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Acoustic scattering by finite composite plates.
Maurício M Nilton1, André V G Cavalieri1, Maurício V Donadon1
1Divisão de Engenharia Aeronáutica, Instituto Tecnológico de Aeronáutica, São José dos Campos, São Paulo, 12228-900, Brazil.
The Journal of the Acoustical Society of America
|November 15, 2018
Summary
Anisotropic composite plates significantly reduce sound scattering from trailing edges. This acoustic advantage stems from their lower mass and enhanced elasticity effects, outperforming metallic plates.
Area of Science:
- Acoustics
- Materials Science
- Structural Mechanics
Background:
- Trailing edge scattering is a major source of aerodynamic noise.
- Elasticity reduces radiated sound via coupled acoustic and bending waves.
- Existing analyses are primarily limited to isotropic materials.
Purpose of the Study:
- To extend numerical methods for analyzing acoustic scattering from anisotropic composite plates.
- To investigate the influence of ply orientation and stacking sequence on sound reduction.
- To compare the acoustic performance of composite laminates with metallic plates.
Main Methods:
- A boundary element method (BEM) was adapted for anisotropic symmetric laminates.
- Hierarchical finite element method (FEM) was used to derive vibration modes.
- Expressions for bending waves in composite plates were formulated.
Main Results:
- The numerical method successfully accounts for anisotropic plate behavior.
- Ply orientation and stacking sequence significantly modify scattered sound.
- Composite laminates demonstrate lower acoustic scattering than equivalent metallic plates.
Conclusions:
- Anisotropic composite plates offer substantial reductions in trailing edge noise.
- Lower specific mass in composites enhances fluid-solid coupling and elasticity effects.
- Composite materials present an advantageous solution for noise reduction applications.
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