Flexible piezoelectric composite material parameter optimization analysis method and system, medium and terminal

Abstract

The invention relates to the technical field of flexible piezoelectric composite materials, in particular to a flexible piezoelectric composite material parameter optimization analysis method and system, a medium and a terminal. The method comprises a mesoscopic model building step, a piezoelectric ceramic fiber parameter analysis step, an interdigital electrode parameter analysis step, a macroscopic model building step and a parameter optimization step. The influence of the parameters of the flexible piezoelectric composite material on the performance of the flexible piezoelectric composite material is analyzed through combined modeling analysis on a mesoscale and a macroscale and based on an action mechanism level, so that the parameters of the flexible piezoelectric composite material are optimized and adjusted from multiple scales, and the performance of the flexible piezoelectric composite material is effectively improved. And a reliable reference basis is provided for preparation of the flexible piezoelectric composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric composite materials, and in particular to a method and system, a medium and a terminal for optimizing and analyzing parameters of a flexible piezoelectric composite material. Background Art

[0002] Flexible Piezoelectric Composite (FPC) is a new type of piezoelectric composite material that combines piezoelectric materials with flexible substrate materials in a certain proportion and structure. It has the electrical properties of piezoelectric materials and the mechanical properties of flexible substrate materials. FPC mainly includes piezoelectric ceramics, interdigital electrodes and flexible polymer matrix. FPC can be applied to surfaces of structures with different curvatures because of its conversion characteristics of piezoelectric ceramic electromechanical coupling and greater flexibility. In addition, it also has the advantages of high strain energy density, directional drive, bendability, durability, etc. It is suitable for vibration monitoring and vibration control of curved structures of spacecraft, as well as other wearable devices, biomedical devices and other fields, and has great development prospects.

[0003] At present, many existing technologies only describe the preparation process of FPC, and do not provide detailed descriptions of the specific size parameters, component parameters and other designs of each structure. However, the inventors found that different designs of various parameters of FPC will affect the flexibility, bendability, driving effect, polarization effect, electric field distribution and other performance of FPC, and thus affect the vibration sensing-actuation effect of FPC, which is important for the reliability and safety of vibration monitoring and vibration control applied to curved structures of spacecraft. In particular, when the application environment is different and the curvature of the controlled structural parts is different, the requirements for the vibration sensing-actuation effect and flexibility of FPC are also different. Therefore, it is of great significance to optimize the design of FPC parameters according to application requirements. Summary of the invention

[0004] In order to solve the above-mentioned shortcomings in the prior art of FPC performance, the present invention provides a parameter optimization analysis method for a flexible piezoelectric composite material, comprising the following steps: Mesoscopic model establishment step: at the mesoscopic scale, a representative volume unit RVE model of the FPC is established based on the initial geometric parameters of the FPC, and a structural model of the FPC is constructed, wherein the structural model at least includes piezoelectric ceramic fibers, a polymer matrix, and interdigital electrodes; A piezoelectric ceramic fiber parameter analysis step: based on the representative volume unit RVE model, adjusting the volume fraction of the piezoelectric ceramic fiber to calculate the deformation of the RVE model under a preset voltage under different parameters, thereby obtaining the relationship between the volume fraction of the piezoelectric ceramic fiber and the piezoelectric constant; The interdigital electrode parameter analysis step: based on the representative volume unit RVE model, adjusting the width of the interdigital electrode and the spacing between adjacent interdigital electrodes to calculate the electric field distribution between adjacent interdigital electrodes under the action of the preset voltage, thereby obtaining the relationship between the width of the interdigital electrode, the spacing between adjacent interdigital electrodes and the polarization effect; Macro model establishment step: On a macro scale, a homogenized model of the FPC is established, and the flexibility and piezoelectric constant of the FPC are calculated according to a mixing rule to obtain a relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility of the FPC and the piezoelectric constant of the FPC; Parameter optimization step: According to the preset flexibility range requirements and piezoelectric constant requirements of the FPC, the volume fraction of the piezoelectric ceramic fiber, the width of the interdigital electrode and the spacing between adjacent interdigital electrodes are derived in combination with the relationship between the width of the interdigital electrode, the spacing between adjacent interdigital electrodes and the polarization effect, and the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility and piezoelectric constant of the FPC.

[0005] In some embodiments, in the mesoscopic model establishment step, the structural model at least includes piezoelectric ceramic fibers, a polymer matrix and interdigitated electrodes; the polymer matrix is ​​respectively located on opposite sides of the piezoelectric ceramic along the X direction to form a piezoelectric active layer with the piezoelectric ceramic, and the interdigitated electrodes are respectively located on opposite sides of the piezoelectric active layer along the Z direction, wherein the X direction is perpendicular to the Z direction; the structural model includes a d31-type structural model and a d33-type structural model with different polarization types; wherein the polarization type of the d31-type structural model is transverse polarization with a polarization direction perpendicular to the surface of the flexible piezoelectric composite material sheet, and the positive and negative electrodes of the interdigitated electrodes in the d31-type structural model are respectively located on the opposite surfaces of the flexible piezoelectric composite material sheet; the polarization type of the d33-type structural model is longitudinal polarization with a polarization direction parallel to the surface of the flexible piezoelectric composite material sheet, and the positive and negative electrodes of the interdigitated electrodes in the d33-type structural model are both located on the opposite surfaces of the flexible piezoelectric composite material sheet.

[0006] In some embodiments, the volume fraction of the piezoelectric ceramic fiber is satisfy: ; In the formula, is the width of the piezoelectric ceramic fiber, is the width of the polymer matrix.

[0007] In some embodiments, the spacing between adjacent interdigital electrodes is between 0.5 and 1 mm, and the width of the interdigital electrodes is between 0.8 and 1.5 mm.

[0008] In some embodiments, in the interdigital electrode parameter analysis step, it also includes adjusting the width of the interdigital electrode, and performing mechanical simulation under a preset stress on the RVE model to obtain a relationship between the width of the interdigital electrode and the maximum stress in the RVE model; The parameter optimization step also includes determining the width of the interdigital electrode according to the flexibility range requirement, the piezoelectric constant requirement, the maximum stress in the RVE model, and the proportion of the uniform polarization region.

[0009] In some embodiments, in the macro model building step, the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility of the FPC and the piezoelectric constant of the FPC is represented by a piezoelectric constitutive equation characterizing the flexible piezoelectric composite material; The piezoelectric constitutive equation is expressed as:

[0010]

[0011] In the formula, It is expressed as the stiffness matrix of FPC under orthotropic conditions; It is represented as a piezoelectric coupling matrix; , , It is expressed as the normal stress of the piezoelectric active layer in the x-axis, y-axis, and z-axis; , , They represent the shear stress of the piezoelectric active layer in the x-axis, y-axis, and z-axis respectively; , , They are respectively represented as the positive strain of the piezoelectric active layer in the x-axis, y-axis, and z-axis, , , are respectively represented as the shear strain of the piezoelectric active layer in the x-axis, y-axis, and z-axis, , , They are respectively represented as the electric field strength of the x-axis, y-axis, and z-axis, , , They are represented as the electric displacements of the x-axis, y-axis, and z-axis respectively.

[0012] In some embodiments, the volume fraction of the piezoelectric ceramic fibers is between 70% and 85%.

[0013] In a second aspect, the present invention further provides a parameter optimization system for a flexible piezoelectric composite material, comprising: A mesoscopic model building module; used to establish a representative volume unit RVE model of the FPC based on the initial geometric parameters of the FPC at the mesoscopic scale, and to construct a structural model of the FPC, wherein the structural model at least includes piezoelectric ceramic fibers, a polymer matrix, and interdigital electrodes; A piezoelectric ceramic fiber parameter analysis module; used to adjust the volume fraction of the piezoelectric ceramic fiber based on the representative volume unit RVE model to calculate the deformation of the RVE model under a preset voltage under different parameters, and then obtain the relationship between the volume fraction of the piezoelectric ceramic fiber and the piezoelectric constant; An interdigital electrode parameter analysis module; used to adjust the width of the interdigital electrodes and the spacing between adjacent interdigital electrodes based on the representative volume unit RVE model to calculate the electric field distribution between adjacent interdigital electrodes under the action of the preset voltage, and then obtain the relationship between the width of the interdigital electrodes, the spacing between adjacent interdigital electrodes and the polarization effect; A macro model building module; used to build a homogenized model of the FPC on a macro scale, and calculate the flexibility and piezoelectric constant of the FPC according to a mixing rule to obtain the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility of the FPC and the piezoelectric constant of the FPC; A parameter optimization module; used to derive the volume fraction of the piezoelectric ceramic fiber, the width of the interdigital electrode and the spacing between adjacent interdigital electrodes according to the preset flexibility range requirements and piezoelectric constant requirements of the FPC, combined with the relationship between the width of the interdigital electrode, the spacing between adjacent interdigital electrodes and the polarization effect, and the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility and piezoelectric constant of the FPC.

[0014] In a third aspect, the present invention also provides a storage medium, which is a non-volatile storage medium or a non-transient storage medium, on which a computer program is stored, and when the computer program is run by a processor, the parameter optimization analysis method of the flexible piezoelectric composite material described in the above embodiment is executed.

[0015] In a fourth aspect, the present invention further provides a terminal comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor runs the computer program, it executes the parameter optimization analysis method of the flexible piezoelectric composite material as described in the above embodiment.

[0016] Based on the above, compared with the prior art, the parameter optimization analysis method of the flexible piezoelectric composite material provided by the present invention jointly models and analyzes the influence of the parameters of the flexible piezoelectric composite material on the performance based on the mechanism level, thereby optimizing and adjusting the parameters of the flexible piezoelectric composite material from multiple scales, so as to effectively improve the performance of the flexible piezoelectric composite material and provide a reliable reference basis for the preparation of flexible piezoelectric composite materials.

[0017] Other features and beneficial effects of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other beneficial effects of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. The positional relationships described in the drawings in the following description are based on the directions in which the components are drawn in the diagrams, unless otherwise specified.

[0019] Figure 1 A flow chart of the steps of a parameter optimization analysis method for a flexible piezoelectric composite material provided by an embodiment of the present invention; Figure 2a , Figure 2b They are schematic diagrams of the d31 type FPC structure model and the d33 type FPC structure model respectively; Figure 3a , Figure 3b The composition diagrams of the representative volume unit RVE models of d31-type FPC and d33-type FPC, respectively; Figure 4a , Figure 4b Schematic diagrams of the internal electric field distribution of d31 type FPC and d33 type FPC respectively; Figure 5a , Figure 5b Schematic diagrams of the relationship between the spacing between adjacent interdigital electrodes and the proportion of the uniform polarization area in d31-type FPC and d33-type FPC respectively; Figure 6a , Figure 6b Schematic diagrams of the relationship between the width of the interdigital electrodes and the proportion of the uniform polarization area in the d31 type FPC and the d33 type FPC; Figure 7 Schematic diagram of the relationship between the width of the interdigitated electrode and the maximum stress generated when an electric potential is applied; Figure 8a , Figure 8b Schematic diagram of the relationship between the volume fraction of piezoelectric ceramic fibers of d31-type FPC and d33-type FPC under the same electromechanical working conditions; Fig. 9 Schematic diagram of the relationship between the volume fraction of piezoelectric ceramic fibers and the Poisson's ratio of the FPC piezoelectric active layer; Fig.10 Schematic diagram of the relationship between the volume fraction of piezoelectric ceramic fibers and the flexibility of the FPC piezoelectric active layer. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be noted that all terms (including technical terms and scientific terms) used in the present invention have the same meanings as those generally understood by ordinary technicians in the field to which the present invention belongs, and should not be understood as limitations on the present invention; it should be further understood that the terms used in the present invention should be understood to have the same meanings as these terms in the context of this specification and in the relevant fields, and should not be understood in an idealized or overly formal sense, unless explicitly defined in this invention.

[0022] At present, there is no detailed description of the component ratio parameters and structural parameters of each component of the flexible piezoelectric composite material in the prior art. Therefore, in the preparation of FPC, the design is generally based on existing experience and the component parameters of the FPC cannot be optimized and adjusted according to application requirements. In addition, the existing model analysis method for FPC generally adopts a simplified macro model. However, it is difficult to intuitively examine the components and structural parameters of the FPC, and changing the components and structural parameters requires recalculating the constitutive equation of the simplified macro model and constructing a simplified model, which easily leads to problems such as complex calculations and large amount of calculations during the parameter design process.

[0023] In view of this, the present invention provides a parameter optimization analysis method for a flexible piezoelectric composite material to effectively solve the above problems. The technical solution of the present invention is described and illustrated in detail below in combination with different embodiments and drawings of the specification through a variety of specific implementation methods.

[0024] Embodiment 1 See also Figure 1 The parameter optimization analysis method of the flexible piezoelectric composite material provided in this embodiment includes the following steps: Mesoscopic model establishment step: at the mesoscopic scale, a representative volume unit RVE model of the FPC is established based on the initial geometric parameters of the FPC, and a structural model of the FPC is constructed, wherein the structural model at least includes piezoelectric ceramic fibers, a polymer matrix, and interdigital electrodes.

[0025] In specific implementation, according to the structural characteristics that the piezoelectric ceramic fibers, polymer matrix and interdigital electrodes inside the FPC are all arranged periodically, the embodiment of the present invention selects a micro unit including piezoelectric ceramic fibers, polymer matrix and interdigital electrodes to study the unit periodicity. The FPC can be regarded as a periodically arranged RVE array. The deformation and electric field distribution of the RVE model under certain voltage conditions are calculated to reflect the deformation and internal electric field distribution of the FPC. Therefore, the embodiment of the present invention establishes a representative volume unit RVE model of the FPC based on the initial geometric parameters of the FPC at the mesoscopic scale, and analyzes the influence of each parameter on the performance through the representative volume unit RVE model of the FPC.

[0026] Among them, the representative volume unit RVE model preferably includes 1 piezoelectric ceramic fiber, 2 polymer matrices and 3 interdigital electrodes, which includes a structural model and corresponding material properties. Among them, the material properties include parameters such as elastic modulus, Poisson's ratio, conductivity, etc. corresponding to the material used. For example, in this embodiment, the piezoelectric ceramic fiber preferably uses PZT-5H, the polymer matrix uses epoxy resin, and the interdigital electrodes use copper electrodes. According to these materials, its Young's modulus, shear modulus, Poisson's ratio, dielectric constant, piezoelectric constant and other parameters can be found.

[0027] The structural model is for example Figure 2a , Figure 2b As shown, the polymer matrix is ​​respectively located on two opposite sides of the piezoelectric ceramic along the X direction to form a piezoelectric active layer with the piezoelectric ceramic, and the interdigitated electrodes are respectively located on two opposite sides of the piezoelectric active layer along the Z direction, wherein the X direction is perpendicular to the Z direction.

[0028] Generally, at present, the structural models mainly include d31 type structural model and d33 type structural model with different polarization types; Figure 2a The d31-type structural model shown and Figure 2bThe d33 type structural model shown in the figure is used as an example to explain the parameter design and optimization process of the two in detail. Among them, the polarization type of the d31 type structural model is transverse polarization with the polarization direction perpendicular to the surface of the flexible piezoelectric composite material sheet, and the positive and negative poles of the interdigitated electrodes in the d31 type structural model are respectively located on the two opposite surfaces of the flexible piezoelectric composite material sheet; the polarization type of the d33 type structural model is longitudinal polarization with the polarization direction parallel to the surface of the flexible piezoelectric composite material sheet, and the positive and negative poles of the interdigitated electrodes in the d33 type structural model are both located on the two opposite surfaces of the flexible piezoelectric composite material sheet.

[0029] Piezoelectric ceramic fiber parameter analysis step: Based on the representative volume unit RVE model, adjust the volume fraction of the piezoelectric ceramic fiber to calculate the deformation of the RVE model under a preset voltage under different parameters, and then obtain the relationship between the volume fraction of the piezoelectric ceramic fiber and the piezoelectric constant.

[0030] In the specific implementation, the volume fraction of the piezoelectric ceramic fibers in the FPC is optimized by adjusting the ratio of the width of the piezoelectric ceramic fibers to the width of the polymer matrix under the condition that the width of the RVE model is the same, that is, the sum of the widths of the piezoelectric ceramic fibers and the polymer matrix is ​​the same, so as to adjust the volume fraction of the piezoelectric ceramic fibers in the FPC. satisfy: ; In the formula, is the width of the piezoelectric ceramic fiber, Under the same voltage condition, the deformation of the RVE model with different piezoelectric ceramic fiber volume fractions under the action of a preset voltage can be calculated to obtain the relationship between the volume fraction of the piezoelectric ceramic fiber and the piezoelectric constant, and then the relationship between the actuation displacement of the FPC and the volume fraction of the piezoelectric ceramic fiber.

[0031] According to the relationship between the volume fraction of piezoelectric ceramic fibers and the piezoelectric constant, when the volume fraction of piezoelectric ceramic fibers is increased, the model strain under the same preset voltage condition increases, thereby effectively improving the piezoelectric performance of the FPC. In addition, when the volume fraction of the piezoelectric ceramic fibers is less than the preset value, the volume fraction of the piezoelectric ceramic fibers increases slowly. When the volume fraction of the piezoelectric ceramic fibers is greater than the preset value, increasing the fiber volume fraction will make the piezoelectric performance more significantly improved, that is, the volume fraction of the piezoelectric ceramic fibers should be set to be greater than the preset value. Next, when optimizing the specific parameters of the volume fraction of the piezoelectric ceramic fibers, the volume fraction of the appropriate piezoelectric ceramic fibers can be obtained based on the actual piezoelectric performance requirements and the relationship between the volume fraction of the piezoelectric ceramic fibers and the piezoelectric constant. As an example, in this embodiment, the volume fraction of the piezoelectric ceramic fibers is preferably between 70% and 85%. More preferably, the volume fraction of the piezoelectric ceramic fibers is 75%.

[0032] Furthermore, the present invention also finds that increasing the volume fraction of piezoelectric ceramic fibers will affect the mechanical properties of the piezoelectric active layer, thereby changing the flexibility and bendability of the FPC. Therefore, in the piezoelectric ceramic fiber parameter analysis step, the relationship between the mechanical properties of the FPC and the volume fraction of the piezoelectric ceramic fibers is also considered. Specifically, under the same force load, by adjusting different piezoelectric ceramic fiber volume fractions to calculate the RVE model strain of the FPC, the relationship between the mechanical properties of the FPC and the volume fraction of the piezoelectric ceramic fibers can be obtained. According to the relationship between the mechanical properties of the FPC and the volume fraction of the piezoelectric ceramic fibers, increasing the volume fraction of the piezoelectric ceramic fibers increases the stiffness of the piezoelectric active layer, thereby increasing the stiffness of the FPC, and reducing the strain under the same force load, that is, the flexibility and bendability of the FPC are reduced.

[0033] Therefore, in the process of optimizing the volume fraction of piezoelectric ceramic fibers, the actual piezoelectric performance requirements and the flexibility and bendability requirements can be comprehensively considered, and the actual volume fraction of piezoelectric ceramic fibers can be comprehensively determined through the relationship between the mechanical properties of FPC and the volume fraction of piezoelectric ceramic fibers, and the relationship between the volume fraction of piezoelectric ceramic fibers and the piezoelectric constant.

[0034] The step of analyzing the parameters of the interdigitated electrodes is as follows: based on the representative volume unit RVE model, the width of the interdigitated electrodes and the spacing between adjacent interdigitated electrodes are adjusted respectively to calculate the electric field distribution between adjacent interdigitated electrodes under the action of the preset voltage, and then the relationship between the width of the interdigitated electrodes, the spacing between adjacent interdigitated electrodes and the polarization effect is obtained.

[0035] In specific implementation, due to the presence of interdigital electrodes inside the FPC, the electric field distribution is uneven. According to the electric field distribution, the area inside the FPC can be divided into a dead zone and a uniform polarization zone, such as Figure 4a , Figure 4b As shown, the dead zone refers to the area of ​​the piezoelectric active layer located below the interdigitated electrodes, in which the longitudinal electric field is unevenly distributed and the direction of the electric field lines varies greatly. The uniform polarization zone refers to the area of ​​the piezoelectric active layer located between the two electrodes, in which the longitudinal electric field is evenly distributed. When the FPC is polarized, the uniform polarization zone can be polarized. And when the FPC is working, the electric field in the uniform polarization zone is the main working electric field. Therefore, the proportion of the length of the uniform polarization zone between the two electrodes is an important indicator affecting the sensing / actuation performance of the FPC.

[0036] Furthermore, for the D33 type FPC in the D33 effect driving mode, its working electric field is parallel to the electric field in the fiber direction, that is, the electric field along the Y-axis direction. Therefore, the Y component of the electric field strength is an important indicator affecting the sensing / actuation performance of the D33 type FPC; for the D31 type FPC in the D31 effect driving mode, its working electric field is perpendicular to the electric field in the fiber direction, that is, the electric field along the Z-axis direction. Therefore, the Z component of the electric field strength is an important indicator affecting the sensing / actuation performance of the D31 type FPC.

[0037] In order to effectively illustrate the influence of the spacing between adjacent interdigital electrodes on the sensing / actuation performance of FPC, in the interdigital electrode parameter analysis step, by adjusting the spacing between adjacent interdigital electrodes in the RVE model of d31 type FPC and d33 type FPC, and calculating the electric field distribution inside the FPC under the same voltage, the relationship between the spacing between adjacent interdigital electrodes and the proportion of the uniform polarization area can be obtained. According to the relationship, increasing the spacing between adjacent interdigital electrodes can increase the proportion of the uniform polarization area between the two electrodes, thereby enhancing the polarization effect of the FPC and improving the performance of FPC vibration sensing / actuation. Therefore, the spacing between adjacent interdigital electrodes can be determined according to the polarization effect requirements of the actual FPC. In addition, when the overall active area length of the FPC is constant, increasing the spacing between adjacent interdigital electrodes will lead to a reduction in the number of electrodes, reducing the overall voltage and thus causing a decrease in sensing / actuation performance. The spacing between adjacent interdigital electrodes needs to match the active area length and the interdigit width. Based on the above, in this embodiment, the spacing between adjacent interdigital electrodes is preferably between 0.5 and 1 mm, such as 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc. The specific spacing between adjacent interdigital electrodes can be inferred according to the requirements of actual application scenarios.

[0038] Furthermore, the step of analyzing the parameters of the interdigital electrodes also adjusts the width of the interdigital electrodes in the RVE model of the d31 type FPC and the d33 type FPC, and calculates the electric field distribution inside the FPC under the same voltage to obtain the relationship between the width of the interdigital electrodes and the proportion of the uniform polarization zone. According to the relationship, it can be seen that increasing the width of the interdigital electrodes increases the proportion of the uniform polarization zone, enhances the polarization effect of the FPC, and improves the sensing / actuation performance of the FPC. However, when the electrode width increases to a certain value, continuing to increase the width of the interdigital electrodes will cause the proportion of the uniform polarization zone to decrease instead of increase, that is, an excessively large electrode width will affect the polarization working area between the two electrodes. Therefore, according to the actual polarization effect requirements of the FPC, the proportion of the uniform polarization zone can be determined, and then according to the relationship between the width of the interdigital electrodes and the proportion of the uniform polarization zone and the relationship between the spacing between adjacent interdigital electrodes and the proportion of the uniform polarization zone, the width of the interdigital electrodes and the spacing between adjacent interdigital electrodes can be determined.

[0039] In addition, due to the large gap between the stiffness of the interdigital electrode and the stiffness of the piezoelectric ceramic fiber and the polymer matrix in the piezoelectric active layer, when the FPC is subjected to force during operation, stress concentration will occur in the contact area between the interdigital electrode and the piezoelectric active layer, which may cause electrode debonding or ceramic fiber fracture in severe cases. Therefore, in the interdigital electrode parameter analysis step, it also includes adjusting the width of the interdigital electrode, and performing mechanical simulation under the preset stress applied to the RVE model to obtain the relationship between the width of the interdigital electrode and the maximum stress in the RVE model generated when the potential is applied; according to the relationship, increasing the width of the interdigital electrode can effectively reduce the maximum stress in the FPC, thereby reducing the risk of electrode debonding or ceramic fracture in the FPC, and improving the fatigue strength of the FPC. Therefore, when optimizing the width of the interdigital electrode, the width of the interdigital electrode can be determined based on the comprehensive requirements of the flexibility range, the piezoelectric constant requirements, the maximum stress in the RVE model, and the proportion of the uniform polarization area. As an example, in this embodiment, the width of the interdigital electrode is preferably between 0.8 and 1.5 mm. For example, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, etc.

[0040] Macro model establishment step: On a macro scale, a homogenized model of the FPC is established, and the flexibility and piezoelectric constant of the FPC are calculated according to a mixing rule to obtain the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility of the FPC and the piezoelectric constant of the FPC.

[0041] In specific implementation, by establishing a macroscopic homogenization model of FPC, the influence of the volume fraction of piezoelectric ceramic fibers of FPC on the characteristics of the piezoelectric active layer can be analyzed from a macroscopic perspective, providing a solid theoretical basis for the optimal design of component parameters.

[0042] Taking PZT-5H as an example, the piezoelectric ceramic fiber is constructed according to the material parameters of PZT-5H: ; ; In the formula, represents the stiffness matrix when the electric field is constant, Represents the dielectric constant matrix when the strain is constant (second-order tensor 3*3), Represents the stress constant coupling matrix (third-order tensor 3*6, unit C / m 2 ), is stress, For strain, is the electric field, is the electric displacement.

[0043] The piezoelectric constitutive equation of the flexible piezoelectric composite material is converted into the Voigt symbol matrix form:

[0044] According to the mixing principle, it is assumed that the strain and electric field components parallel to the bonding surface of the two phases are uniform and equal in the two phases, and the stress and electric displacement directions of the two phase materials are parallel to the normal direction of the bonding surface. , , , , , , , , The same physical quantity is uniform in the two phases of the material, while the remaining physical quantity , , , , , , , , According to the volume fraction of each component, the corresponding value is represents the volume fraction of ceramic fibers, represents the volume fraction of epoxy resin matrix.

[0045] Among them, the hybrid principle (or uniform field assumption) refers to a simplified assumption made on the distribution of physical quantities such as strain, stress, electric field and electric displacement of each phase in the flexible composite piezoelectric material when bridging the macroscopic and mesoscopic mechanical properties. The assumption of the hybrid principle makes it possible to use a simplified method to estimate the macroscopic response of flexible piezoelectric composite materials when analyzing flexible piezoelectric composite materials without considering complex microstructural details. This is very useful for engineering applications and design stages, as it effectively reduces computational complexity and allows the use of equivalent homogeneous material properties for structural analysis and design.

[0046] Therefore, based on the above assumptions, the following formula can be obtained: ; ; ; ; ; ; In the formula, is expressed as the normal stress of the piezoelectric active layer, is expressed as the shear stress of the piezoelectric active layer, is represented by the normal strain of the piezoelectric active layer, is expressed as the shear strain of the piezoelectric active layer, Expressed as the electric field strength, It is expressed as electric displacement.

[0047] Next, the values ​​of the parameters constituting the elastic stiffness matrix of the flexible piezoelectric composite material are also calculated according to the linear mixing principle, so the Young's modulus of the piezoelectric active layer is , shear modulus and Poisson's ratio The formula is as follows: ; ; ; ; In the formula, is expressed as the elastic modulus of the piezoelectric active layer, is expressed as the shear modulus of the piezoelectric active layer, Expressed as the Poisson's ratio of the piezoelectric active layer.

[0048] The above formula can be used to obtain the equivalent mechanical parameters of the homogenized flexible piezoelectric composite material according to the mechanical parameters of each component material of the flexible piezoelectric composite material, and establish the mechanical model of the macroscopic homogenized material of FPC. According to material mechanics, the detailed form of the stiffness matrix of the FPC flexible piezoelectric composite material is:

[0049] Among them, the preparation process of FPC makes it show obvious anisotropy characteristics in mechanical properties, and from the component parameter composition of the flexible piezoelectric composite material, it can be found that the material has two orthogonal symmetry planes, so the anisotropic stiffness matrix can be further simplified, and the material stiffness matrix under orthogonal anisotropy conditions is obtained as follows:

[0050] Then, according to the orthogonal anisotropy of material mechanics, the calculation formula of each parameter of the stiffness matrix can be obtained as follows: , , , , , , .

[0051] Under the first type of mechanical boundary and electrical boundary conditions, when the FPC is under constant stress or no external load is applied, the material will be deformed by the electric field, so the electromechanical coupling coefficient of the FPC is:

[0052] Among them, each coefficient represents that the external electric field along the fiber polarization direction generates stress along the perpendicular fiber polarization direction, or the material strain is applied without applying an external electric field to generate charge along the perpendicular fiber polarization direction. The principles of the other electromechanical coupling coefficients are the same. The piezoelectric coupling matrix can be obtained as follows:

[0053] Combining the above formulas, the piezoelectric constitutive equation that characterizes the flexible piezoelectric composite material can be finally obtained as follows:

[0054]

[0055] In the formula, , , It is expressed as the normal stress of the piezoelectric active layer in the x-axis, y-axis, and z-axis; , , They represent the shear stress of the piezoelectric active layer in the x-axis, y-axis, and z-axis respectively; , , They are respectively represented as the positive strain of the piezoelectric active layer in the x-axis, y-axis, and z-axis, , , are the shear strains of the piezoelectric active layer in the x-axis, y-axis, and z-axis, respectively. , , They are respectively represented as the electric field strength of the x-axis, y-axis, and z-axis, , , They are represented as the electric displacements of the x-axis, y-axis, and z-axis respectively.

[0056] It should be noted that the material properties of the above-mentioned piezoelectric active layer including the stiffness matrix, the flexibility matrix and the piezoelectric constant matrix can all be calculated from the size and component parameters of the piezoelectric ceramic fibers, the size and component parameters of the polymer matrix and the volume fraction of the piezoelectric ceramic fibers.

[0057] According to the above formula, when the volume fraction of piezoelectric ceramic fibers in the piezoelectric active layer is different, the material parameters and piezoelectric effect parameters of the piezoelectric active layer change with the volume fraction. Therefore, the flexibility and load strain of the FPC are mainly affected by the material flexibility, and the flexibility matrix is ​​regulated by parameters such as the elastic modulus, shear modulus, and Poisson's ratio of the piezoelectric active layer. The piezoelectric effect is mainly affected by the piezoelectric constant of the piezoelectric active layer. By calculating the material elastic modulus, shear modulus, Poisson's ratio, flexibility and piezoelectric constant of the piezoelectric active layer under different conditions of the volume fraction of piezoelectric ceramic fibers, the relationship between the volume fraction of piezoelectric ceramic fibers and flexibility and bendability can be obtained. That is, by comprehensively considering the performance of the piezoelectric properties and mechanical properties of the FPC under different piezoelectric ceramic fiber volume fractions, the specific parameters of the volume fraction of piezoelectric ceramic fibers can be obtained. In this embodiment, the preferred volume fraction of the piezoelectric ceramic fibers is between 70% and 85%, and the more preferred volume fraction of the piezoelectric ceramic fibers is 80%.

[0058] Parameter optimization step: According to the preset flexibility range requirements and piezoelectric constant requirements of the FPC, the volume fraction of the piezoelectric ceramic fiber, the width of the interdigital electrode and the spacing between adjacent interdigital electrodes are derived in combination with the relationship between the width of the interdigital electrode, the spacing between adjacent interdigital electrodes and the polarization effect, and the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility and piezoelectric constant of the FPC.

[0059] In specific implementation, the application environment and the controlled structural parts are first evaluated to select the appropriate flexibility range requirements and piezoelectric constant requirements, and then the parameters of the flexible piezoelectric composite material are designed in combination with the above steps.

[0060] In order to effectively illustrate the solution of the above embodiment, the d31 type FPC and d33 type FPC are analyzed by taking the piezoelectric ceramic fiber as PZT-5H, the polymer matrix as epoxy resin, and the interdigital electrode as copper electrode as an example to perform parameter optimization analysis. Among them, the representative volume unit RVE model of FPC includes 1 piezoelectric ceramic fiber, 2 epoxy resin matrices and 3 copper electrodes. The structural model of d31 type FPC is as follows: Figure 3a As shown, the structural model of d33 type FPC is as follows Figure 3b shown.

[0061] The initial geometric parameters of the FPC are set as shown in the following table:

[0062] The material parameters of each component of the RVE model are shown in the following table:

[0063] Next, based on the mesoscopic RVE model of the FPC established above, the parameters of the interdigital electrodes are adjusted, including the spacing between adjacent interdigital electrodes and the width of the interdigital electrodes. When adjusting the spacing between adjacent interdigital electrodes of the d31-type FPC and the d33-type FPC to calculate the electric field distribution inside the FPC when the same voltage acts, the proportion of the uniform polarization area between the two electrodes increases, the polarization effect of the FPC is enhanced, and the performance of the FPC vibration sensing / actuation is improved. Therefore, by obtaining the relationship between the spacing between adjacent interdigital electrodes and the proportion of the uniform polarization area, the relationship between the spacing between adjacent interdigital electrodes and the polarization effect of the FPC can be obtained.

[0064] Specifically, for the d31 type FPC, increasing the spacing between adjacent interdigital electrodes increases the proportion of the uniform polarization area, enhances the polarization effect of the FPC, and improves the vibration sensing / actuation performance of the FPC. The relationship between the spacing between adjacent interdigital electrodes and the proportion of the uniform polarization area is as follows: Figure 5aFor d33 type FPC, increasing the spacing between adjacent interdigital electrodes increases the proportion of the uniform polarization area between the two electrodes, enhances the polarization effect of the FPC, and improves the performance of the FPC vibration sensing / actuation. The relationship between the spacing between interdigital electrodes and the proportion of the uniform polarization area is shown in Figure 5b As shown; that is, by increasing the spacing between adjacent interdigital electrodes, the proportion of the uniform polarization region between the two interdigital electrodes can be effectively increased, thereby enhancing the sensing / actuation performance of the FPC.

[0065] Therefore, in the design of the spacing between adjacent interdigital electrodes of d31-type FPC and d33-type FPC, the proportion of the uniform polarization area can be adjusted accordingly according to the actual sensing / actuation performance requirements of the FPC, so as to obtain the appropriate parameters of the spacing between adjacent interdigital electrodes. In addition, since the overall active area length of the FPC is constant, increasing the spacing between adjacent interdigital electrodes will lead to a reduction in the number of electrodes, reducing the overall voltage and thus causing a decrease in sensing / actuation performance. The spacing between adjacent interdigital electrodes needs to match the active area length and the interdigital width. Therefore, the relationship between the number of electrodes and the spacing between adjacent interdigital electrodes can be further comprehensively considered to further optimize the parameters.

[0066] Furthermore, when adjusting the width of the interdigital electrodes of the d31-type FPC and the d33-type FPC to calculate the electric field distribution when the same voltage acts on the inside of the FPC, increasing the width of the interdigital electrodes can increase the proportion of the uniform polarization area, enhance the polarization effect of the FPC, and improve the sensing / actuation performance of the FPC. Therefore, by obtaining the relationship between the width of the interdigital electrodes and the proportion of the uniform polarization area, the relationship between the width of the interdigital electrodes and the polarization effect of the FPC can be obtained. Specifically, for the d31-type FPC, the relationship between the spacing between adjacent interdigital electrodes and the proportion of the uniform polarization area is as follows: Figure 6a As shown. Figure 6a It can be seen that when the width of the interdigital electrode is 0.125mm, the proportion of the uniform polarization area is the largest, and when it is lower or higher than 0.125mm, the proportion of the uniform polarization area decreases. Therefore, the electrode width can be preferably 0.125mm. Similarly, for the d33 type FPC, the relationship between the spacing between adjacent interdigital electrodes and the proportion of the uniform polarization area is as follows: Figure 6b As shown. Figure 6b It can be seen that when the width of the interdigital electrode increases to more than 0.125 mm, the proportion of the uniform polarization area decreases instead of increases with the further increase of the interdigital electrode width, which shows that an excessively large electrode width will affect the polarization working area between the two electrodes. Therefore, the preferred electrode width is 0.125 mm.

[0067] In addition, due to the large difference between the stiffness of the copper electrode and the stiffness of the piezoelectric ceramic fiber and epoxy resin matrix in the piezoelectric active layer, when the FPC is subjected to force during operation, stress concentration will occur in the contact area between the interdigitated electrode and the piezoelectric active layer, which may cause electrode debonding or ceramic fiber breakage in severe cases. Therefore, stress is applied to the RVE model of the FPC to perform mechanical simulation. The simulation calculation is independent of the electrode distribution. The FPC results of the two polarization modes are the same, and the relationship between the width of the interdigitated electrode and the maximum stress in the RVE model can be obtained as follows: Figure 7 As shown, according to Figure 7 It can be seen that increasing the width of the interdigital electrodes can effectively reduce the maximum stress in the FPC, reduce the risk of electrode debonding or ceramic fracture inside the FPC, and improve the fatigue strength of the FPC. In particular, when the width of the interdigital electrodes exceeds 0.1 mm, the maximum stress in the FPC is significantly reduced. Therefore, considering comprehensively, the preferred width of the interdigital electrodes is 0.125 mm.

[0068] Next, consider the optimal design of the volume fraction of piezoelectric ceramic fibers in FPC. Under the condition that the model width is the same, that is, the sum of the widths of the piezoelectric ceramic fibers and the epoxy resin is the same, the volume fraction of the piezoelectric ceramic fibers in FPC can be adjusted by adjusting the ratio of the widths of the piezoelectric ceramic fibers to the epoxy resin. Therefore, by adjusting different parameters of the volume fraction of the piezoelectric ceramic fibers and calculating the RVE model strain of the FPC under the same voltage conditions, the relationship between the actuating displacement of the FPC and the volume fraction of the piezoelectric ceramic fibers can be obtained. Among them, the relationship between the volume fraction of the piezoelectric ceramic fibers and the model strain under the same voltage conditions in the d31 type FPC and the d33 type FPC are as follows: Figure 8a , Figure 8b As shown. Figure 8a , Figure 8b It can be seen that when the volume fraction of the piezoelectric ceramic fiber is less than 75%, the piezoelectric performance increases slowly with the volume fraction of the piezoelectric ceramic fiber. When the volume fraction of the piezoelectric ceramic fiber is greater than 75%, the piezoelectric performance improvement caused by increasing the volume fraction of the piezoelectric ceramic fiber is more obvious. Therefore, it is preferred that the volume fraction of the piezoelectric ceramic fiber is equal to 75%.

[0069] In addition, increasing the volume fraction of piezoelectric ceramic fibers will affect the mechanical properties of the piezoelectric active layer and change the flexibility and bendability of the FPC. Therefore, the relationship between the volume fraction of piezoelectric ceramic fibers and their mechanical properties is also studied here. By adjusting the volume fraction of piezoelectric ceramic fibers and calculating the RVE model strain of the FPC under the same force load, the relationship between the mechanical properties of the FPC and the volume fraction of piezoelectric ceramic fibers can be obtained. Among them, the relationship between the volume fraction of piezoelectric ceramic fibers and the strain under the same force load in d31 type FPC and d33 type FPC is as follows: Figure 8a , Figure 8b As shown. Figure 8a , Figure 8b It can be seen that by increasing the volume fraction of piezoelectric ceramic fibers, the stiffness of the piezoelectric active layer can be increased, thereby increasing the stiffness of the FPC and reducing the strain under the same force load, that is, reducing the bendability. Therefore, considering the relationship between the volume fraction of piezoelectric ceramic fibers and the piezoelectric and mechanical properties, Figure 8a , Figure 8b It can be seen that when the volume fraction of the piezoelectric ceramic fiber of the FPC is about 75%, the piezoelectric performance and mechanical properties of the FPC both reach a high level. Here, the preferred volume fraction of the piezoelectric ceramic fiber of the FPC is 75%.

[0070] Next, a macroscopic homogenization model of FPC is established to analyze the effect of the volume fraction of piezoelectric ceramic fibers in FPC on the characteristics of the piezoelectric active layer from a macroscopic perspective. According to the aforementioned piezoelectric constitutive equation for characterizing flexible piezoelectric composite materials, it can be seen that when the volume fraction of piezoelectric ceramic fiber materials in the piezoelectric active layer is different, the material parameters and piezoelectric effect parameters of the piezoelectric active layer change with the volume fraction. Therefore, the material elastic modulus, shear modulus, Poisson's ratio, flexibility and piezoelectric constant of the piezoelectric active layer are calculated by adjusting the volume fraction of piezoelectric ceramic fibers. Fig. 9 As shown in the figure, when the volume fraction of piezoelectric ceramic fibers increases, the elastic modulus and shear modulus of the material increase with the increase of piezoelectric ceramic fiber content, the Poisson's ratio in five directions increases with the increase of piezoelectric ceramic fiber content, and the Poisson's ratio in one direction decreases with the increase of piezoelectric ceramic fiber content, but the change is small. From the flexibility matrix calculated from the elastic parameters of this material, it can be seen that when the volume fraction of piezoelectric ceramic fibers increases, the flexibility of the piezoelectric active layer decreases significantly, that is, the bendability of the FPC decreases. When the volume fraction of piezoelectric ceramic fibers increases, the piezoelectric constant of the overall piezoelectric active layer of the FPC increases numerically in both the d33-type FPC and the d31-type FPC, that is, the piezoelectric effect of the d33-type FPC in the d33 driving mode and the d31-type FPC in the d31 driving mode are enhanced, and the piezoelectric characteristics are improved.

[0071] Considering the piezoelectric and mechanical properties of d31 FPC and d33 FPC at different fiber volume fractions, when the volume fraction of piezoelectric ceramic fiber is 80%, the piezoelectric and mechanical properties of FPC are better. When the volume fraction of piezoelectric ceramic fiber is higher than 80%, the piezoelectric properties are not significantly increased, and the flexibility of FPC is significantly reduced, affecting its bendability. Therefore, the volume fraction of piezoelectric ceramic fiber is preferably between 75% and 80%.

[0072] Finally, the application environment and controlled structural parts are evaluated, the appropriate flexibility range and piezoelectric characteristic requirements are selected, the component parameters of the flexible piezoelectric composite material are designed to improve the actuation / sensing performance, and the appropriate parameters are selected to reduce the production cost while meeting the performance requirements.

[0073] In summary, the parameter optimization design method of the flexible piezoelectric composite material provided by the present invention utilizes multi-scale analysis modeling to study the influence of component parameters on the flexible piezoelectric composite material FPC from the aspects of action mechanism and performance characterization, and can realize the design and selection of component parameters of the flexible piezoelectric composite material FPC according to application requirements. It has the following advantages: First, through multi-scale modeling and analysis, it can combine the actuation mechanism and performance characterization, and comprehensively consider the influence of the fiber volume fraction on the sensor-actuator output and the flexibility of the sensor-actuator. Second, the existing methods cannot intuitively represent and modify the components and structural parameters of the flexible piezoelectric composite material, while the parameter optimization design method of the present invention can not only modify the required design parameters in real time, but also can intuitively see the relationship between the parameters and the required FPC performance through the multi-scale model simulation results.

[0074] Embodiment 2 The second embodiment of the present invention further provides a parameter optimization system for a flexible piezoelectric composite material, comprising at least: A mesoscopic model building module; at the mesoscopic scale, a representative volume unit RVE model of the FPC is established based on the initial geometric parameters of the FPC, and a structural model of the FPC is constructed, wherein the structural model at least includes piezoelectric ceramic fibers, a polymer matrix, and interdigital electrodes; A piezoelectric ceramic fiber parameter analysis module; based on the representative volume unit RVE model, adjusting the volume fraction of the piezoelectric ceramic fiber to calculate the deformation of the RVE model under a preset voltage under different parameters, thereby obtaining the relationship between the volume fraction of the piezoelectric ceramic fiber and the piezoelectric constant; An interdigital electrode parameter analysis module; based on the representative volume unit RVE model, adjusting the width of the interdigital electrode and the spacing between adjacent interdigital electrodes to calculate the electric field distribution between adjacent interdigital electrodes under the action of the preset voltage, thereby obtaining the relationship between the width of the interdigital electrode, the spacing between adjacent interdigital electrodes and the polarization effect; A macro model building module: On a macro scale, a homogenized model of the FPC is established, and the flexibility and piezoelectric constant of the FPC are calculated according to a mixing rule to obtain a relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility of the FPC and the piezoelectric constant of the FPC; Parameter optimization module: according to the preset flexibility range requirements and piezoelectric constant requirements of the FPC, the volume fraction of the piezoelectric ceramic fiber, the width of the interdigital electrode and the spacing between adjacent interdigital electrodes are derived in combination with the relationship between the width of the interdigital electrode, the spacing between adjacent interdigital electrodes and the polarization effect, and the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility and piezoelectric constant of the FPC.

[0075] The system analyzes the influence of the parameters of the flexible piezoelectric composite material on the performance through joint modeling analysis at the mesoscopic scale and the macroscopic scale and based on the mechanism level, thereby optimizing and adjusting the parameters of the flexible piezoelectric composite material from multiple scales, so as to effectively improve the performance of the flexible piezoelectric composite material and provide a reliable reference for the preparation of the flexible piezoelectric composite material. The specific manner in which each module in the above-mentioned embodiment 2 performs the operation has been described in detail in the embodiment 1 of the method, and will not be elaborated here.

[0076] Embodiment 3 An embodiment of the present invention also provides a storage medium, which is a non-volatile storage medium or a non-transient storage medium, on which a computer program is stored. When the computer program is run by a processor, the parameter optimization analysis method of the flexible piezoelectric composite material described in any of the above embodiments is executed.

[0077] In a specific implementation, the storage medium is a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory (Flash Memory), a hard disk (Hard Disk Drive, abbreviated as: HDD) or a solid-state drive (SSD), etc.; the storage medium may also include a combination of the above types of memory.

[0078] Embodiment 4 An embodiment of the present invention also provides a terminal, which includes a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor runs the computer program, it executes the parameter optimization analysis method of the flexible piezoelectric composite material described in any of the above embodiments.

[0079] In specific implementation, the number of processors may be one or more, and the processor may be a central processing unit (CPU). The processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components and other chips, or a combination of the above-mentioned chips. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0080] The memory and the processor can be communicatively connected via a bus or other means. The memory stores program instructions that can be executed by at least one processor. The program instructions are executed by at least one processor so that the processor executes the parameter optimization analysis method of the flexible piezoelectric composite material as described in any of the above embodiments.

[0081] In summary, the parameter optimization and analysis method and system of the flexible piezoelectric composite material provided by the present invention, the medium, and the terminal are designed through the mesoscopic model establishment step, the piezoelectric ceramic fiber parameter analysis step, the interdigitated electrode parameter analysis step, the macroscopic model establishment step, and the parameter optimization step. It can jointly model and analyze at the mesoscale and macroscale and analyze the influence of the parameters of the flexible piezoelectric composite material on its material properties, electric field distribution, polarization effect and other performance aspects based on the mechanism of action and performance characterization level, thereby realizing the design and optimization adjustment of the parameters of the flexible piezoelectric composite material at multiple scales, so as to effectively improve the performance of the flexible piezoelectric composite material and provide a reliable reference basis for the preparation of flexible piezoelectric composite materials.

[0082] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved in only one or several aspects, without having to solve all the technical problems listed in the prior art or background technology at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation on the claim.

[0083] Although the terms such as mesoscopic model building step, piezoelectric ceramic fiber parameter analysis step, interdigital electrode parameter analysis step, macroscopic model building step, parameter optimization step, representative volume unit RVE model, piezoelectric ceramic fiber, polymer matrix, interdigital electrode, etc. are used more frequently in this article, the possibility of using other terms is not excluded. The use of these terms is only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention; the terms "first", "second", etc. (if any) in the description and claims of the embodiments of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A parameter optimization analysis method for a flexible piezoelectric composite material, characterized in that: The following steps are involved: Mesoscopic model establishment step: at the mesoscopic scale, a representative volume unit RVE model of the FPC is established based on the initial geometric parameters of the FPC, and a structural model of the FPC is constructed, wherein the structural model at least includes piezoelectric ceramic fibers, a polymer matrix, and interdigital electrodes; A piezoelectric ceramic fiber parameter analysis step: based on the representative volume unit RVE model, adjusting the volume fraction of the piezoelectric ceramic fiber to calculate the deformation of the RVE model under a preset voltage under different parameters, thereby obtaining the relationship between the volume fraction of the piezoelectric ceramic fiber and the piezoelectric constant; The interdigital electrode parameter analysis step: based on the representative volume unit RVE model, adjusting the width of the interdigital electrode and the spacing between adjacent interdigital electrodes to calculate the electric field distribution between adjacent interdigital electrodes under the action of the preset voltage, thereby obtaining the relationship between the width of the interdigital electrode, the spacing between adjacent interdigital electrodes and the polarization effect; Macro model establishment step: On a macro scale, a homogenized model of the FPC is established, and the flexibility and piezoelectric constant of the FPC are calculated according to a mixing rule to obtain a relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility of the FPC and the piezoelectric constant of the FPC; Parameter optimization steps; According to the preset flexibility range requirements and piezoelectric constant requirements of the FPC, the volume fraction of the piezoelectric ceramic fiber, the width of the interdigital electrode and the spacing between adjacent interdigital electrodes are derived in combination with the relationship between the width of the interdigital electrode, the spacing between adjacent interdigital electrodes and the polarization effect, and the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility and piezoelectric constant of the FPC.

2. The parameter optimization analysis method of the flexible piezoelectric composite material according to claim 1, characterized in that: In the mesoscopic model establishment step, the structural model at least includes piezoelectric ceramic fibers, a polymer matrix, and interdigital electrodes; the polymer matrix is ​​respectively located on opposite sides of the piezoelectric ceramic along the X direction to form a piezoelectric active layer with the piezoelectric ceramic, and the interdigital electrodes are respectively located on opposite sides of the piezoelectric active layer along the Z direction, wherein the X direction is perpendicular to the Z direction; The structural model includes a d31-type structural model and a d33-type structural model with different polarization types; wherein the polarization type of the d31-type structural model is transverse polarization with a polarization direction perpendicular to the surface of the flexible piezoelectric composite material sheet, and the positive and negative poles of the interdigitated electrodes in the d31-type structural model are respectively located on the opposite surfaces of the flexible piezoelectric composite material sheet; the polarization type of the d33-type structural model is longitudinal polarization with a polarization direction parallel to the surface of the flexible piezoelectric composite material sheet, and the positive and negative poles of the interdigitated electrodes in the d33-type structural model are both located on the opposite surfaces of the flexible piezoelectric composite material sheet.

3. The parameter optimization analysis method of the flexible piezoelectric composite material according to claim 1, characterized in that: The volume fraction of the piezoelectric ceramic fiber satisfy: ; In the formula, is the width of the piezoelectric ceramic fiber, is the width of the polymer matrix.

4. The parameter optimization analysis method of the flexible piezoelectric composite material according to claim 1, characterized in that: The spacing between adjacent interdigital electrodes is between 0.5 and 1 mm, and the width of the interdigital electrodes is between 0.8 and 1.5 mm.

5. The parameter optimization analysis method of the flexible piezoelectric composite material according to claim 1, characterized in that: The step of analyzing the interdigital electrode parameters also includes adjusting the width of the interdigital electrode and performing mechanical simulation under a preset stress on the RVE model to obtain a relationship between the width of the interdigital electrode and the maximum stress in the RVE model; The parameter optimization step also includes determining the width of the interdigital electrode according to the flexibility range requirement, the piezoelectric constant requirement, the maximum stress in the RVE model, and the proportion of the uniform polarization region.

6. The parameter optimization analysis method of the flexible piezoelectric composite material according to claim 4, characterized in that: In the macro model establishment step, the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility of the FPC and the piezoelectric constant of the FPC is represented by a piezoelectric constitutive equation characterizing the flexible piezoelectric composite material; The piezoelectric constitutive equation is expressed as: In the formula, It is expressed as the stiffness matrix of FPC under orthotropic conditions; It is represented as a piezoelectric coupling matrix; , , It is expressed as the normal stress of the piezoelectric active layer in the x-axis, y-axis, and z-axis; , , They represent the shear stress of the piezoelectric active layer in the x-axis, y-axis, and z-axis respectively; , , They are respectively represented as the positive strain of the piezoelectric active layer in the x-axis, y-axis, and z-axis, , , are respectively represented as the shear strain of the piezoelectric active layer in the x-axis, y-axis, and z-axis, , , They are respectively represented as the electric field strength of the x-axis, y-axis, and z-axis, , , They are represented as the electric displacements of the x-axis, y-axis, and z-axis respectively.

7. The parameter optimization analysis method of the flexible piezoelectric composite material according to claim 1, characterized in that: The volume fraction of the piezoelectric ceramic fibers is between 70% and 85%.

8. A parameter optimization system for a flexible piezoelectric composite material, characterized in that: include: Mesoscopic model building module; Used to establish a representative volume unit RVE model of the FPC based on initial geometric parameters of the FPC at a mesoscopic scale, and construct a structural model of the FPC, wherein the structural model at least includes piezoelectric ceramic fibers, a polymer matrix, and interdigital electrodes; A piezoelectric ceramic fiber parameter analysis module; used to adjust the volume fraction of the piezoelectric ceramic fiber based on the representative volume unit RVE model to calculate the deformation of the RVE model under a preset voltage under different parameters, and then obtain the relationship between the volume fraction of the piezoelectric ceramic fiber and the piezoelectric constant; An interdigital electrode parameter analysis module; used to adjust the width of the interdigital electrodes and the spacing between adjacent interdigital electrodes based on the representative volume unit RVE model to calculate the electric field distribution between adjacent interdigital electrodes under the action of the preset voltage, and then obtain the relationship between the width of the interdigital electrodes, the spacing between adjacent interdigital electrodes and the polarization effect; Macro model building module; Used to establish a homogenization model of the FPC on a macro scale, calculate the flexibility and piezoelectric constant of the FPC according to a mixing rule, so as to obtain the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility of the FPC and the piezoelectric constant of the FPC; Parameter optimization module; It is used to derive the volume fraction of the piezoelectric ceramic fiber, the width of the interdigital electrode and the spacing between adjacent interdigital electrodes according to the preset flexibility range requirements and piezoelectric constant requirements of the FPC, combined with the relationship between the width of the interdigital electrode, the spacing between adjacent interdigital electrodes and the polarization effect, and the relationship between the volume fraction of the piezoelectric ceramic fiber and the flexibility and piezoelectric constant of the FPC.

9. A storage medium, characterized in that: The storage medium is a non-volatile storage medium or a non-transient storage medium, on which a computer program is stored. When the computer program is run by a processor, the parameter optimization analysis method for the flexible piezoelectric composite material according to any one of claims 1 to 7 is executed.

10. A terminal, characterized in that: It comprises a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and the processor executes the parameter optimization analysis method of the flexible piezoelectric composite material according to any one of claims 1 to 7 when running the computer program.

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