Reduction of Noise Loads in Rotorcraft Interior Using Poroelastic Materials

Abstract

Operators of military vehicles are subject to harsh noise loads. In some cases this is severe enough to warrant long-term health impacts; in order to avoid this, restricted operating hours for various noise levels are prescribed. In case of rotorcraft vehicles, both the rotor and its driving engine are serious sources of noise, therefore the crew can only spend their operating hours using (active or passive) hearing protection headphones or helmets. Since sound pressure level peaks from the primary noise sources are in the low-frequency range, the application of poroelastic and solid damping materials for interior noise reduction will be investigated using the finite element method. In order to do so, a helicopter interior model is simulated without acoustic damping materials and with the use of solid damping materials as well. Sound pressure level reduction shown in the results increases service time in the vehicle and reduces noise-induced fatigue of occupants.