A new multi-switch circuit with adaptive capacitance for semi-active piezoelectric shunt damping

Piezoelectric-based shunt dampers are developed in recent years because of simplicity in comparison with other methods. In these methods, a part of converted mechanical energy is stored in the internal electrostatic field of the piezoelectric and a minor portion is dissipated in the load resistor of damping circuits. In recent methods, the electrostatic field of piezoelectric elements is reduced (not eliminated) and a portion (not whole) of the stored energy is extracted and dissipated in the resistor. In this paper, using a new adaptive multi-switch network and RLC resonance concept, the electrostatic field of piezoelectric is eliminated (not reduced) and almost the whole converted energy(not a portion) is extracted and dissipated in the load resistor. Using the proposed network, self-tuning ability provides electrical resonance in the circuit for almost all excitation types in a wide frequency band and also any mass and stiffness of the structure. Most of the electronic damping techniques are presented just for harmonic excitations, but the proposed technique in the current work is suitable for both harmonic and random excitations. In mechanical structures with variable mass such as vehicles, airplanes and missiles, structure mass will be changed while motioning. For such systems, resonance frequencies will change by structure mass during operation. Recent RLC dampers are not self-tuning for different mechanical stiffness or mass, but, the proposed technique is completely adaptive with variable mechanical characteristics of the vibrating structure. Consequently, significant damping is obtainable in comparison with other electronic damping techniques.