Aircraft Noise Absorbing Material Design
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Solution Overview
Problem
Commercial aircraft cabins experience high noise levels due to air flow past the outer skin and engine noise, which existing sound-deadening materials cannot effectively address without increasing payload weight, making them economically unfeasible for commercial use.
Innovation Solution
A lightweight sound-deadening material with a high-specific-gravity elastomer barrier layer and low-density porous/open-cell absorption layer, providing effective sound insulation with a total weight per unit area of 2 kg/m² or less, suitable for the outer skin of aircraft, particularly in the frontal cabin region where air flow noise is predominant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional sound-deadening material is used to reduce noise in aircraft cabins, then sound insulation is improved, but weight increases making it economically unfeasible
Solution Approach 1:
The sound-deadening material is divided into multiple functional layers: a barrier layer for sound reflection and a porous absorption layer for sound energy dissipation. This segmentation allows each layer to perform its specific function efficiently, achieving effective noise reduction with reduced overall material weight compared to conventional homogeneous materials.
Solution Approach 2:
The invention uses composite material structure combining a non-porous barrier layer (elastomer or plastic) with a porous absorption layer (foam or fiber material). This composite approach leverages the complementary properties of different materials - the barrier layer reflects sound waves while the porous layer absorbs acoustic energy - to achieve superior sound insulation with lower weight.
2Object-affected harmful factors
If high mass material is used for sound-deadening, then sound insulation is improved, but weight per unit area increases
Solution Approach 1:
The invention changes the density parameter distribution across different layers: the barrier layer has high density (specific gravity ≥1) for effective sound reflection, while the absorption layer has very low density (4-50 kg/m³) for sound energy absorption with minimal weight. This parameter optimization achieves effective sound insulation with total weight per unit area of 2 kg/m² or less.
Solution Approach 2:
Different regions of the sound-deadening material have different local properties tailored to their specific functions: the barrier layer positioned adjacent to the outer skin has high specific gravity for sound reflection, while the absorption layer has low density for sound energy dissipation. This local quality differentiation optimizes sound insulation performance while minimizing overall weight.
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
The material achieves significant sound insulation (at least 4 dB/SIL) in the 0.5 to 8 kHz frequency range, reducing noise without the need for high mass or weight, making it suitable for commercial aircraft while maintaining structural integrity and flexibility to fit curved surfaces.
Implementation Method 1
The elastomer material has relatively high specific gravity and therefore serves as barrier layer for incident sound
Implementation Method 2
The absorption layer comprises a porous and/or open-cell material with density of from 4 to 50 kg/m3
Implementation Method 3
This material has very low density, from 4 to 15 kg/m3. Porous and/or open-cell means that the material has cavities connected to the surface
Data Source
AI summary
The invention relates to a material for absorbing noise in aircraft, comprising at least one barrier layer and at least one absorptive layer. The barrier layer is provided with an elastomeric material having a minimum specific density of 1 and a mass per unit area of 1.3 kg/m2 or less while the absorptive layer is equipped with a porous and/or open-cell material having a weight per volume of 4 to 50 kg/m3, preferably 10 to 40 kg/m3, more preferably 15 to 35 kg/m3 even more preferably 20 to 30 kg/m3. The mass per unit area of the sound-absorbing material amounts to 2 kg/m2 or less.