Application of Acoustic Black Holes To Rotorcraft Structures for Vibration and Noise Control
Open Access
Author:
Veltre, Robert Anthony
Area of Honors:
Aerospace Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Stephen Clarke Conlon, Thesis Supervisor Dr. George A Lesieutre, Thesis Honors Advisor
Keywords:
Acoustics Vibration Aerospace Rotorcraft
Abstract:
In recent years, acoustic black holes have proven to be effective vibration damping and transmission loss mechanisms. By tapering the local thickness of the structure, the black holes are able to reduce the bending wave speed thereby focusing strain energy into localized viscoelastic damping. This improves the efficiency of the applied damping layers. Due to their promising potential to both reduce weight and enhance damping, acoustic black holes have a multitude of vehicle born applications. Interior noise reduction in rotorcraft is a prominent application due to the presence of gear meshing noise. In this work, the application of acoustic black hole treatments applied to plates and sandwich panel structures is evaluated computationally using the finite element method. These notional structures were evaluated over the frequency range of sound commonly transmitted by rotorcraft transmission systems. These results are then compared with results given by uniform plates and sandwich panels of similar dimensions. The results indicate that acoustic black holes reduce vibration in the aluminum sandwich panels by 10 dB compared to traditional damping approaches, while reducing weight.
