Focused ultrasonic transducer matching layer optimization method

Abstract

The invention relates to a focused ultrasonic transducer matching layer optimization method, which comprises the following steps: S1, matching layer material component optimization: selecting components forming a matching layer material, establishing a composite material model, extracting parameters of the composite material model, and determining the maximum sound pressure of a target focusing point by combining an acoustic simulation model of a transducer; the material doping proportion required by the maximum sound pressure of the target focusing point is obtained, and the parameters of the composite material model comprise density, Young modulus and Poisson's ratio. According to the method, the material components and the structural shape of the matching layer are optimized, and the energy intensity of the focused ultrasonic transducer at the target focusing point position is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic transducers, and in particular to a method for optimizing a matching layer of a focused ultrasonic transducer. Background Art

[0002] Ultrasonic transducer is a device that can convert electrical signals into ultrasonic signals. After receiving the electrical signal, the ultrasonic transducer converts the electrical signal into ultrasonic signal according to the piezoelectric effect and transmits it. When the ultrasonic signal is reflected back during the propagation process, the ultrasonic transducer converts the ultrasonic signal into electrical signal according to the piezoelectric effect. Ultrasonic transducers are widely used in industrial flaw detection, medical ultrasound and other fields.

[0003] In ultrasonic transducers, matching layers are important components that play a vital role in the process of sound wave transmission and energy conversion. Generally speaking, the piezoelectric ceramics of ultrasonic transducers have high acoustic impedance, while the actual propagation media of ultrasonic transducers, such as air, water, human or animal tissues, generally have low acoustic impedance. If there is no matching layer, when sound waves are generated from piezoelectric ceramics and propagate into water, air or other media with smaller impedance values, a large reflection will occur at the interface where the ultrasonic transducer and the medium are in contact, causing most of the sound energy to be reflected back to the ultrasonic transducer and unable to be effectively propagated into the medium. Adding a matching layer between the transducer and the medium can effectively improve the energy transmission efficiency and increase the bandwidth, making the ultrasonic transducer work more stably within a certain frequency range.

[0004] However, the traditional matching layer uses a fixed acoustic impedance, and the intensity of the focal sound beam is determined by the structure of the curved transducer. For power focusing transducers, epoxy resin, polymer materials, etc. are generally used to directly potting the curved surface as a whole, which will cause reflection and scattering of ultrasound during propagation, which is not conducive to maximizing the energy propagation to the required medium. At the same time, during the manufacturing process, the material selection and impedance adjustment of the matching layer greatly affect the energy intensity of the ultrasonic transducer at the focal point. Summary of the invention

[0005] Based on this, it is necessary to provide a method for optimizing the matching layer of a focused ultrasonic transducer in response to the above-mentioned technical problems existing in the prior art, optimize the material composition and structural shape of the matching layer, and use it to improve the energy intensity of the focused ultrasonic transducer at the target focusing point.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for optimizing a matching layer of a focused ultrasonic transducer comprises the following steps:

[0008] S1. Optimization of matching layer material components: Select the components that constitute the matching layer material, establish a composite material model, extract the parameters of the composite material model, combine the transducer acoustic simulation model, determine the maximum sound pressure at the target focusing point, and obtain the material doping ratio required for the maximum sound pressure at the target focusing point. The parameters of the composite material model include density, Young's modulus, and Poisson's ratio.

[0009] In a feasible implementation, the matching layer material is based on RTV silicone rubber and is doped with aluminum oxide in different proportions.

[0010] In a feasible implementation, the composite material model is a composite material model based on spherical powder with uniform particle sizes randomly dispersed in an elastic matrix.

[0011] In a feasible implementation, the specific operation of extracting the parameters of the composite material model is: fixing the density of RTV silicone rubber and alumina and the mass of RTV silicone rubber in the composite material model, simulating the change of the volume ratio of RTV silicone rubber and alumina dispersion, and extracting the density, Young's modulus, and Poisson's ratio of the composite material after simulated mixing.

[0012] In a feasible implementation, in step S1, the volume ratio of RTV silicone rubber and aluminum oxide dispersion is listed as a parameterized option to obtain the doping ratio required for the maximum sound pressure at the target focusing point, thereby optimizing the matching layer material composition.

[0013] In a feasible implementation, the method also includes step S2, matching layer structure shape optimization: after the matching layer structure is confirmed, the structure is parameterized, the deformation boundary is determined, the deformation boundary is decomposed by a polynomial function, the acceptable maximum deformation displacement limit is set, the maximum sound pressure at the target focusing point is simulated and optimized, and the optimized matching layer structure shape is obtained.

[0014] In a feasible implementation, the matching layer structure is a curved matching layer structure.

[0015] In a feasible implementation, the polynomial function in step S2 includes a Bernstein polynomial function or a Lagrange polynomial function.

[0016] In a feasible implementation, the deformation boundary is defined as the contact surface between the matching layer structure and the water area.

[0017] In a feasible implementation, step S2 is performed after step S1.

[0018] Due to the adoption of the above technical solution, the present invention has the following advantages compared with the prior art:

[0019] 1. The matching layer optimization method of the present invention can reduce the repetitive process of material selection experiments and the dependence on the precise ratio of materials in the acoustic matching process. At the same time, based on the maximum sound pressure of the target focus point of the simulation optimization, the doping ratio of the corresponding RTV silicone rubber and alumina powder can be quickly obtained according to the target situation, and the ideal value of material matching can be preliminarily determined;

[0020] 2. The matching layer optimization method of the present invention can quickly achieve structural optimization of the maximum sound pressure at the target focusing point under the support of structural optimization;

[0021] 3. The matching layer optimization method of the present invention can quickly realize the optimal structural shape and material composition ratio of the matching layer under optimization objectives such as maximum sound pressure simulation at the target focal point;

[0022] 4. The matching layer optimization method of the present invention can quickly designate the corresponding ultrasonic transducer matching layer based on the preset focusing point focusing strength and the preset regional focusing strength, and quickly complete the optimization of the focused ultrasonic transducer matching layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a flow chart of the ultrasonic transducer matching layer optimization method of the present invention;

[0024] Figure 2 This is a diagram of the optimized simulation structure of the ultrasonic transducer matching layer of the present invention;

[0025] Figure 3 It is a schematic diagram of the structure of the ultrasonic transducer matching layer before optimization of the present invention;

[0026] Figure 4 It is a schematic diagram of the structure of the ultrasonic transducer matching layer after optimization of the present invention;

[0027] Figure 5 This is a comparison result diagram of the target focus points after iterative optimization of the present invention.

[0028] Among them: 101, curved piezoelectric ceramic; 102, matching layer; 103, back air cavity; 104, focusing probe propagation water area; 105, target focusing point; 106, wireless absorption water area; 201, ultrasonic transducer matching layer before optimization curve; 301, ultrasonic transducer matching layer after optimization curve. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0031] At present, for power focusing transducers, epoxy resin, polymer materials, etc. are generally directly encapsulated into a curved surface as a whole, which will cause reflection and scattering of ultrasound during propagation, which is not conducive to maximizing the energy propagation to the required medium. At the same time, during the manufacturing process, the material selection and impedance adjustment of the matching layer greatly affect the energy intensity of the ultrasonic transducer at the focus point.

[0032] On this basis, the present invention provides a method for optimizing a matching layer of a focused ultrasonic transducer, comprising the following steps:

[0033] S1. Optimization of matching layer material components: Select the components that constitute the matching layer material, establish a composite material model, extract the parameters of the composite material model, combine the transducer acoustic simulation model, determine the maximum sound pressure at the target focusing point, and obtain the material doping ratio required for the maximum sound pressure at the target focusing point. The parameters of the composite material model include density, Young's modulus, and Poisson's ratio.

[0034] The invention discloses a method for optimizing a matching layer of a focused ultrasonic transducer, which optimizes the material composition and structural shape of the matching layer to improve the energy intensity of the focused ultrasonic transducer at a target focusing point.

[0035] The present invention is described in detail below with reference to specific embodiments.

[0036] As attached Figure 1 As shown, this embodiment provides a method for optimizing a matching layer of a focused ultrasonic transducer, comprising the following steps:

[0037] S1. Optimization of matching layer material components;

[0038] S2. Matching layer structure shape optimization.

[0039] In this embodiment, step S1, matching layer material component optimization, specifically includes: selecting components constituting the matching layer material, establishing a composite material model, extracting parameters of the composite material model, combining the transducer acoustic simulation model, determining the maximum sound pressure at the target focusing point, and obtaining the material doping ratio required for the maximum sound pressure at the target focusing point, wherein the parameters of the composite material model include density, Young's modulus, and Poisson's ratio.

[0040] Doping alumina in RTV silicone rubber can change the acoustic properties of its composite material. In this embodiment, the components of the matching layer material are based on RTV silicone rubber, doped with different proportions of alumina to improve the material properties, including density, Young's modulus, Poisson's ratio, etc., and the matching layer material components are optimized on this basis. For this composite material, based on the density, Young's modulus and Poisson's ratio of the composite material, the composite material model is a composite material model based on spherical powder of uniform size particles randomly dispersed in an elastic matrix. A 0-3 type composite material model is established to simulate that the doped alumina is an isotropic elastomer after curing in RTV silicone rubber.

[0041] In this embodiment, the specific operation of extracting the parameters of the composite material model is: fixing the density of RTV silicone rubber and alumina and the mass of RTV silicone rubber in the composite material model, simulating the change of the volume ratio of RTV silicone rubber and alumina dispersion, and extracting the density ρ, Young's modulus, and Poisson's ratio of the composite material after simulated mixing.

[0042] Based on the above parameters and combined with the transducer acoustic simulation, the optimization target is determined, that is, the simulation of the maximum sound pressure at the target focusing point. Based on this target, the volume ratio of RTV silicone rubber and alumina dispersion is listed as a parameterized option. The material doping ratio required for the maximum sound pressure at the target focusing point can be obtained, so as to achieve the optimization of the matching layer material composition.

[0043] Through step S1, the density, Young's modulus and Poisson's ratio of the composite material are extracted, and a simulation of the maximum sound pressure value of the target focusing point with RTV silicone rubber doped with different proportions of aluminum oxide is constructed, which can improve the acoustic impedance matching degree of the composite material as a matching layer between piezoelectric ceramics and water.

[0044] In this embodiment, step S2 is performed after step S1, that is, after the matching layer material composition is optimized, a suitable proportion of materials is selected based on the optimized material composition to optimize the matching layer structure shape.

[0045] In this embodiment, step S2, matching layer structure shape optimization, is specifically as follows: after the matching layer structure is confirmed, the structure is parameterized, the deformation boundary is determined, the deformation boundary is decomposed by a polynomial function, the acceptable maximum deformation displacement limit is set, the maximum sound pressure at the target focusing point is simulated and optimized, and the optimized matching layer structure shape is obtained.

[0046] In this embodiment, the matching layer structure is a curved surface matching layer structure.

[0047] In the structural parameterization, the matching layer structure is parameterized and divided into fixed boundaries and deformation boundaries. The contact surface between the back of the piezoelectric ceramic and the air, the infinite area of ​​water except for the contact with the matching layer, and the lateral structure of the matching layer are defined as fixed boundaries, and the contact surface between the matching layer and the water is defined as the deformation boundary. The water space wrapped by the matching layer and the fixed boundary is the free space. Based on the above parameterized structure, the deformation boundary is determined, the deformation boundary is decomposed by a polynomial function, and the maximum displacement limit of the deformation boundary decomposed by the polynomial function is set to limit the change range. The optimization target, that is, the maximum sound pressure simulation of the target focusing point, is structurally optimized to establish the optimized maximum sound pressure under the limited displacement condition.

[0048] In this embodiment, the polynomial function includes a Bernstein polynomial function or a Lagrange polynomial function.

[0049] In a specific embodiment, based on the curved single piezoelectric ceramic single-point focused ultrasonic transducer, the fixed thickness hemispherical curved matching layer is optimized based on RTV silicone rubber doped with alumina. The thickness of the curved piezoelectric ceramic matching layer is 2.5 mm.

[0050] As attached Figures 2 to 5 As shown, the focused ultrasonic transducer includes a curved piezoelectric ceramic 101, a matching layer 102, and a back air cavity 103. The back air cavity 103 and the matching layer 102 are arranged on opposite sides of the curved piezoelectric ceramic 101.

[0051] The curved piezoelectric ceramic 101 generates a fixed frequency after receiving an electrical signal, and the vibration frequency of this embodiment is 0.68MHz. The back air cavity 103 acts as an air backing to absorb the back sound energy, and the sound wave enters the focusing probe propagation water area 104 through the matching layer 102, and finally achieves the maximum focusing intensity at the target focusing point 105. In the overall propagation process, since the impedance value of the curved piezoelectric ceramic 101 is 35, and the impedance value of water is 1, the impedance values ​​between the two are quite different, and the matching of the matching layer 102 is required to achieve the best effect.

[0052] This embodiment uses RTV silicone rubber doped with alumina to achieve component optimization of the matching layer material. The impedance value of the component RTV silicone rubber is relatively small, and adding alumina in different proportions can effectively improve the impedance value of the composite material.

[0053] All materials have inherent acoustic impedance, which indicates the difficulty of sound propagation, Z = ρc, and for wave speed, Among them, E is Young's modulus, σ is Poisson's ratio, and ρ is the material density.

[0054] This embodiment is based on RTV silicone rubber, and alumina is doped in different proportions to establish a composite material model. The composite material model is a composite material model based on spherical powder of uniform size particles randomly dispersed in an elastic matrix. A 0-3 type composite material model is established to simulate that the doped alumina is an isotropic elastomer after curing in RTV silicone rubber. Through the silicone rubber RTV initialization parameters, the density of RTV silicone rubber and alumina and the mass of RTV silicone rubber are fixed in the composite material model, and the volume ratio of RTV silicone rubber and alumina dispersion is simulated to change, and the density ρ, Young's modulus, and Poisson's ratio of the composite material after simulation mixing are extracted. Through the parametric scanning optimization of the density, Young's modulus, and Poisson's ratio of the conforming material, combined with the acoustic simulation of the transducer, the optimization target, that is, the simulation of the maximum sound pressure at the target focusing point, is determined. With this as the target, the density, Young's modulus, and Poisson's ratio are adjusted. The volume ratio of RTV silicone rubber and alumina dispersion is listed as a parameterized option, and finally the material doping ratio required for the maximum sound pressure at the target focusing point is obtained, so as to achieve the optimization of the matching layer material component.

[0055] In this example, when the volume fraction of aluminum oxide doped in the RTV silicone rubber is 6.8%, the target focusing point 105 obtains the material optimization target value sound pressure.

[0056] Based on the current doping ratio of RTV silicone rubber and alumina, the shape of the matching layer structure is optimized.

[0057] As attached Figure 3 As shown, based on the curve 201 before optimization of the ultrasonic transducer matching layer, the structure is parameterized, the deformation boundary is determined, the deformation boundary is decomposed by a polynomial function, the acceptable maximum deformation displacement limit is set, the maximum sound pressure at the target focusing point is simulated and optimized, and the optimized matching layer structure shape is obtained.

[0058] In the structural parameterization, the matching layer structure is parameterized and distinguished into fixed boundaries and deformation boundaries. The contact surface between the curved piezoelectric ceramic 101 and the back air cavity 103, the infinite water area except for the contact with the matching layer 102, and the lateral structure of the matching layer 102 are defined as fixed boundaries, and the contact surface between the matching layer 102 and the focusing probe propagation water area 104 is defined as a deformation boundary. The water area space wrapped by the matching layer 102 and the fixed boundary is a free space. Based on the above parameterized structure, the deformation boundary is determined, and the deformation boundary is decomposed by the Lagrangian polynomial function. The maximum displacement limit of the deformation boundary decomposed according to the polynomial function is set to limit the change range. The optimization target, that is, the maximum sound pressure simulation of the target focusing point, is iteratively optimized to establish the optimized maximum sound pressure under the limited displacement condition and the corresponding matching layer structure. The optimized curve 301 of the ultrasonic transducer matching layer is shown in the attached figure. Figure 4 shown.

[0059] Will attach Figure 3 With attached Figure 4 The matching layer curves shown in the figure are compared with the results shown in the attached figure. Figure 5 As shown in the figure, the final absolute total sound pressure intensity of the optimized curve is 2.2 times that of the curve before optimization, taking the value before optimization as 1, thus achieving the optimization goal of the ultrasonic focusing sound pressure value at the target focusing point.

[0060] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for optimizing a matching layer of a focused ultrasonic transducer, characterized in that: The steps include: S1. Optimization of matching layer material components: Select components constituting the matching layer material, establish a composite material model, extract parameters of the composite material model, combine the transducer acoustic simulation model, determine the maximum sound pressure at the target focusing point, and obtain the material doping ratio required for the maximum sound pressure at the target focusing point, wherein the parameters of the composite material model include density, Young's modulus, and Poisson's ratio.

2. The method for optimizing the matching layer of a focused ultrasonic transducer according to claim 1, characterized in that: The matching layer material is based on RTV silicone rubber and is doped with aluminum oxide in different proportions.

3. The method for optimizing the matching layer of a focused ultrasonic transducer according to claim 2, characterized in that: The composite material model is a composite material model based on spherical powder with uniform particle size and randomly dispersed in an elastic matrix.

4. The method for optimizing the matching layer of a focused ultrasonic transducer according to claim 3, characterized in that: The specific operation of extracting the parameters of the composite material model is: fixing the density of RTV silicone rubber and alumina and the mass of RTV silicone rubber in the composite material model, simulating the change of the volume ratio of RTV silicone rubber and alumina dispersion, and extracting the density, Young's modulus and Poisson's ratio of the composite material after simulation mixing.

5. The method for optimizing the matching layer of a focused ultrasonic transducer according to claim 4, characterized in that: In the step S1, the volume ratio of RTV silicone rubber and alumina dispersion is listed as a parameterized option to obtain the doping ratio required for the maximum sound pressure at the target focusing point, thereby optimizing the matching layer material composition.

6. The method for optimizing the matching layer of a focused ultrasonic transducer according to claim 1, characterized in that: The method further includes step S2, optimizing the matching layer structure shape: after the matching layer structure is confirmed, the structure is parameterized, the deformation boundary is determined, the deformation boundary is decomposed by a polynomial function, the acceptable maximum deformation displacement limit is set, the maximum sound pressure at the target focusing point is simulated and optimized, and the optimized matching layer structure shape is obtained.

7. The method for optimizing the matching layer of a focused ultrasonic transducer according to claim 6, characterized in that: The matching layer structure is a curved surface matching layer structure.

8. The method for optimizing the matching layer of a focused ultrasonic transducer according to claim 6, characterized in that: The polynomial function in step S2 includes a Bernstein polynomial function or a Lagrange polynomial function.

9. The method for optimizing the matching layer of a focused ultrasonic transducer according to claim 6, characterized in that: The deformation boundary is defined as the contact surface between the matching layer structure and the water area.

10. The method for optimizing the matching layer of a focused ultrasonic transducer according to claim 6, characterized in that: The step S2 is performed after the step S1.

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