Acoustic Window With Cellular Core For Sonar Hulls
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Solution Overview
Problem
Existing acoustic window designs face challenges in balancing structural and acoustic requirements, particularly at high frequencies, where meeting structural needs while maintaining acceptable acoustic performance is difficult.
Innovation Solution
The acoustic window design incorporates a pair of structural septa with a core layer featuring cellular reinforcement and a transmission medium, encapsulated by an elastomeric filler, which is laminated between the septa to enhance both structural integrity and acoustic transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single rigid sheet of high-strength material is used for the acoustic window, then structural strength to withstand hydrodynamic forces is improved, but acoustic noise generation and signal reflection increase
Solution Approach 1:
The acoustic window employs a composite structure consisting of multiple layers including rigid septa for structural strength and a core layer made of elastomeric material with acoustic damping properties. This composite construction allows the window to simultaneously withstand hydrodynamic forces while reducing acoustic noise generation and signal reflection through the damping characteristics of the elastomeric core layer.
Solution Approach 2:
The invention changes the physical parameters of the acoustic window by introducing a multi-layer construction with varying material properties. The rigid septa provide structural integrity while the elastomeric core layer provides acoustic damping, creating a system where different layers serve different functional requirements and collectively resolve the contradiction between strength and acoustic performance.
2Reliability
If the core and septa layers are made thin to meet acoustic requirements in medium frequency applications, then acoustic transparency is improved, but structural integrity deteriorates
Solution Approach 1:
The composite structure allows thin septa to maintain acoustic transparency while the elastomeric core layer provides the necessary structural support. The combination of rigid but thin septa with the compliant core creates a sandwich structure that achieves both acoustic performance and structural integrity without requiring thick individual layers.
Solution Approach 2:
Different layers of the acoustic window are assigned different local qualities: the septa are designed with rigid properties optimized for acoustic transparency, while the core layer is designed with elastomeric properties optimized for structural support. This local differentiation allows each layer to perform its specific function optimally without compromising the other.
3Strength
If the core and septa layers are made thick to meet structural requirements in high frequency applications, then structural strength is improved, but acoustic performance deteriorates
Solution Approach 1:
The composite sandwich structure resolves this contradiction by separating the structural and acoustic functions into different layers. The thick elastomeric core layer provides the necessary structural strength for high frequency applications, while the thin rigid septa maintain acoustic transparency. The core layer thickness can be optimized for structural requirements without compromising acoustic performance.
Solution Approach 2:
The invention changes the material parameters by using elastomeric material with specific damping characteristics in the core layer. This material property selection allows the core to be made thicker for structural strength while the damping properties prevent degradation of acoustic performance, effectively decoupling the structural and acoustic optimization parameters.
4Force
If a rigid window structure is used, then structural support to withstand hydrodynamic forces is improved, but noise interference from flow and vibration increases
Solution Approach 1:
The composite structure with rigid septa and elastomeric core provides both hydrodynamic force resistance and noise reduction. The rigid outer layers withstand the hydrodynamic pressures while the elastomeric core layer dampens vibrations and reduces noise generation from water flow, preventing the transmission of mechanical vibrations that would otherwise create noise interference.
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 design effectively transmits high-frequency acoustic signals with minimal distortion and attenuation, while providing sufficient structural support to withstand hydrodynamic forces, improving signal clarity and reducing noise interference.
Implementation Method 1
at least one core layer sandwiched between the septa and including a cellular reinforcement and transmission medium encapsulating the cellular reinforcement
Implementation Method 2
The rigid window can generate and transmit a significant amount of acoustic noise associated with flow of water over the window and arising from vibrational frequencies
Data Source
AI summary
An acoustic window for passage of desired acoustic waveforms therethrough is provided. The acoustic window includes at least a pair of structural septa. At least one core layer is sandwiched between the septa and includes a cellular reinforcement and transmission medium encapsulating the cellular reinforcement. The acoustic window may be included on the hull of a surface or submergible vessel, in order to provide a hydrodynamic fairing over sonar or other acoustic equipment.