field force driving in the present invention drives the sample to deform by the electric field force, so that the sample and the electrode plate are attracted, and the corresponding attraction voltage is measured. The elastic modulus of the sample is measured according to the relationship between the sample's outer dimensions, spacing and attraction voltage; the measurement process is simple, the measurement time is shorter, and the loss to the sample is less.

[0028] 2. The elastic modulus measurement method based on electric field force driving in the present invention provides a method for measuring elastic modulus, which is an important supplement to the method for measuring the elastic modulus of materials.

[0029] 3. The elastic modulus measuring device driven by electric field force in the present invention is also very simple and compact in structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the three-dimensional structure of one embodiment of an elastic modulus measurement device driven by electric field force in the present invention.

[0031] Figure 2 It is a front view of the elastic modulus measuring device in the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0033] Example 1

[0034] See also Figure 1-Figure 2 This embodiment discloses a method for measuring elastic modulus driven by electric field force, comprising the following steps:

[0035] (1) Measure the dimensions of sample 1;

[0036] (2) measuring the distance between the sample 1 and the electrode plate 2;

[0037] (3) driving the sample 1 to deform by the electric field force so that the sample 1 and the electrode plate 2 are attracted; recording the attraction voltage when the sample 1 and the electrode plate 2 are attracted; the attraction voltage is the DC voltage when the sample 1 and the electrode plate 2 are attracted;

[0038] (4) Based on the relationship between the sample's dimensions, spacing, and pull-in voltage, measure the elastic modulus of sample 1.

[0039] See also Figure 1-Figure 2 In step (2), the sample 1 is placed parallel to the fixed electrode plate 2, and the distance between the sample 1 and the electrode plate 2 is measured.

[0040] See also Figure 1-Figure 2 In step (3), one end of sample 1 is a fixed end, and the other end of sample 1 is a free end; a DC voltage is applied between sample 1 and electrode plate 2, and sample 1 and electrode plate 2 will have equal amounts of opposite charges. Sample 1 is subjected to the electric field force applied by electrode plate 2, driving sample 1 to bend and deform downward, so that sample 1 and electrode plate 2 are attracted.

[0041] See also Figure 1-Figure 2 , measure the dimensions of the sample 1 including the length and thickness of the sample 1, in step (4), the elastic modulus is calculated as:

[0042]

[0043] Where, E represents the elastic modulus of sample 1, ε represents the dielectric constant, l represents the length of sample 1, h represents the thickness of sample 1; d represents the distance between sample 1 and electrode plate 2; U cr Expressed as the pull-in voltage.

[0044] See also Figure 1-Figure 2 , according to the outer dimensions of sample 1, it also includes the width of sample 1; in step (4), according to the relationship between the outer dimensions of sample 1, the electric field force and the deformation deflection, the calculation formula of the elastic modulus is obtained.

[0045] The specific measurement principle is:

[0046] After the non-insulated sample 1 is made into a suitable size, the outer dimensions of the sample 1, including the length, width and thickness, are measured; the sample 1 is placed parallel to the electrode plate 2, and a DC voltage is applied between the sample 1 and the electrode plate 2. At this time, the sample 1 and the electrode plate 2 will have equal amounts of opposite charges, and the sample 1 is subjected to the electric field force applied by the electrode plate 2. The calculation formula of the electric field force is:

[0047]

[0048] Among them, F represents the electric field force; ε represents the dielectric constant; S is the facing area between the sample 1 and the electrode plate 2; U represents the DC voltage between the sample 1 and the electrode plate 2; d represents the distance between the sample 1 and the electrode plate 2.

[0049] For specimen 1, one end of which is fixed and the other end is free, the deflection is obtained by the pure bending deformation equation of the beam. The pure bending deformation equation is:

[0050]

[0051] Among them, w represents the deflection of specimen 1, q represents the load per unit length, E represents the elastic modulus of specimen 1, x represents the horizontal distance from the fixed end, l is the length of specimen 1, I is the moment of inertia of the cross section about the neutral plane, and the calculation formula of the moment of inertia of the cross section about the neutral plane is:

[0052]

[0053] Wherein, b represents the width of sample 1, and h represents the thickness of sample 1.

[0054] The maximum deflection is the deflection of the farthest free end, that is, when x=l, substituting it into the pure bending deformation equation, the calculation formula for the maximum deflection can be obtained:

[0055]

[0056] Among them, w m Expressed as the maximum deflection.

[0057] From the above formula, it can be seen that the maximum deflection is proportional to the load per unit length q. In this case, the calculation formula for the load per unit length of sample 1 is:

[0058]

[0059] Wherein, F represents the electric field force; q represents the load per unit length; l is the length of sample 1.

[0060] The DC voltage between the sample 1 and the electrode plate 2 gradually increases from zero, and the sample 1 will bend downward under the electric field distribution load, and the deflection increases with the increase of the DC voltage; at this time, the resilience of the sample 1 is balanced with the electric field force, that is:

[0061] F=F 弹 =k m w m

[0062] Where F represents the electric field force, F 弹 Expressed as the rebound force of sample 1, w m Expressed as the maximum deflection, k m It is expressed as the equivalent stiffness at x = l; by substituting the calculation formula of the maximum value and the calculation formula of the load per unit length, the calculation formula of the equivalent stiffness at x = l can be obtained, and the calculation formula is:

[0063]

[0064] After the bending deformation of the sample 1, the distance between the sample 1 and the electrode plate 2 is no longer a constant value d, that is, the distance between the sample 1 and the electrode plate 2 is variable, and the variable distance is dw(x), where w(x) is the deflection at the distance x from the fixed end. Therefore, the calculation formula of the electric field force F becomes:

[0065]

[0066] Combining the calculation formula of the balance between the rebound force and the electric field force, it can be deduced that:

[0067]

[0068] When the DC voltage U increases to a certain level, the sample 1 will quickly attract the electrode plate 2. The DC voltage U at this time is the attraction voltage U cr , also called critical pickup voltage, pickup voltage U cr The calculation process is as follows:

[0069] When the DC voltage U increases to a certain extent, the deflection w quickly becomes the spacing d, that is, the deflection w is equal to the spacing d between the sample 1 and the electrode plate 2 measured in step (2), and the deflection w is regarded as a function of the DC voltage U. cr Mathematically, it should be a maximum point, so dw / dU tends to positive infinity, that is, the stationary point (w cr ,U cr )satisfy:

[0070]

[0071] Find:

[0072]

[0073] And meet

[0074]

[0075] Will Substitution In combination with the formula We can get:

[0076]

[0077] According to the above formula, the pull-in voltage U cr It is related to the elastic modulus E of sample 1, the length l and the thickness h of sample 1, that is, the calculation formula of the elastic modulus is:

[0078]

[0079] That is to say, after knowing the geometric dimensions (outer dimensions) l and h of the sample 1, it is only necessary to measure the pull-in voltage U cr , the elastic modulus E can be measured.

[0080] Example 2

[0081] See also Figure 1-Figure 2 The present embodiment discloses an elastic modulus measuring device driven by an electric field force, and the elastic modulus measuring device is used to implement the elastic modulus measuring method as described in Example 1, and the elastic modulus measuring device includes an insulating base 3, an electrode plate 2 fixedly arranged on the insulating base 3, a DC voltage-stabilized power supply box 4, a voltage controller 5 arranged on the DC voltage-stabilized power supply box 4, and a voltage measuring device; the side of the DC voltage-stabilized power supply box 4 is provided with a clamping port for clamping one end of a sample 1, and the end of the sample 1 located at the clamping port is a fixed end; the voltage controller 5 is used to adjust the DC voltage between the sample 1 and the electrode plate 2, and the voltage measuring device is used to read the DC voltage between the sample 1 and the electrode plate 2.

[0082] See also Figure 1-Figure 2 The measurement process of the elastic modulus measurement device driven by electric field force is as follows:

[0083] (S1) measuring the dimensions of the sample 1, specifically measuring the length, width and thickness (i.e., height) of the sample 1;

[0084] (S2) placing the fixed end of the sample 1 in the clamping opening for fixing;

[0085] (S3) roughly estimating the order of magnitude of the elastic modulus of the sample 1, adjusting the distance between the sample 1 and the electrode plate 2, and selecting a roughly appropriate distance according to the DC voltage range of the DC regulated power supply box 4; and measuring the distance between the sample 1 and the electrode plate 2;

[0086] (S4) Slowly increase the DC voltage, and the sample 1 bends and deforms downward until the sample 1 and the electrode plate 2 are attracted. The voltage measuring device will record the DC voltage at this time, which is the attraction voltage. At the same time, the DC regulated power supply box 4 is quickly powered off to protect the sample 1;

[0087] (S5) The elastic modulus of the sample 1 can be obtained according to the length, width, thickness of the sample 1, the distance between the sample 1 and the electrode plate 2, and the pull-in voltage by using the elastic modulus calculation formula.

[0088] See also Figure 1-Figure 2 The DC voltage-stabilized power supply box 4 is provided with a precision micrometer screw 6 for adjusting the distance between the sample 1 and the electrode plate 2. Specifically, the height of the sample 1 can be adjusted, and then the distance between the sample 1 and the electrode plate 2 can be adjusted. In the above structure, the adjustment accuracy of the precision micrometer screw 6 is at the micron level. The distance between the sample 1 and the electrode plate 2 is adjusted by the precision micrometer screw 6 with high accuracy.

[0089] See also Figure 1-Figure 2 The electrode plate 2 is nested on the insulating base 3, and the DC regulated power supply box 4 is also arranged on the insulating base 3, located next to one end of the electrode plate 2. After the fixed end of the sample 1 is placed in the clamping mouth for fixing, the sample 1 is parallel to the electrode plate 2.

[0090] The dimensions of the sample 1 in this embodiment are: length l = 20 mm, width b = 3 mm, thickness h = 1 mm; the distance between the sample 1 and the electrode plate 2 is d = 5 μm, and the pull-in voltage U cr =80V, and the elastic modulus can be calculated from the elastic modulus calculation formula to obtain the elastic modulus E=163GPa.

[0091] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for measuring elastic modulus driven by electric field force, characterized in that: The following steps are involved: (1) Measure the dimensions of the specimen; (2) Measure the distance between the sample and the electrode plate; (3) driving the sample to deform by electric field force so that the sample and the electrode plate are attracted to each other; recording the attraction voltage when the sample and the electrode plate are attracted to each other; (4) Measure the elastic modulus of the sample based on the relationship between the sample's dimensions, spacing, and pull-in voltage.

2. The elastic modulus measurement method based on electric field force driving according to claim 1 is characterized in that: In step (2), the sample is placed parallel to a fixed electrode plate, and the distance between the sample and the electrode plate is measured.

3. The elastic modulus measurement method based on electric field force driving according to claim 2 is characterized in that: In step (3), one end of the sample is a fixed end, and the other end of the sample is a free end; a DC voltage is applied between the sample and the electrode plate, and the sample and the electrode plate will have equal amounts of opposite charges. The sample is subjected to the electric field force applied by the electrode plate, which drives the sample to bend downward, so that the sample and the electrode plate are attracted.

4. A method for measuring elastic modulus driven by electric field force according to claim 3, characterized in that: The external dimensions of the measured sample include the length and thickness of the sample. In step (4), the elastic modulus is calculated as follows: Where, E represents the elastic modulus of the sample, ε represents the dielectric constant, l represents the length of the sample, h represents the thickness of the sample; d represents the distance between the sample and the electrode plate; U cr Expressed as the pull-in voltage.

5. A method for measuring elastic modulus driven by electric field force according to claim 4, characterized in that: In step (4), a calculation formula for the elastic modulus is obtained based on the relationship between the outer dimensions of the sample, the electric field force and the deformation deflection.

6. An elastic modulus measurement device driven by electric field force, characterized in that: The elastic modulus measuring device is used to implement the elastic modulus measuring method as described in any one of claims 1 to 5, and the elastic modulus measuring device includes an insulating base, an electrode plate fixedly arranged on the insulating base, a DC voltage-stabilized power supply box, a voltage controller arranged on the DC voltage-stabilized power supply box, and a voltage measuring device; the side of the DC voltage-stabilized power supply box is provided with a clamping port for clamping one end of the sample, and the end of the sample located at the clamping port is a fixed end; the voltage controller is used to adjust the DC voltage between the sample and the electrode plate, and the voltage measuring device is used to read the DC voltage between the sample and the electrode plate.

7. The elastic modulus measuring device driven by electric field force according to claim 6, characterized in that: The DC voltage-stabilized power supply box is provided with a precision screw micrometer for adjusting the distance between the sample and the electrode plate.

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