Bös J., Mayer D.

A semi-active tuned vibration absorber based on a shunted piezoelectric transducer is to be applied to a thin aluminum plate, which forms one side panel of a box made of acrylic glass, to reduce its vibration and sound radiation. For this purpose, an FE model of the plate is created, to which an FE model of a piezoceramic patch is attached. In various computation runs, varying the position, the size, and the thickness of the piezo patch, an optimal configuration is found that maximizes the generalized electromechanical coupling coefficient, a measure for the transformation of electrical energy into mechanical energy and vice versa, for the first vibration mode. From the thus determined size of the patch, which is actually mounted to the plate, its capacitance can be calculated or measured. Likewise, optimal values for a resistance and an inductance can be calculated that, together with the piezo patch’s capacitance, form an oscillating circuit which is tuned so as to influence the first vibration mode of the plate. This circuit is then actually built in hardware using a generalized impedance converter as a synthetic inductance. The effect of this semi-active tuned vibration absorber on the vibration and sound radiation behavior of the plate is demonstrated by means of scanning laser vibrometer and nearfield acoustic holography measurements, respectively, using both loudspeaker and impulse hammer excitation. The velocity amplitude of the first vibration mode is reduced by up to 9 dB, the radiated sound pressure level by approximately 20 dB.