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The present work relates to the assessment and testing of a multifunctional intelligent system, based upon the use of piezoelectric devices, devoted both to the active noise and vibration control and to damage detection f the structure. In the control application, the piezoelectric devices (in form of patches) play the role of actuators; their induced secondary vibration field has the target to reduce the primary one through a specific control algorithm and system. In the health monitoring application, the piezo devices play both the roles of actuators and sensors. In fact the developed technique is primarily based upon the evaluation and comparison of the structure Frequency Response Functions (FRF) that intrinsically contains all the information regarding the structural properties whose change may be correlated with incipient damages. The aforementioned application were investigated and experimentally assessed with good results with reference to a typical partial fuselage structure (three frames, eight stringers and the skin panels: 1.2 m x 1.7 m). On the noise control application side, a height sensors/height actuators control architecture was then assessed and experimentally tested whose results may be synthesized in a 30 dB vibration level reduction at sensors locations and more than 20 dB of reduction of the associated noise field. In the optic of a multifunctional intelligent system, the aforementioned set of piezo's was decided to be used also for health monitoring application. As a preliminary activity, an extensive monitoring was performed on the integer structure to verify the sensibility of the system and the stability of the defined Damage Index (DI) in respect to environmental factor not related to structural real modification. To verify the sensibility of the technique to reveal and locate a typical shear clip damage, a set of rivets were successively cut in the area surrounding the frame shear clip, and relative FRF's were acquired and relative DI calculated. The analysis of the data showed a good sensibility of the system to identify the presence of a damage with maximum values of the DI in the sensor closest to the damage location and with an absolute value of the index growing up with damage extension.
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