Finite element modeling of active cabin noise control problems

Modeling of piezoelectric smart structures applied in a cabin noise problem is studied. Cubic shaped acoustic cavity with flat plate which covers one side is taken as the problem. Noise source locates outside of the box and the noise propagates into the interior region through the plate structure. Disk shaped piezoelectric actuators are mounted on the plate and the actuators are excited. The actuators will generate a proper response to reduce the pressure fields at a certain region in the cavity. The plate structure is modeled using finite element method which is based on a combination of three dimensional piezoelectric, flat shell and transition elements. The transition element connects the three dimensional and flat shell elements. Acoustic cavity is modeled using modal approach which represents the pressure fields in the cavity as a sum of mode shapes of the cavity with unknown coefficients. By using orthogonality of the mode shapes of the cavity, finite element equation for the structure with the influence of acoustic cavity is derived. Once the structure response is found by solving the finite element equation, the pressure fields at the inside of the cavity are recovered directly. Numerical results show the pressure fields at the inside of the box, No activation results are examined at different frequencies to see the feasibility of the proposed modeling approach. When the actuators are activated, the results of pressure fields inside of the cavity show that the cabin noise at a certain zone inside the cavity can be reduced. Future works to improve cabin noise control performance are addressed.