Vibrations at a resonant frequency lead to catastrophic failure or at the very least, shorten the life span of the structure due to fatigue. These problems force engineers to implement damping techniques. Smart materials have been used over two decades to reduced vibration amplitudes. Recently, there has been much research and development on smart materials and structures.
This work introduces an innovative approach for vibration suppression using passively shunted piezolectric materials. Initially linear circuit elements such as resistors, capacitors, and inductances, or building a non-linear circuit with different impedance designs were used. Instead of such elements, a switched electromechanical shunt has been proposed as a method to suppress vibrations of mechanical structures. In this state switching technique, bonded piezoelectric elements are switched from open circuit to closed circuit depending on the voltage produced from the piezoelectric patch. This new shunt circuit utilizes diodes. Diodes are nonlinear circuit elements and vibration amplitude is reduced due to introduction of nonlinearity into the system.
A physics-based electro-mechanical model is developed and validated against experimental results. The smart plate consists of a rectangular aluminum plate modeled in cantilever configuration with surface bonded piezoelectric patches. Basic equations for piezoelectric sensors and actuators are presented. The equation of motion for the plate structure with bonded piezoelectric patch is depicted. The implementation of the circuit is demonstrated analytically and experimentally. The concept is demonstrated on two different modes and vibration peaks are lowered using the above mentioned circuit.
Then a numerical model of the plate with the piezoelectric patch and the circuit is built in Simulink after designing a finite element model in ABAQUS. The data shows the effect of damping in Frequency Response Functions (FRFs) and in the response plots. A state-space model is also developed. Simulations of the model are compared to the experimental results.
The results indicate the feasibility of the smart damping materials for many industrial applications where reducing noise and vibrations are desired. It is clear that the maximum suppression that can be obtained with this method is dependent on the voltage drop across the piezoelectric element.