Prof. Marcelo Trindade

Analysis, Design and Optimization of Piezoelectric Structures for Vibration Control and Energy Harvesting under Parametric Uncertainties

University of Sao Paolo

This presentation will focus on strategies to deal with environmental, design and manufacturing parametric uncertainties on the analysis, design and optimization of adaptive structures with piezoelectric elements with applications for passive, active and active-passive vibration control and energy harvesting. Piezoelectric materials are widely used as distributed sensors and actuators. Surface-mounted piezoelectric sensors and actuators allow to couple the host structure bending response with electric inputs/outputs. For instance, research has shown that the use of piezoelectric sensors and/or actuators allows effective passive and/or active control of the structural vibrations and can also be used as energy harvesting devices to provide integrated and self-generating energy to power internal electronics. Depending on the electric connections, a surface-mounted piezoelectric patch may suit different applications, such as passive, active and active-passive vibration control, named as Piezoelectric Shunt Damping (PSD), Active Structural Control (ASC), Active-Passive Piezoelectric Networks (APPN), respectively, and Energy Harvesting (EH) that could be electromechanically enhanced by adding electric circuits to the harvesting ones, leading to an Enhanced Energy Harvesting (EEH). The connection of piezoelectric patches to shunt circuits allows to control the electrical energy induced in the shunt circuit due to electromechanical coupling. Most of the recent studies focus on optimizing the shunt circuits by including resistances, inductances, capacitances and switches in series and/or parallel. Research was also directed to combined active and passive vibration control techniques, such as the so-called Active-Passive Piezoelectric Networks (APPN) that integrates an active voltage source with a passive resistance-inductance shunt circuit to a piezoelectric sensor/actuator, allowing to simultaneously dissipate passively vibratory energy through the shunt circuit and actively control the structural vibrations. As for their use as energy harvesting devices, most studies explore the use of eletromechanical resonant devices tuned to the operating frequency of a host structure or machine in order to maximize the electrical energy harvested. Usually, they are based on a cantilever beam with tip mass whose properties are tuned accordingly so that the device resonance frequency matches the operating frequency. The electrical energy is generated by one or more piezoelectric patches bonded to a cantilever beam. Through their electrodes, piezoelectric patches can convert part of their strain energy into useful electrical energy. This induced electric current should be directed to a proper electric circuit responsible for signal rectification and energy storage. The performance of piezoelectric patches for these types of applications are very much dependent on the adequate tuning between resonant, circuit and operation frequencies and on the effective electromechanical coupling between patches and host structure. Therefore, variabilities and/or uncertainties on environmental conditions, material properties, boundary conditions and bonding effectiveness have a major effect on reducing the expected or predicted performance of such devices. However, few studies have attempted to analyze the effect of parametric uncertainties on active and/or passive vibration control and energy harvesting performance. Hence, recent results on strategies to deal with parametric uncertainties on the analysis, design and optimization of adaptive piezoelectric structures will be presented. The presentation will discuss methodologies to account for uncertainties in analysis and design, such as stochastic modeling, uncertainty estimation, quantification and propagation, and well-adapted strategies for robust optimization and design of such structures. The discussed applications will include the analysis and quantification of the effects of piezoelectric material properties uncertainties on vibration control and energy harvesting; piezoelectric sensors positioning and gain on spatial modal filters; adhesive layer uncertainties on electromechanical coupling, vibration control and energy harvesting; electric circuit uncertainties on piezoelectric shunted damping; and environmental and manufacturing uncertainties on the robust optimization of piezoelectric energy harvesters.