Wave modelling in predictive vibro-acoustics: Applications to rail vehicles and aircraft

Three different predictive methods based on wave descriptions of the acoustic field are presented and used to calculate transmission and radiation properties of typical rail and aerospace structures. First, a transfer matrix method assesses the sound transmission and wavenumbers of composite sandwich fuselage structures in a wide frequency range. The method is computationally effective and can be used for numerical optimization of sandwich lay-ups common in rail and aerospace engineering. Further, an approach for which a small finite element model of a periodic cell is applied to create a statistical model of a near periodic structure is shown to determine transmission and radiation properties of stiffened fuselage structures and an extruded train floor structure. Finally, a novel combination of the waveguide FE method with the Rayleigh-Ritz method is applied to: (i) calculate the transmission through a double wall structure; (ii) again assess the sound transmission of an extruded floor structure and also (iii) determine the sound pressure inside a large section of a rail car excited by external sound sources. All three methods presented can be used to effectively support decision making in the design process of trains and aircraft.