Ultrasonic Transducer Meta Slab for Mode Conversion
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Solution Overview
Problem
Current technologies lack a method for efficient mode transformation between longitudinal and shear waves in anisotropic media, which is essential for accurate flow velocity measurement and particle concentration analysis in fluid flows within pipes.
Innovation Solution
An ultrasonic transducer employing a meta slab with an anisotropic medium, designed to achieve mode conversion resonance through specific structural and material conditions, including impedance matching and microstructure patterns, enables efficient transformation of elastic waves between longitudinal and shear waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional ultrasonic transducer is used for flow velocity measurement, then the device structure is simple, but the mode transformation efficiency between longitudinal waves and shear waves is low
Solution Approach 1:
The patent employs a meta slab composed of anisotropic composite materials with specific elastic property ratios (C11/C66 between 0.5-2.0) to achieve efficient mode transformation. The composite structure includes multiple layers with different material properties that work together to convert longitudinal waves to shear waves with high efficiency, resolving the contradiction between structural simplicity and transformation efficiency.
Solution Approach 2:
The patent optimizes specific parameters of the meta slab including thickness (d/4 where d is wavelength), elastic modulus ratios (C11/C66), and density relationships to achieve resonance conditions. By carefully controlling these parameters, the system achieves high mode transformation efficiency without requiring complex device structures, as the optimization occurs at the material and geometric parameter level rather than through structural complexity.
2Loss of energy
If the meta slab thickness is optimized for mode conversion resonance, then the mode transformation efficiency is high, but the device design complexity increases
Solution Approach 1:
The patent establishes specific parameter relationships for the meta slab: thickness equals d/4 (where d is the wavelength), elastic modulus ratio C11/C66 between 0.5-2.0, and density relationships between layers. These parameter specifications provide clear design guidelines that simplify the implementation process while achieving high transformation efficiency, preventing design complexity from becoming unmanageable.
Solution Approach 2:
The patent utilizes resonance phenomena where the meta slab thickness is set to d/4 to achieve constructive interference and maximum energy transfer during mode conversion. This resonance-based approach allows high transformation efficiency to be achieved through a simple thickness specification rather than through complex multi-layer structures or iterative design processes.
3Loss of energy
If impedance matching is achieved in the meta slab, then the energy transmission is maximized, but the material selection and design constraints increase
Solution Approach 1:
The patent defines specific impedance matching conditions: Z1 = Z2 where Z represents acoustic impedance, and establishes relationships between density (ρ) and elastic moduli (C11, C66) of the meta slab materials. These parameter specifications provide clear selection criteria that guide material choice while ensuring maximum energy transmission, balancing the need for optimized performance with manufacturing feasibility.
Solution Approach 2:
The patent employs composite material structures where layers with different impedance characteristics are combined in specific configurations. The anisotropic composite structure allows impedance matching to be achieved through material composition and arrangement rather than requiring exotic or difficult-to-obtain materials, maintaining ease of manufacture while maximizing energy transmission.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for high-efficiency flow velocity measurement and particle concentration analysis by minimizing energy loss and achieving nearly complete mode conversion, thereby enhancing the sensitivity and accuracy of fluid flow monitoring within pipes.
Implementation Method 1
a piezoelectric body configured to generate elastic waves
Implementation Method 2
a meta slab connected to the piezoelectric body and configured to induce elastic wave mode conversion resonance
Implementation Method 3
there are both longitudinal waves and shear waves because of solid atoms coupling within a medium. When these elastic waves transmit any anisotropic layer or are reflected by the anisotropic layer, a wave motion of the elastic waves may be easily transformed from longitudinal waves to shear waves or vice versa due to a mode coupling with an elastic wave mode existing in an anisotropic medium
Implementation Method 4
a wedge connected to the meta slab, attached to an external surface of a pipe, and configured to transmit elastic waves having passed through the meta slab to the pipe at a first incidence angle
Data Source
AI summary
An ultrasonic transducer employing a meta slab includes a piezoelectric body configured to generate elastic waves; a meta slab connected to the piezoelectric body and configured to induce elastic wave mode conversion resonance with respect to the elastic waves incident on the meta slab; and a wedge connected to the meta slab, attached to an external surface of a pipe, and configured to transmit the elastic waves having passed through the meta slab to the pipe. The meta slab includes an anisotropic medium and a thickness of the meta slab satisfies the equation as follows: d=m·nFS·λFS/4, d=m·nSS·λSS/4, nSS/2−nFS/2=odd. Thus, highly-efficient flow velocity measurement is possible.