VIBRO-ACOUSTIC ANALYSIS OF MULTI-LAYER CYLINDRICAL SHELL-CAVITY SYSTEMS VIA CUF FINITE ELEMENTS

The understanding of the vibro-acoustic behaviour of the aircraft structure is an important step in order to reduce the noise and vibration (N&V) of aircraft itself. A powerful tool is the well-known Finite Element Method (FEM), which allows to study the vibro-acoustic problem in the low frequency range. The FEM applied to vibro-acoustic has a limitation: to increase the frequency range, it is necessary to decrease the size of the elements. Therefore, in order to study complex model as an aircraft structure, the maximum frequency is often too low to have useful results. Moreover, the exploitation in the aeronautical field of multi-layer and sandwich materials with visco-elastic core, leads to the decrease of accuracy of classical shell elements and the need to often adopt solid elements, further increasing the size of the FEM problem. In this work we exploit a powerful notation for shells, the Carrera's unified formulation (CUF), to reduce the size of the vibro-acoustic problem. Curvilinear shell elements are applied to a cylindrical structure, similar to a fuselage, to study different materials, without increasing the size of the problem or losing accuracy in the solution. In this way it will be possible to reach higher frequency in the vibro-acoustic analysis, still describing the behaviour of sandwich and composite structures with the same accuracy of the solid elements.