Acoustic Window Composite Tuning Layer Insertion Loss
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Solution Overview
Problem
Conventional acoustic windows, such as sonar domes, experience significant insertion loss at higher frequencies due to their structural design, which limits their effectiveness in transmitting and receiving acoustic signals across a wide range of frequencies.
Innovation Solution
The acoustic window design incorporates a structural core with a composite ply and non-structural tuning layers, where the structural core's thickness is a multiple of half a sound wave's wavelength and the tuning layers' thickness is an odd multiple of a quarter wavelength, optimizing acoustic impedance and insertion loss within a desired frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional acoustic windows use a single layer or simple sandwich structure, then structural integrity is maintained, but insertion loss increases significantly at higher frequencies
Solution Approach 1:
The acoustic window is divided into three distinct layers: an outer skin, a structural core, and an inner skin. Each layer serves specific acoustic and structural functions, allowing optimization of sound transmission at different frequencies while maintaining overall structural integrity.
Solution Approach 2:
The patent employs composite material structures where the outer and inner skins may differ from the core material. This composite approach enables tailored acoustic impedance matching and resonance control to reduce insertion loss at higher frequencies while preserving structural strength.
2Strength
If the structural core thickness is increased to maintain structural integrity, then strength is improved, but acoustic impedance mismatch increases causing higher insertion loss
Solution Approach 1:
Different layers of the acoustic window are assigned different material properties and thicknesses optimized for their specific functions. The outer and inner skins are designed with properties optimized for acoustic coupling, while the core provides structural strength, creating local quality variations that resolve the contradiction between strength and acoustic performance.
Solution Approach 2:
The structural core acts as an intermediary layer between the outer and inner skins, mediating the acoustic impedance transition. By carefully selecting core thickness and material properties, it facilitates smooth acoustic energy transmission while maintaining the structural integrity needed to support the overall window assembly.
3Loss of energy
If conventional acoustic windows operate at lower frequencies, then insertion loss is reduced, but bandwidth and signal resolution are limited
Solution Approach 1:
The acoustic window design incorporates tunable parameters such as layer thicknesses and material properties that can be adjusted to optimize performance across different frequency ranges. This dynamic design approach allows the same structural configuration to effectively operate across a broader bandwidth by tuning the resonance characteristics of each layer.
Solution Approach 2:
The patent systematically varies key parameters including the thickness of each layer, acoustic impedance of materials, and density ratios to optimize performance across multiple frequencies. By changing these parameters, the acoustic window achieves reduced insertion loss while expanding the operational bandwidth and improving signal resolution capabilities.
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 configuration reduces insertion loss across a broader frequency range, enhancing the acoustic window's ability to transmit sound waves with lower attenuation, thereby improving signal resolution and bandwidth.
Implementation Method 1
An acoustic impedance of the structural core is greater than an acoustic impedance of the non-structural tuning layer. The acoustic impedance of the non-structural tuning layer is greater than the acoustic impedance of water.
Implementation Method 2
A thickness of the structural core is equal to a multiple of one-half wavelength of a sound wave within the structural core for a particular frequency, and a thickness of the non-structural tuning layers is equal to an odd multiple of one-quarter wavelength of a sound wave within the tuning layer for the particular frequency.
Data Source
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AI summary
Systems and methods for acoustic windows (100) are disclosed. An acoustic window (100) may include a structural core (110) and a non-structural tuning layer (120). The structural core (110) may include a carbon reinforced composite, and the non-structural tuning layer (120) may include an epoxy. The structural core (110) may have local minima for insertion loss. The epoxy may increase a bandwidth about the minima of frequencies which are subject to relatively low insertion loss.