Piezoelectric materials have been investigated for vibration control in various engineering applications. Passive and active control techniques using piezoelectric materials are among the most important ones in the literature of vibration control. However, passive techniques present a good performance over a narrow frequency bandwidth. On the other hand, although active techniques require external power sources, sensor and actuators, they usually provide a good control performance over a wider range of frequency. To overcome the drawbacks of passive and active techniques, authors have focused on the nonlinear treatment of voltage output of the piezoelectric materials. A particular nonlinear technique, named Synchronized Switch Stiffness Control (SSSC), changes the stiffness of the structure through softening or hardening nonlinearities. The motivation is to ensure that the structure is excited out of its resonance frequency, preventing large displacements. The use of the SSSC technique has already been reported in the literature. However, few works show a circuitry that reproduces the SSSC technique. Furthermore, reported SSSC topologies allow only a hardening or softening effects. This work presents a novel adaptive SSSC piezoelectric circuit that combines the hardening and softening effects, significantly reducing mechanical amplitudes over a wide range of frequencies. The proposed SSSC circuit uses two piezoceramic patches (one as sensor and one as the stiffness actuator) and two symmetrical voltage sources. In the final version of the paper, experimental verifications of numerical predictions will be provided.
Various researchers have investigated the behavior of a linear oscillator weakly coupled to a nonlinear mechanical attachment that has essential stiffness nonlinearity. Under certain conditions, the essentially nonlinear attachment can act as a nonlinear energy sink (NES) and the irreversible transfer of vibration energy from a main structure to the nonlinear attachment is observed. Another characteristic of an essentially nonlinear attachment is the nonexistence of a resonance frequency. Therefore, nonlinear energy sinks have increased robustness against detuning. While mechanical nonlinear attachments are usually linked to a host structure by nonlinear mechanical elements, linear coupling (piezoelectric transduction) is observed in piezoelectric based nonlinear energy sinks and nonlinearity can be achieved through electrical circuit design. This work presents an experimentally validated piezoelectric based nonlinear energy sink. An essentially nonlinear piezoelectric shunt circuit and its practical realization are discussed in detail. The circuit nonlinear behavior and the performance of the piezoelectric nonlinear energy sink to attenuate vibrations of a cantilever over a wide range of frequencies are experimentally validated.
Different methods for suppressing random (turbulence induced) vibrations of a plate like wing with embedded piezoceramics are investigated. An electromechanically coupled finite element model (that accounts different external circuits) is combined with unsteady aerodynamic models (the doublet-lattice method and Roger’s model) to develop a
piezoaeroelastic model of cantilevered plates representing wing-like structures. An atmospheric turbulence model (Von-Karman’s and Dryden’s spectrum) is used to induce random vibrations at different airflow speeds. An active controller and different piezoelectric shunt circuits – passive and hybrid (combining passive circuits and voltage sources – are applied to suppress random vibrations over a range of airflow speeds when a single pair of piezoceramics is modeled on the clamped end of the plate. The behavior of the piezoaeroelastic system is investigated in time and frequency domains. Simulation results demonstrate that the hybrid control approach is more effective than purely passive or active controllers.