Semi-passive noise isolation of a smart board with embedded piezoelectric elements

The semi-passive control method was used in the noise isolation of a smart board and compared with passive and active methods. Smart board is a composite board of Glass Fiber Reinforced Plastic (GFRP) with five embedded piezoelectric elements. In the semi-passive control method, an inductance and a switching circuit were connected to the piezoelectric elements to dissipate the generated energy. The function of the switching circuit is to boost the energy consumption by increasing the voltage over the piezoelectric elements. In the passive method, a RC shunting circuit was used to dissipate the energy generated by piezoelectric elements. The active control is an adaptive method based on FIR filter and filtered-X LMS algorithm. The control effects of the three methods on the first resonance mode were investigated under sweeping excitation. For a slow sweeping excitation, the damping reaches 6.1 dB with semi-passive control, 14.6 dB with active control and 6.5 dB with passive control around the first resonance frequency. The damping with active control and semi-passive control decreases when the sweeping speed increases.