Simon F.

To improve the acoustic comfort into cabins of vehicle (aircraft or car), it can be interesting to class each sub-structure as a panel with simplified geometry (beam, plane panel, shell…). This allows to simulate more easily, with analytic models, the acoustic Transmission Loss (TL) of each structure and so to determine each contribution in the total internal noise. The TL represents the ratio between incident acoustic power applied on the structure and acoustic power radiated on the other side. Nevertheless, models generally consider the case of isotropic or multilayered plane panels (with process of homogenization) or cylinders with/without simple boundary conditions. These models are not suited to realistic structural and trim panels or multilayered windows with internal cavity, which are therefore simulated with Finite Element and Beam methods in low frequency range. Author has developed several analytic models to compute the TL of infinitely wide sandwich panels with multi-layered laminates, in the case of diffused incident field in medium and high frequency ranges. Models consider elastic materials as, for example, homogeneous materials, composite fibres (kevlar, carbon or fibre glass) with resin, visco-elastic materials, honeycombs or foams, described by their stiffness matrix. They satisfy the continuity of displacements and shear stresses at the interface of each layer and use a cinematic approach and written of Lagrange equations. No process of homogenization is realized. This paper deals with a modification of the displacement field applied to previous models (with membrane, bending and shear terms) to take 'curved' multilayered panels into account (generalisation of Love' theory). Tests of validation are led for different types of curved structure from theoretical and experimental bibliographic references. Moreover, the effect of shell radius is analysed through typical aircraft structures to determine real influence of geometry on acoustic TL.