Composite Laminate Damping Layer for Aircraft Noise Reduction
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Solution Overview
Problem
Existing composite materials used in aircraft structures, particularly thin and lightweight composites, tend to resonate and generate noise due to fluid flow, leading to reduced service lifetime and increased weight issues when conventional damping methods are applied, such as constrained layer damping, which significantly increases weight and may not be suitable for highly curved regions.
Innovation Solution
A method of forming a curable laminate vehicle body shell component with a majority of structural layers and a minority of damping layers, where the structural layers provide a constraining effect for the damping layer, allowing for effective noise damping without substantial weight increase, by immersing a fibrous open web material in a damping solution and curing the laminate under elevated temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If constrained layer damping is applied to composite materials, then noise damping is improved, but weight increases significantly
Solution Approach 1:
The patent combines the structural layer and damping layer into a single integrated laminate structure, where multiple layers of composite material serve both structural and damping functions simultaneously, eliminating the need for separate constrained layer damping treatments
Solution Approach 2:
The patent uses multi-layer composite laminate structures where alternating structural and damping layers work together to provide both mechanical strength and noise damping, achieving effective damping without the weight penalty of traditional constrained layer damping
2Object-generated harmful factors
If constrained layer damping is applied to composite materials, then noise damping is improved, but the applied layer cannot conform to highly curved regions
Solution Approach 1:
The patent divides the damping function into multiple thin alternating layers within the laminate structure, allowing each layer to conform to curved surfaces independently while collectively providing effective noise damping across complex geometries
Solution Approach 2:
The patent uses thin film-like damping layers within the laminate that can flex and conform to highly curved and convex regions, unlike rigid constrained layer damping products
3Object-generated harmful factors
If multiple damping layers are introduced internally, then noise damping is improved, but the laminate becomes very thick and mechanical strength decreases
Solution Approach 1:
The patent optimizes the local distribution and thickness of damping layers within the laminate, placing damping material only where needed for noise control while maintaining structural integrity in load-bearing regions
Solution Approach 2:
The patent changes the parameters of the damping layers (thickness, material properties, arrangement) to achieve effective noise damping while maintaining optimal mechanical strength, avoiding the need for excessive damping layer quantity
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 approach achieves noise damping comparable to post-cure constrained layer techniques with significantly reduced weight and maintains mechanical integrity, allowing for wide-area coverage regardless of curvature, while minimizing the impairment of mechanical strength.
Implementation Method 1
The viscous properties of the viscoelastic layer dissipate the vibration by converting it to heat
Implementation Method 2
removing the solvent by evaporation
Implementation Method 3
exposing the laminate to elevated temperature and optionally elevated pressure, thereby to cure the laminate
Data Source
Figure 1~3
AI summary
There is provided a method of constructing a laminate vehicle body shell component, comprising forming a damping prepreg or semipreg comprising a sheet-like curable prepreg or semipreg comprising resin and structural fibres having intimately contacted thereto a damping layer (14), wherein the damping layer (14) is formed by immersing a fibrous open web material in a solution of damping material and removing the solvent by evaporation, laying down the damping prepreg or semipreg, and forming the damping prepreg or semipreg into the eventual shape of the body shell component; either before or after, laying down additional fibre structural layers (12, 16) to form a curable laminate vehicle body shell component, then exposing the laminate to elevated temperature and optionally elevated pressure, thereby to cure the laminate to produce the laminate vehicle body shell component.