Vibroacoustic performance assessment of aircraft panels in low, mid and high frequency regimes

Abstract

In the present work, vibroacoustic (VA) characteristics, namely sound transmission loss (STL), overall sound pressure levels (OASPLs) of aircraft panels made up of aluminum, composites and fiber metal laminates (FML) are studied. The investigation involves modeling of aircraft panels using finite element method (FEM) for low frequency, Boundary Element Method (BEM) for mid-frequency and statistical energy analysis (SEA) in high-frequency bands. To obtain the VA characteristics of the panels, twin chambers, namely source and receiver are numerically modeled, and the panels are placed in between them. The VA performances of the considered panels under low, mid and high-frequency sound environments are numerically simulated using an infinite duct model. The sound source in low, mid and high frequency is modeled in the source chamber as sound pressure, plane wave and diffusive acoustic field, respectively and the receiver chamber is idealized as an anechoic chamber at the ends. This numerical study helps in understanding the VA behavior of aircraft materials and also minimizes the cost and time involved in conducting experiments. The results are presented in the form of STL and OASPL. From this study, it was found that the aluminum and fiber metal laminates have good VA characteristics when compared to composites in all the three frequency regimes and composite panels behaving better in the mid-frequency region of 200 Hz to 300 Hz than aluminum and fiber metal laminates. An optimization approach for aircraft panels is also presented.