Experimental and numerical study of MIMO active vibration control

In this paper the finite element method is used for choosing the best position of nearby collocated pairs of actuator-sensor couples, an experimental investigation of active vibration control validates the theory; the application regards a rectangular sandwich laminated plate (carbon-epoxy outer skins and Nomex paper honeycomb core) with free boundary conditions. The piezoelectric unidirectional patches are used as strain sensors and strain actuators, respectively. The collocation of the patches is led by the results of a finite element modal analysis and allows the design of a modal control strategy, the efficiency of which is targeted to single vibration modes. The control configurations presented in this paper is a MIMO configuration in linear field. The identification activity and the extraction of stabilised transfer functions are performed by means of a dedicated Matlab algorithm. The stability and the robustness of the algorithm are briefly studied. A substantial reduction of the vibration amplitude is obtained both at specific frequencies and in a broadband random excitation-disturbance. It is also possible to control disturbances that would otherwise trigger geometrically nonlinear vibrations. The modal character of the resulting control is guaranteed by means of the MAC. An experimental setup has been developed, two to four Macro Fiber Composite (MFC) actuators and two MFC sensors are used in conjunction with a DSPACE controller system. The control appears robust and efficient in reducing vibration levels in linear and nonlinear field, even though the structure under investigation exhibits a high modal density, four resonances in a range of about 100Hz, and allows controlling each resonance separately or together.