Double-frequency tooth-shaped curved surface piezoelectric composite base material and regulation and control method

Abstract

The invention discloses a double-frequency tooth-shaped curved surface piezoelectric composite base material and a regulation and control method, and belongs to the field of piezoelectric materials. The device comprises a first piezoelectric phase, a second piezoelectric phase, a rigid polymer layer, a flexible polymer phase located in the middle and flexible electrodes acting on the two piezoelectric phases respectively. The overall structure is in a rigid-flexible-rigid partition layout in the thickness direction, and alternately-arranged tooth-shaped geometry is formed in the transverse direction. The flexible polymer interlayer is located between the upper and lower rigid layers. The space between the rigid piezoelectric ceramic columns is filled with the flexible polymer and the rigid polymer in sequence, so that the flexible piezoelectric ceramic column has the curved surface forming capacity; meanwhile, the thicknesses of the piezoelectric columns of the piezoelectric composite material are subjected to gradient treatment, and the thicknesses of different columns and the layer distribution of the polymer are adjusted, so that the working bandwidth is accurately regulated and controlled. The dual-frequency tooth-shaped curved surface piezoelectric composite base material disclosed by the invention can keep stable electromechanical coupling performance under a complex curved surface, and meanwhile, the working frequency band is widened and the acoustic response is adjustable and controllable.

Description

Technical Field

[0001] This invention relates to a dual-frequency toothed curved surface piezoelectric composite substrate and its control method, belonging to the field of piezoelectric materials. Background Technology

[0002] Piezoelectric materials, as functional materials capable of converting energy between multiple physical fields such as electromechanical and acoustic fields, are widely used in key areas such as ultrasonic transducers, structural health monitoring, underwater acoustic detection, and non-destructive testing. With the rapid development of intelligent manufacturing, deep-sea exploration, and advanced medical equipment, piezoelectric devices are exhibiting technological trends towards high sensitivity, wide bandwidth, flexibility, curved surfaces, and adaptability to complex structures. However, existing piezoelectric materials and structures still have significant limitations in achieving broadband response and curved surface configurations, restricting their further application in complex curved acoustic devices and flexible intelligent equipment.

[0003] Traditional single-crystal piezoelectric ceramics (such as PZT single crystal) have excellent piezoelectric properties, but they generally suffer from high brittleness, poor machinability, and inability to be shaped into large-scale curved surfaces. At the same time, their inherent resonant frequencies are concentrated and their equivalent mechanical quality factor is high, resulting in narrow operating bandwidth and prominent resonance peaks, which makes them difficult to meet the requirements of applications that require broadband radiation or broadband response.

[0004] In recent years, piezoelectric composite materials (such as type 1-3 and type 2-2 composite structures) have achieved improvements in mechanical impedance, bandwidth, and machinability to some extent by adjusting the ratio of ceramic to polymer phases and changing the connection method. However, existing technologies mainly focus on planar structures, and the material thickness, flexibility, element interface stress, and vibration modes are all based on planar or quasi-planar assumptions. For devices that need to adapt to spherical, cylindrical, or complex curvature structures, traditional composite materials are prone to problems such as piezoelectric phase cracking, interface debonding, and polarization direction shift during bending and forming, which degrades piezoelectric performance and may even prevent stable surface forming.

[0005] Furthermore, existing broadband methods mostly employ matching layer and stacking methods. However, these methods are difficult to implement in curved structures and usually require sacrificing some electromechanical coupling efficiency or radiation intensity. At the same time, the methods for controlling the acoustic properties of curved piezoelectric composite materials generally lack a systematic approach, making it difficult to achieve tunability of piezoelectric properties, resonant modes, and frequency bands without damaging the overall material structure.

[0006] Therefore, there is an urgent need to develop a dual-frequency toothed curved surface composite substrate that can adapt to curved surface structures, has inherent wideband response capabilities, and whose performance can be regulated through structural or material parameters, so as to meet the application needs of complex curved surface acoustic transducers, flexible piezoelectric devices and new underwater acoustic sensing equipment. Summary of the Invention

[0007] To overcome the problems of high brittleness, difficulty in achieving curved surface forming, insufficient broadband characteristics, and limited performance control methods of existing piezoelectric ceramics, the present invention aims to provide a dual-frequency toothed curved surface piezoelectric composite substrate and its control method. By sequentially filling the spaces between rigid piezoelectric ceramic pillars with flexible polymers and rigid polymers, it achieves the ability to form curved surfaces. Simultaneously, by gradient processing of the piezoelectric pillar thickness in the piezoelectric composite material, adjusting the thickness of different pillars and the layer distribution of polymers, precise control of the operating bandwidth is achieved. The dual-frequency toothed curved surface piezoelectric composite substrate of the present invention can maintain stable electromechanical coupling performance under complex curved surfaces while achieving widened operating bandwidth and controllable acoustic response, making it suitable for fields such as underwater acoustic transducers, flexible acoustic devices, structural health monitoring, and biomedical imaging.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] This invention discloses a dual-frequency toothed curved piezoelectric composite substrate, which mainly consists of five parts: a first piezoelectric phase, a second piezoelectric phase, a rigid polymer layer, a flexible polymer phase located in the middle, and flexible electrodes acting on the two types of piezoelectric phases respectively. The overall structure presents a "rigid-flexible-rigid" partitioned layout along the thickness direction, and forms an alternating toothed geometry in the transverse direction, enabling the material to maintain flexibility while possessing dual-frequency control capability and a wide bandwidth operating range.

[0010] The first piezoelectric phase and the second piezoelectric phase have different heights; the first piezoelectric phase and the second piezoelectric phase are arranged alternately in a periodic manner.

[0011] The rigid polymer layer has a thickness not exceeding the thickness of the second piezoelectric phase.

[0012] The flexible polymer interlayer is located between the upper and lower rigid layers, forming a sandwich-like composite structure together with the two rigid polymer layers.

[0013] The first flexible electrode covers the upper and lower end faces of the first piezoelectric phase, and the second flexible electrode covers the upper and lower end faces of the second piezoelectric phase, with the negative electrodes of the two electrodes being the same; the positive electrodes of the first flexible electrode and the second flexible electrode are led out independently.

[0014] The thicknesses of the first and second piezoelectric phases are H1 and H2, respectively, and their thicknesses are different. Both types of piezoelectric materials are prepared using piezoelectric materials with high electromechanical coupling coefficients, including PZT ceramics, PMN-PT, or PIN-PMN-PT single crystals. The two types of materials are processed into square column arrays with a large aspect ratio (usually greater than 2) to ensure that thickness mode vibration is the dominant mode and reduce bandwidth attenuation caused by lateral coupling. Along the planar direction, the two types of square column array elements are arranged alternately in a periodic manner. Due to the difference in column height, two independent thickness mode resonances can be formed in the same composite material structure, thereby achieving dual resonance and broadband response.

[0015] The rigid polymer layer, whose thickness does not exceed the height of the second piezoelectric phase, is used to improve the overall structural rigidity, provide mechanical support under external pressure, and reduce local stress concentration during bending of curved surfaces. This rigid layer can be prepared from epoxy resin, modified epoxy resin, acrylic resin, or reinforced polyurethane, with a preferred hardness of 60D to 90D. In one embodiment, an epoxy system with a Young's modulus of approximately 2.2 GPa is used, which can operate stably for extended periods under underwater hydrostatic pressure conditions exceeding 5 MPa.

[0016] The flexible polymer interlayer is located between the upper and lower rigid layers, forming a sandwich-like composite structure together with the two rigid polymer layers. This flexible layer provides controllable bending capability of the array facets, achieving acoustic impedance matching, while simultaneously suppressing lateral mechanical coupling between array elements and enhancing the mode purity of thickness mode vibrations. The flexible polymer layer material can be selected from silicone rubber, fluorosilicone elastomer, flexible polyurethane, or TPU, with a preferred Young's modulus of 0.5–10 MPa.

[0017] The first flexible electrode covers the upper and lower end faces of the first piezoelectric phase, and the second flexible electrode covers the upper and lower end faces of the second piezoelectric phase, with both electrodes having the same negative electrode. The positive electrodes of the first and second flexible electrodes are independently led out, thereby achieving electrical decoupling during dual-frequency driving and receiving, and avoiding mutual interference between structures of different thicknesses. The flexible electrodes can be made of flexible metal foil (such as gold-plated or copper foil) or flexible conductive film. The overall thickness of the electrode layer should be less than 0.1 mm to ensure that electrode cracking or delamination does not occur during bending deformation.

[0018] This invention also discloses a parameter control method for a cascaded piezoelectric composite material, used to control the parameters of the dual-frequency toothed curved surface piezoelectric composite substrate. The heights of the first and second piezoelectric phases in the cascaded piezoelectric composite material are obtained by the following method;

[0019] The dual-frequency toothed piezoelectric composite substrate is composed of a piezoelectric phase, a rigid phase, and a flexible polymer phase. The polymer portion of the composite substrate is connected in a "rigid-flexible-rigid" configuration. In the thickness direction, each cascaded piezoelectric composite material belongs to type 1-3, and the three-layer cascaded piezoelectric composite material satisfies the type e equation, expressed as:

[0020]

[0021] Among them, T i It is the stress component, S j It is the strain component, E k It is the electric field component, D k It is the electric displacement component; These are the components of the elastic constant under a constant electric field. It is the piezoelectric stress constant. Indicates to transpose; It is the dielectric constant component under constant strain (i,j = 1,2,...,6, k = 1,2,3).

[0022] The matrix form is as follows:

[0023]

[0024] The electrodes of the toothed piezoelectric composite substrate are polarized along the thickness direction. Neglecting transverse strain, the following exists:

[0025]

[0026] Therefore, the formula Simplify to the following formula The equation is:

[0027]

[0028] According to the series and parallel laws, the strain of each layer (1-3) of the dual-frequency toothed piezoelectric composite substrate is continuous in the x and y directions, and the stress is equal to the weighted sum of the components, i.e.:

[0029]

[0030] In the z-direction, the stress of each component of the dual-frequency toothed piezoelectric composite material is continuous, and the strain is equal to the weighted sum of the components, i.e.:

[0031]

[0032] In the formula to In the formula, v1, v2, and v3 represent the volume fractions of the first, second, and third layers, respectively. The superscript 'c' represents the rigid portions (1-3), the superscript 's' represents the flexible portions (1-3), and the parameter without a superscript represents the entire toothed composite substrate. To simplify calculations, S3 and T3, and E3 and D3 are usually interchanged, as shown in the formula. As shown:

[0033]

[0034] in:

[0035]

[0036] Will , Bring into In this process, the piezoelectric equation for the entire composite substrate is obtained, namely:

[0037]

[0038] Finally, the formula Transformed into standard piezoelectric e-type equations In this process, the parameters of the dual-frequency toothed curved surface piezoelectric composite substrate are obtained.

[0039] in:

[0040] ; ; ;

[0041] ; ; ;

[0042] Furthermore, the electromechanical coupling coefficient k of the composite substrate was obtained. t The formula is as follows:

[0043]

[0044] The electromechanical properties of toothed curved surface piezoelectric composite substrates are optimized by adjusting the volume fraction of the piezoelectric phase and the polymer phase.

[0045] Using formula Based on the working frequency of the dual-frequency toothed curved surface piezoelectric composite substrate, the thickness of the piezoelectric column corresponding to the high and low frequencies is determined.

[0046]

[0047] Furthermore, by utilizing the difference in column height, two independent thickness mode resonances are formed within the same composite substrate structure, thereby achieving dual resonance and broadband response.

[0048] Beneficial effects:

[0049] 1. The present invention discloses a dual-frequency toothed curved surface piezoelectric composite substrate and its control method. By using piezoelectric composite materials in the curved surface configuration, the thickness vibration mode, radial vibration mode and curvature-related mode are synergistically involved in sound radiation, thereby breaking through the limitations of traditional curved surface ceramic transducers with single resonant modes and narrow bandwidth, achieving a wider effective frequency domain range, and meeting the needs of broadband underwater acoustic detection and communication.

[0050] 2. This invention discloses a dual-frequency toothed curved surface piezoelectric composite substrate and its control method. By combining the low acoustic impedance of the piezoelectric composite material with a continuous curved radiating surface, interface reflection loss can be effectively reduced, and the radiation efficiency of sound energy into the water medium can be improved. Under the same driving conditions, higher sound pressure levels and longer transmission distances can be obtained, significantly improving the overall performance of the device.

[0051] 3. The present invention discloses a dual-frequency toothed curved surface piezoelectric composite substrate and control method. The piezoelectric composite material contains a polymer phase inside, and its flexibility is significantly higher than that of traditional ceramic materials. It can be processed into curved surface structures with various radii of curvature while maintaining acoustic performance, thus making it suitable for complex mounting surfaces, curved carriers or AUV shells and other scenarios, enhancing application flexibility.

[0052] 4. The present invention discloses a dual-frequency toothed curved surface piezoelectric composite substrate and control method. The "ceramic-polymer" microstructure of the composite material can effectively disperse local stress, avoid the problem of cracking or performance degradation of curved ceramics, and enable the transducer to maintain stable and reliable acoustic output in the deep sea high static pressure environment, which is suitable for high static pressure underwater environment.

[0053] 5. The present invention discloses a dual-frequency toothed curved surface piezoelectric composite substrate and control method, which uses a continuous curved surface radiation surface to reduce the interference fringes present in traditional spliced ​​arrays, making the circumferential sound pressure distribution smoother and obtaining a more uniform full-circumferential sound field, which is beneficial to realizing functions such as omnidirectional detection, underwater positioning and wide coverage monitoring. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the three-dimensional structure of the dual-frequency toothed curved surface piezoelectric composite substrate proposed in this invention.

[0055] Figure 2 This is a schematic diagram of the planar structure of a dual-frequency toothed piezoelectric composite substrate.

[0056] Figure 3 The resonant frequency f of the piezoelectric composite substrate s Curve showing the variation of thickness t.

[0057] Figure 4 The simulated admittance curve of the dual-frequency toothed curved surface piezoelectric composite substrate is shown.

[0058] Figure 5 This is a process flow diagram for a dual-frequency toothed piezoelectric composite substrate.

[0059] In the figure, 1—first piezoelectric phase, 2—second piezoelectric phase, 3—flexible polymer, 4—rigid polymer, 5—first flexible electrode, and 6—second flexible electrode. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0061] Example 1: Structural Design of Dual-Frequency Toothed Curved Surface Piezoelectric Composite Substrate

[0062] like Figure 1 As shown, the dual-frequency toothed curved surface piezoelectric composite substrate disclosed in this embodiment is composed of a first piezoelectric phase 1, a second piezoelectric phase 2, a flexible polymer 3, a rigid polymer 4, and corresponding first flexible electrode 5 and second flexible electrode 6.

[0063] Figure 2 A schematic diagram of the planar structure of the dual-frequency toothed composite substrate is provided, i.e., the structure before compression bending. The first piezoelectric phase 1 and the second piezoelectric phase 2 are high aspect ratio square piezoelectric column arrays, periodically alternating in the planar direction to form a toothed structure. A flexible polymer 3 is sandwiched between rigid polymers 4, similar to a "sandwich" structure, which, while maintaining the shape, provides the piezoelectric composite substrate with a certain compressive strength.

[0064] This embodiment also discloses a method for performance control of a dual-frequency toothed curved surface piezoelectric composite substrate, which enables the same piezoelectric composite substrate to have high and low frequency resonant frequencies. By utilizing the broadband effect generated by the coupling of the two frequencies, the ability to improve the operating bandwidth is achieved. The specific control method is as follows:

[0065] If PZT-5A is chosen as the piezoelectric material, 704 silicone rubber as the flexible polymer, and 618 epoxy resin as the rigid polymer, then in the thickness direction, the piezoelectric and polymer phases of the composite substrate form a three-layer cascade structure of 1-3 PZT / epoxy, 1-3 PZT / rubber, and 1-3 PZT / epoxy, respectively. The piezoelectric composite substrate formed by these three cascaded parts satisfies the e-type equation, expressed as:

[0066]

[0067] Among them, T i It is the stress component, S j It is the strain component, E k It is the electric field component, D k It is the electric displacement component; These are the components of the elastic constant under a constant electric field. It is the piezoelectric stress constant. Indicates to transpose; It is the dielectric constant component under constant strain (i,j = 1,2,...,6, k = 1,2,3).

[0068] The matrix form is as follows:

[0069]

[0070] The electrodes of the toothed piezoelectric composite substrate are polarized along the thickness direction. Neglecting transverse strain, the following holds true:

[0071]

[0072] Therefore, the formula It can be simplified to a formula :

[0073]

[0074] According to the series and parallel laws, the strain of each layer (1-3) of the dual-frequency toothed piezoelectric composite substrate is continuous in the x and y directions, and the stress is equal to the weighted sum of the components, i.e.:

[0075]

[0076] In the z-direction, the stress of each component of the dual-frequency toothed piezoelectric composite material is continuous, and the strain is equal to the weighted sum of the components, i.e.:

[0077]

[0078] In the formula - In the formula, v1, v2, and v3 represent the volume fractions of the first, second, and third layers, respectively. The superscript 'c' represents the rigid portions (1-3), the superscript 's' represents the flexible portions (1-3), and the parameter without a superscript represents the entire toothed composite substrate. To simplify calculations, S3 and T3, and E3 and D3 are usually interchanged, as shown in the formula. As shown:

[0079]

[0080] in:

[0081]

[0082] Will , Bring into In this process, the piezoelectric equation for the entire composite substrate is obtained, namely:

[0083]

[0084] Finally, the formula Transformed into standard piezoelectric e-type equations In this process, the parameters of the dual-frequency toothed curved surface piezoelectric composite substrate are obtained.

[0085] in:

[0086] ; ; ;

[0087] ; ; ;

[0088] Furthermore, the electromechanical coupling coefficient k of the composite substrate was obtained. t The formula is as follows:

[0089]

[0090] The electromechanical properties of toothed curved surface piezoelectric composite substrates can be optimized by adjusting the volume fraction of the piezoelectric phase and the polymer phase.

[0091] Using formula Based on the working frequency of the dual-frequency toothed curved surface piezoelectric composite substrate, the thickness of the piezoelectric column corresponding to the high and low frequencies is determined.

[0092]

[0093] In this embodiment, the volume fraction v2 of the intermediate layer 1-3 type PZT / rubber structure is selected as 20% to ensure that the piezoelectric pillar has a strong thickness modulus, while reducing the lateral coupling caused by the rigid polymer. Volume fractions v1 and v3 are set to 40% respectively to ensure the high strength and mechanical stability of the toothed composite material.

[0094] Figure 3 The resonant frequency f of the piezoelectric composite substrate s The curve showing the variation with thickness t. In this embodiment, a first piezoelectric phase with thickness H1 = 4.5 mm and a second piezoelectric phase with thickness H2 = 5 mm are selected. Then, using the formula... Two resonant frequencies, f1=330KHz and f2=300KHz, can be obtained respectively.

[0095] Figure 4 Simulated admittance curves of the dual-frequency toothed piezoelectric composite substrate are presented. From the figure, we can observe a coupling peak between the two resonant frequencies f1 and f2, significantly increasing the bandwidth.

[0096] Figure 5 A fabrication process flow diagram for a dual-frequency toothed curved surface piezoelectric composite substrate is presented. After determining the cutting parameters, the toothed curved surface piezoelectric composite substrate is prepared using a "cut-fill" method, with the specific steps as follows:

[0097] Step 1: Add a substrate to the cut sample: Select 0.87mm thick 3M tape as the cutting substrate for the ceramic sample, and fix the substrate to the bottom of the 5mm thick ceramic sample to keep the ceramic sample stable during the cutting process.

[0098] Step 2: Cutting the Ceramic Skeleton: Initial cuts are made along the x and y directions using a precision cutter. In this stage, the ceramic is cut through without damaging the substrate. Based on the optimized volume fraction of the ceramic phase, parameters such as cutting step, cutting depth, and spacing are set. This step creates a two-dimensional ceramic array, preparing it for subsequent polymer filling.

[0099] Step 3: Filling with Flexible Polymer: Select a suitable flexible polymer (such as silicone rubber, polyurethane, PVDF copolymer, etc.) to infuse the cut ceramic skeleton. To ensure uniform filling, pre-treat the polymer in a vacuum defoamer, then slowly inject it into the cut slits of the ceramic, ensuring no air bubbles or voids. After the material is infused, place it in a 60℃ oven for curing for 24 hours.

[0100] Step 4: Different Thickness Cutting: After the material has cured, a precision cutting machine is used to precisely cut the sample in a periodic array. The final cut sample consists of a 5mm ceramic pillar and a 4.5mm thick ceramic pillar combined with a flexible polymer. However, the thickness of this cut is different from the first one, i.e., "different thickness". This different thickness design can be used to achieve dual-frequency resonance: the 5mm pillar height and the 4.5mm ceramic pillar correspond to different resonant frequencies.

[0101] Step 5: Remove part of the flexible polymer: Based on the intermediate layer 1-3 PZT / rubber volume fraction v2 determined in this embodiment to be 20%, a portion of the silicone rubber is removed using a precision cutting machine.

[0102] Step Six: Substrate Removal and Opposite Cutting: First, remove the attached flexible substrate. Then, perform an opposite cut on the opposite side of the sample (relative to the first side), repeating steps four and five.

[0103] Step 7: Compression Bending: Place the composite substrate sample obtained in Step 6 into a specialized mold with the desired bending curvature. Appropriately heat the substrate to reduce its stiffness, preventing cracking or damage to the ceramic skeleton during bending. Apply appropriate pressure and hold it in the mold for a certain time to allow the composite material to fully conform to the mold shape.

[0104] Step 8: Filling with Rigid Polymer: The sample, after being bent and solidified by compression molding, is infused with epoxy resin. This step aims to enhance the mechanical strength and stability of the structure and potentially adjust the impedance matching characteristics of the composite substrate. Vacuum treatment is used again to ensure minimal air bubbles during the rigid polymer infusion process. After infusion, the sample is placed in a 60°C oven for curing for 24 hours. Once cured, the polymer on the sample surface is scraped off, preparing for electrode attachment.

[0105] Step Nine: Attaching Flexible Electrodes: Conductive silver paste, flexible metal foil (such as gold-plated or copper foil), or flexible conductive film are selected as the first and second flexible electrodes. Flexible electrodes ensure that the piezoelectric composite material retains its electrical connectivity even after bending. In this embodiment, a flexible conductive film is used to cover the upper and lower surfaces of the sample.

[0106] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-frequency toothed curved surface piezoelectric composite substrate, characterized in that: It includes a first piezoelectric phase, a second piezoelectric phase, a rigid polymer layer, a flexible polymer phase located in the middle, and flexible electrodes acting on the two types of piezoelectric phases respectively; the overall structure presents a "rigid-flexible-rigid" partitioned layout along the thickness direction, and forms an alternating tooth-shaped geometry in the transverse direction, so that the material can maintain its flexibility while having dual-frequency control capability and a wide bandwidth operating range. The first piezoelectric phase and the second piezoelectric phase have different heights; the first piezoelectric phase and the second piezoelectric phase are arranged alternately in a periodic manner. The rigid polymer layer has a thickness not exceeding the thickness of the second piezoelectric phase; The flexible polymer interlayer is located between the upper and lower rigid layers, forming a sandwich-like composite structure together with the two rigid polymer layers. The first flexible electrode covers the upper and lower end faces of the first piezoelectric phase, and the second flexible electrode covers the upper and lower end faces of the second piezoelectric phase, with the negative electrodes of the two electrodes being the same; the positive electrodes of the first flexible electrode and the second flexible electrode are led out independently.

2. The dual-frequency toothed curved surface piezoelectric composite substrate as described in claim 1, characterized in that: The aspect ratio of the first and second piezoelectric phases in the square column array is greater than 2.

3. The dual-frequency toothed curved surface piezoelectric composite substrate as described in claim 1, characterized in that: The materials for the first and second piezoelectric phases are PZT ceramics, PMN-PT, or PIN-PMN-PT single crystals.

4. The dual-frequency toothed curved surface piezoelectric composite substrate as described in claim 1, characterized in that: The rigid polymer layer is made of epoxy resin, modified epoxy resin, acrylic resin or reinforced polyurethane, and has a hardness of 60 D to 90 D.

5. The dual-frequency toothed curved surface piezoelectric composite substrate as described in claim 1, characterized in that: The flexible polymer layer material is selected from silicone rubber, fluorosilicone elastomer, flexible polyurethane or TPU, with a Young's modulus of 0.5 to 10 MPa.

6. The dual-frequency toothed curved surface piezoelectric composite substrate as described in claim 1, characterized in that: Flexible electrodes can be made of flexible metal foil or flexible conductive film; the overall thickness of the electrode layer should be less than 0.1 mm.

7. A method for parameter control of a cascaded piezoelectric composite material, used to control the parameters of a dual-frequency toothed curved surface piezoelectric composite substrate as described in claims 1, 2, 3, 4, 5, or 6, characterized in that: The heights of the first piezoelectric phase and the second piezoelectric phase are obtained by the following method; In the thickness direction, each cascaded piezoelectric composite material belongs to type 1-3, and the three-layer cascaded piezoelectric composite substrate satisfies the type e equation: Among them, T i It is the stress component, S j It is the strain component, E k It is the electric field component, D k It is the electric displacement component; These are the components of the elastic constant under a constant electric field. It is the piezoelectric stress constant. Indicates to transpose; These are the dielectric constant components under constant strain (i,j = 1,2,...,6, k = 1,2,3); The matrix form of equation (1) is: The electrodes of the toothed piezoelectric composite substrate are polarized along the thickness direction, thus: Mode Simplify to formula : According to the series and parallel laws, the strain of each layer (1-3) of the dual-frequency toothed piezoelectric composite substrate is continuous in the x and y directions, and the stress is equal to the weighted sum of the components, i.e.: In the z-direction, the stress of each component of the dual-frequency toothed piezoelectric composite material is continuous, and the strain is equal to the weighted sum of the components, i.e.: In the formula to In the equation, v1, v2, and v3 represent the volume fractions of the first, second, and third layers, respectively. The superscript c represents the rigid 1-3 parts, the superscript s represents the flexible 1-3 parts, and the parameter without a superscript represents the entire toothed composite substrate. To simplify the calculation, S3 and T3, and E3 and D3 are usually interchanged, so equation (4) is transformed into equation (5). As shown: in: Will , Bring into In this process, the piezoelectric equation for the entire composite substrate is obtained, namely: The formula Transformed into standard piezoelectric e-type equation The form, that is, the parameters of the dual-frequency toothed curved surface piezoelectric composite substrate, are obtained: ; ； ; ; ; ; The electromechanical coupling coefficient k of the composite substrate was obtained. t The formula is as follows: By adjusting the volume fractions of the piezoelectric phase and the polymer phase, using the formula... Based on the operating frequency of the dual-frequency toothed curved surface piezoelectric composite substrate, the thickness of the piezoelectric pillars corresponding to the first and second piezoelectric phases is determined: 。 8. The parameter control method for a cascaded piezoelectric composite material as described in claim 7, characterized in that: By utilizing the difference in column height, two independent thickness mode resonances are formed within the same composite substrate structure, thereby achieving dual resonance and wideband response.

Images