Optimization method suitable for uniformizing piezoelectric layer of folded piezoelectric vibrator

Abstract

The invention discloses an optimization method suitable for uniformizing a piezoelectric layer of a folded piezoelectric vibrator. The optimization method comprises the following steps: constructing a finite element model of the folded piezoelectric vibrator through finite element simulation software; performing modal analysis and harmonic response analysis on the finite element model of the folded piezoelectric vibrator through finite element simulation software to obtain equivalent stress data of a piezoelectric layer; based on the piezoelectric layer equivalent stress data, obtaining a piezoelectric layer equivalent stress distribution uniformity degree model through calculation; based on the relative standard deviation of the piezoelectric layer equivalent stress data, optimization design is carried out on the folded piezoelectric vibrator, and structural parameters with uniform piezoelectric layer equivalent stress distribution are obtained. According to the invention, equivalent stress distribution of the piezoelectric layer of the folded piezoelectric vibrator can be optimized, and the utilization efficiency of the piezoelectric plate is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of piezoelectric vibration energy collection, and in particular relates to an optimization method suitable for homogenizing a piezoelectric layer of a folded piezoelectric vibrator. Background Art

[0002] In recent years, with the rapid development of integrated circuits and wireless communication technology, the development of wireless sensor devices has become increasingly mature. It has broad application prospects in industrial control, smart home, environmental monitoring and other fields, and has been used in some fields and plays an important role. And with the rapid development of low-power electronic technology and self-powered wireless sensor networks in engineering, vibration energy harvesting has been widely used in engineering application fields. Vibration energy harvesting can not only convert vibration energy into electrical energy to power low-power electronic devices, but also reduce harmful vibrations of instruments and equipment. At present, the commonly used vibration energy harvesting technologies can be mainly divided into electrostatic, electromagnetic, piezoelectric, magnetostrictive and their hybrid types according to the conversion principle. Among them, piezoelectric vibration energy harvesting technology has been widely used in various engineering fields because of its simple structure, high output voltage, and self-powered demand without external power supply. At present, the piezoelectric sheets used in the widely used piezoelectric energy harvesters mostly adopt rectangular structures, but due to the uneven stress distribution of the rectangular structure in its vibration mode, the utilization efficiency of the piezoelectric sheets is limited. Therefore, it is necessary to improve the uniformity of the equivalent stress distribution of the piezoelectric vibrator piezoelectric sheet during bending vibration. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes an optimization method suitable for homogenizing the piezoelectric layer of a folded piezoelectric vibrator, which can optimize the equivalent stress distribution of the piezoelectric layer of the folded piezoelectric vibrator and improve the utilization efficiency of the piezoelectric sheet.

[0004] To achieve the above object, the present invention provides an optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator, comprising:

[0005] Construct a finite element model of the folded piezoelectric vibrator through finite element simulation software;

[0006] Performing modal analysis and harmonic response analysis on the finite element model of the folded piezoelectric vibrator by finite element simulation software to obtain equivalent stress data of the piezoelectric layer;

[0007] Based on the piezoelectric layer equivalent stress data, a piezoelectric layer equivalent stress distribution uniformity model is obtained by calculation;

[0008] Based on the relative standard deviation of the equivalent stress data of the piezoelectric layer, the folded piezoelectric vibrator is optimized and designed to obtain structural parameters with uniform distribution of the equivalent stress of the piezoelectric layer.

[0009] Furthermore, the method for constructing a folded piezoelectric vibrator finite element model includes:

[0010] In the process of constructing the folded piezoelectric vibrator finite element model, the piezoelectric sheet and the elastic beam are connected by bonding, and the bending parts of the folded piezoelectric vibrator finite element model structure are chamfered.

[0011] Furthermore, in the finite element model of the folded piezoelectric vibrator, material properties are controlled by using engineering data, and the piezoelectric materials are polarized along the thickness direction.

[0012] Furthermore, the folded elastic matrix material of the folded piezoelectric vibrator finite element model is 304 stainless steel, and the piezoelectric material is lead zirconate titanate.

[0013] Furthermore, the stiffness coefficient matrix C, the piezoelectric stress constant matrix e and the dielectric constant matrix ε of the piezoelectric material are expressed as follows:

[0014]

[0015]

[0016]

[0017] Furthermore, the method for performing modal analysis on the folded piezoelectric vibrator finite element model includes:

[0018] Based on the folded piezoelectric vibrator finite element model, a block Lanczos method is selected to extract a preset number of modes;

[0019] The extracted modes are analyzed to obtain the modal analysis results.

[0020] Furthermore, the method for performing harmonic response analysis on the folded piezoelectric vibrator finite element model includes:

[0021] The first-order natural frequency of the piezoelectric vibrator is selected, a simple harmonic load of the first-order frequency is applied to the whole, a harmonic response analysis of the piezoelectric vibrator is performed, and the harmonic response analysis results are obtained.

[0022] Furthermore, the piezoelectric layer equivalent stress distribution uniformity model is expressed as:

[0023]

[0024] Among them, RSD is the uniformity model of the equivalent stress distribution of the piezoelectric layer, S is the standard deviation of the equivalent stress data of the piezoelectric layer, is the average value of the corresponding piezoelectric layer equivalent stress data, x i is the piezoelectric layer equivalent stress data set, and n is the number of data.

[0025] Technical effect of the invention: The present invention discloses an optimization method suitable for homogenizing the piezoelectric layer of a folded piezoelectric vibrator, which overcomes the problems of uneven stress distribution in the vibration mode and limited utilization efficiency of the piezoelectric sheet in the prior art using a rectangular structure, and can optimize the equivalent stress distribution of the piezoelectric layer of the folded piezoelectric vibrator and improve the utilization efficiency of the piezoelectric sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0027] Figure 1 A schematic flow chart of an optimization method for homogenizing a piezoelectric layer of a folded piezoelectric vibrator according to an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the implementation steps of homogenizing the piezoelectric layer of a folded piezoelectric vibrator according to an embodiment of the present invention;

[0029] Figure 3 In the embodiments of the present invention, the length and width of the piezoelectric sheet are used as single variables to calculate the relative standard deviation of the equivalent stress of the piezoelectric layer of the piezoelectric vibrator with different lengths and widths under the first-order modal vibration mode. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0032] like Figure 1-2 As shown, this embodiment provides an optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator, including:

[0033] Step 1, determine the overall structural dimensions of the folded piezoelectric vibrator and establish a finite element model;

[0034] The finite element model of the folded piezoelectric vibrator is established using the finite element simulation software ANSYS;

[0035] The finite element model of the folded piezoelectric vibrator, in order to simplify the structure, the bonding layer between the piezoelectric sheet and the elastic beam can be ignored in the modeling process, and the connection method is selected as bonding;

[0036] In order to reduce the stress concentration of the structure, the bending parts of the model structure are rounded.

[0037] In ANSYS software, the material properties are controlled by Engineering Data, and the piezoelectric materials are polarized along the thickness direction (i.e., the Z direction);

[0038] The materials of each component of the model are assigned. The folding elastic matrix material is 304 stainless steel, which has a good elastic stiffness coefficient, and the piezoelectric material is lead zirconate titanate (PZT-51) with a high piezoelectric coefficient.

[0039] Optionally, the stiffness coefficient matrix C, the piezoelectric stress constant matrix e, and the dielectric constant matrix ε of the piezoelectric material PZT-51 are as follows:

[0040]

[0041]

[0042]

[0043] Step 2, using ANSYS finite element simulation software to perform modal analysis and harmonic response analysis on the folded piezoelectric vibrator;

[0044] Perform modal analysis on the piezoelectric vibrator. Optionally, the mode extraction method uses the block Lanczos method with fast convergence speed, i.e., "Block Lanczos", and the number of extractions is set to 6;

[0045] The natural frequencies of each mode of the piezoelectric vibrator are mainly affected by the geometric structure of the device. Considering the complexity of environmental factors and the fact that the environmental damping has a relatively small effect on the natural frequency of the piezoelectric vibrator compared to the device structure itself, and in order to speed up the convergence, the simulation does not take environmental damping into consideration. Therefore, the results of the modal analysis are the natural frequencies and vibration modes under ideal conditions.

[0046] The first-order natural frequency of the piezoelectric vibrator is selected, and a simple harmonic load of the first-order frequency is applied to the whole body to solve the harmonic response.

[0047] Step 3, extracting the stress value on the piezoelectric layer and calculating its relative standard deviation, so as to evaluate the uniformity of stress distribution when the piezoelectric sheet of the folded piezoelectric vibrator is deformed;

[0048] A path is established for the piezoelectric layer of the model, and the equivalent stress value of the piezoelectric piece during bending vibration in the path is extracted.

[0049] The model of uniformity of equivalent stress distribution of piezoelectric layer is:

[0050]

[0051] S is the standard deviation of the equivalent stress data of the piezoelectric layer, is the average value of the corresponding piezoelectric layer equivalent stress data, x i is the piezoelectric layer equivalent stress data set, and n is the number of data.

[0052] Step 4, complete the optimization design: change the size of the folded piezoelectric vibrator, perform modal analysis and harmonic response analysis, extract the equivalent stress value of the piezoelectric layer, and calculate the relative standard deviation of the piezoelectric layer of the folded piezoelectric vibrator under this size. The smaller the value, the more uniform the distribution of the equivalent stress of the piezoelectric layer, which means that the utilization rate of the piezoelectric material is higher, and the piezoelectric vibrator collects and converts more electrical energy;

[0053] Use finite element simulation software to perform modal and harmonic response simulation and extract equivalent stress data of the piezoelectric layer;

[0054] Based on the data, a model of the uniformity of the equivalent stress distribution of the piezoelectric layer is calculated;

[0055] Based on the relative standard deviation of the equivalent stress data of the piezoelectric layer, the folded piezoelectric vibrator is optimized to obtain structural parameters with more uniform distribution of the equivalent stress of the piezoelectric layer, thereby improving the utilization efficiency of the piezoelectric sheet.

[0056] Figure 3 In order to implement the method, the length and width of the piezoelectric sheet are taken as single variables, and the relative standard deviation of the equivalent stress of the piezoelectric layer of the piezoelectric vibrator with different lengths and widths under the first-order modal vibration mode is calculated. The smaller the relative standard deviation (RSD) of the equivalent stress is, the more uniform the stress distribution of the piezoelectric layer is, and the higher the utilization rate of the piezoelectric material is.

[0057] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator, characterized in that: include: Construct a finite element model of the folded piezoelectric vibrator through finite element simulation software; Performing modal analysis and harmonic response analysis on the finite element model of the folded piezoelectric vibrator by finite element simulation software to obtain equivalent stress data of the piezoelectric layer; Based on the piezoelectric layer equivalent stress data, a piezoelectric layer equivalent stress distribution uniformity model is obtained by calculation; Based on the relative standard deviation of the equivalent stress data of the piezoelectric layer, the folded piezoelectric vibrator is optimized and designed to obtain structural parameters with uniform distribution of the equivalent stress of the piezoelectric layer.

2. The optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator as claimed in claim 1, characterized in that: The method of constructing the finite element model of the folded piezoelectric vibrator includes: In the process of constructing the folded piezoelectric vibrator finite element model, the piezoelectric sheet and the elastic beam are connected by bonding, and the bending parts of the folded piezoelectric vibrator finite element model structure are chamfered.

3. The optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator as claimed in claim 1, characterized in that: In the folded piezoelectric vibrator finite element model, material properties are controlled by engineering data, and the piezoelectric materials are polarized along the thickness direction.

4. The optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator as claimed in claim 1, characterized in that: The folded elastic matrix material of the folded piezoelectric vibrator finite element model is 304 stainless steel, and the piezoelectric material is lead zirconate titanate.

5. The optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator as claimed in claim 4, characterized in that: The stiffness coefficient matrix C, piezoelectric stress constant matrix e and dielectric constant matrix ε of the piezoelectric material are expressed as follows:

6. The optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator according to claim 1, characterized in that: The method for performing modal analysis on the folded piezoelectric vibrator finite element model comprises: Based on the folded piezoelectric vibrator finite element model, a block Lanczos method is selected to extract a preset number of modes; The extracted modes are analyzed to obtain the modal analysis results.

7. The optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator according to claim 1, characterized in that: The method for performing harmonic response analysis on the folded piezoelectric vibrator finite element model comprises: The first-order natural frequency of the piezoelectric vibrator is selected, a simple harmonic load of the first-order frequency is applied to the whole, a harmonic response analysis of the piezoelectric vibrator is performed, and the harmonic response analysis results are obtained.

8. The optimization method for homogenizing the piezoelectric layer of a folded piezoelectric vibrator as claimed in claim 1, characterized in that: The piezoelectric layer equivalent stress distribution uniformity model is expressed as: Among them, RSD is the uniformity model of the equivalent stress distribution of the piezoelectric layer, S is the standard deviation of the equivalent stress data of the piezoelectric layer, is the average value of the corresponding piezoelectric layer equivalent stress data, x i is the piezoelectric layer equivalent stress data set, and n is the number of data.

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