Optimal design of tonal noise control inside smart-stiffened cylindrical shells

This paper deals with the abatement of noise inside cylindrical cavities bounded by stiffened shells that are impinged by external tonal sound waves. The problem is analysed in a multidisciplinary context, involving interactions among exterior noise field, elastic shell dynamics, interior acoustics and control system. The actuation in the noise control process is performed through piezoelectric patches embedded in the stiffened shell, driven by a control law obtained from an optimal LQR cyclic control formulation, coupled with a genetic optimization algorithm (GA). A modal approach is applied to describe the smart shell dynamics and the interior acoustics that are coupled in the acoustoelastic plant model, while the exterior acoustic scattering is predicted through a boundary element method formulation. Numerical results deal with an aeronautical problem concerning a general aviation aircraft cabin impinged by the pressure disturbances emitted by a pair of propellers; in particular, the effectiveness and robustness of the active control law synthesized through the GA is investigated.