Elastic Wave Metamaterial Filter for Wide-Angle Mode Conversion
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Solution Overview
Problem
Existing filters for mode conversion of elastic waves are limited to a single angle of incidence, restricting high-energy efficiency over a wide range of angles.
Innovation Solution
A full transmission device utilizing an incidence medium, transmission medium, and a filter formed with an elastic metamaterial that includes microstructures arranged in a continuous array, satisfying a wide-angle mode-converting transmission condition to convert elastic waves without reflection over a wide range of angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a filter is designed for mode conversion of elastic waves at a specific angle of incidence, then high energy efficiency is achieved at that angle, but the filter cannot realize mode conversion over a wide range of angles
Solution Approach 1:
The patent applies local quality by creating anisotropic regions with specific elastic properties within the filter structure. These localized anisotropic zones are designed to interact with elastic waves at different incidence angles, enabling mode conversion across a wide angular range while maintaining high energy efficiency through optimized local material properties and geometric configurations
Solution Approach 2:
The filter employs composite material structures combining different elastic materials with contrasting properties. This composite approach enables the filter to achieve both wide-angle adaptability and high energy efficiency by leveraging the complementary characteristics of constituent materials to control wave propagation and mode conversion across varying incidence angles
2Loss of energy
If existing filters are used for mode conversion, then mode conversion is achieved at a specific angle, but reflected waves are generated and energy efficiency is limited
Solution Approach 1:
The patent converts the harmful reflected waves into beneficial transmitted waves by designing the filter structure to induce mode conversion. The anisotropic filter transforms incident longitudinal waves into transverse waves (and vice versa) such that the waves are transmitted through the filter rather than reflected, thereby eliminating the harmful reflection while maintaining high energy efficiency across wide angle ranges
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
Realizes free mode conversion between longitudinal and transverse waves with high energy efficiency (close to 100%) over a wide range of angles (0° to 70°) without reflected waves, overcoming the limitations of existing filters.
Implementation Method 1
a longitudinal wave entering an anisotropic layer with properties satisfying special conditions may be modally converted into a transverse wave or a transverse wave into a longitudinal wave
Implementation Method 2
a frequency at which half the wavelength of an incident wave is equal to the thickness of the layer is referred to as a Fabry-Perot resonance frequency, and a wave entering with such a Fabry-Perot resonance frequency completely (100%) passes through the layer
Implementation Method 3
This phenomenon is referred to as transmodal Fabry-Perot resonance (TFPR)
Implementation Method 4
a longitudinal wave entering an anisotropic layer with properties satisfying special conditions may be modally converted into a transverse wave
Data Source
AI summary
An exemplary embodiment attempts to provide a full transmission device for wide-angle mode conversion of elastic waves which can realize mode conversion of elastic waves with high energy efficiency over a wide range of angle of incidence by a single filter. A full transmission device for wide-angle mode conversion of elastic waves includes an incidence medium where elastic waves including longitudinal waves and transverse waves enter obliquely within a preset wide angle range, a transmission medium that transmits elastic waves when the elastic waves enter the transmission medium within the wide angle range through the incidence medium, and a filter that is formed so as to satisfy a wide-angle mode conversion full-transmission condition when the filter is interposed between the incidence medium and the transmission medium, such that elastic waves entering the incidence medium within the wide angle range are completely converted without being reflected so as to be transmitted to the transmission medium.