Vibration-based energy harvesting using piezoelectric cantilevers has been extensively studied over the past decade. As an alternative to cantilevered harvesters, piezoelectric patch harvesters integrated to thin plates can be more convenient for use in marine, aerospace and automotive applications since these systems are often composed of thin plate-like structures with various boundary conditions. In this paper, we present analytical electroelastic modeling of a piezoelectric energy harvester structurally integrated to a thin plate along with experimental validations. The distributed-parameter electroelastic model of the thin plate with the piezoceramic patch harvester is developed based on Kirchhoff's plate theory for all-four-edges clamped (CCCC) boundary conditions. Closed-form steady-state response expressions for coupled electrical output and structural vibration are obtained under transverse point force excitation. Analytical electroelastic frequency response functions (FRFs) relating the voltage output and vibration response to force input are derived and generalized for different boundary conditions. Experimental validation and extensive theoretical analysis efforts are then presented with a case study employing a thin PZT-5A piezoceramic patch attached on the surface of a rectangular aluminum CCCC plate. The importance of positioning of the piezoceramic patch harvester is discussed through an analysis of dynamic strain distribution on the overall plate surface. The electroelastic model is validated by a comparison of analytical and experimental FRFs for a wide range of resistive electrical boundary conditions. Finally, power generation performance of the structurally integrated piezoceramic patch harvester from multiple vibration modes is investigated analytically and experimentally.

Structural vibrations are the major causes of noise problems, passenger discomforts, and mechanical failures in aerospace, automotive, and marine systems, which are mainly composed of lightweight and flexible plate-like structures. In order to reduce structural vibrations and noise radiations of lightweight structures, passive and active treatments have been used and investigated over the last three decades. Our aim of this article is to review current state-of-the-art of active vibration and noise suppression systems for plate and plate-like structures with various kinds of boundary conditions. The reviewed articles use numerical methods and experimental tools to study different aspects of controller architectures. In particular, the focus is placed on the active vibration and noise control systems utilizing piezoelectric patches as sensors and actuators since their popularity in vibration-based applications has increased significantly during the last two decades. We first classify the controllers according to their architectures, then compare their performance in vibration and noise attenuation, and finally provide suggestions for further progress. The categorization of the information regarding the controller strategies and sensor/actuator configurations for different host structures can be used by the controller designers as a starting point for their specific configuration.

As an alternative to beam-like structures, piezoelectric patch-based energy harvesters attached to thin plates can be readily integrated to plate-like structures in automotive, marine, and aerospace applications, in order to directly exploit structural vibration modes of the host system without mass loading and volumetric occupancy of cantilever attachments. In this paper, a multi-mode equivalent circuit model of a piezo-patch energy harvester integrated to a thin plate is developed and coupled with a standard AC-DC conversion circuit. Equivalent circuit parameters are obtained in two different ways: (1) from the modal analysis solution of a distributed-parameter analytical model and (2) from the finite-element numerical model of the harvester by accounting for two-way coupling. After the analytical modeling effort, multi-mode equivalent circuit representation of the harvester is obtained via electronic circuit simulation software SPICE. Using the SPICE software, electromechanical response of the piezoelectric energy harvester connected to linear and nonlinear circuit elements are computed. Simulation results are validated for the standard AC-AC and AC-DC configurations. For the AC input-AC output problem, voltage frequency response functions are calculated for various resistive loads, and they show excellent agreement with modal analysis-based analytical closed-form solution and with the finite-element model. For the standard ideal AC input-DC output case, a full-wave rectifier and a smoothing capacitor are added to the harvester circuit for conversion of the AC voltage to a stable DC voltage, which is also validated against an existing solution by treating the singlemode plate dynamics as a single-degree-of-freedom system.

The liver harvested from a donor must be preserved and transported to a suitable recipient immediately for a successful liver transplantation. In this process, the preservation period is the most critical, since it is the longest and most tissue damage occurs during this period due to the reduced blood supply to the harvested liver and the change in its temperature. We investigate the effect of preservation period on the dynamic material properties of bovine liver using a viscoelastic model derived from both impact and ramp and hold experiments. First, we measure the storage and loss moduli of bovine liver as a function of excitation frequency using an impact hammer. Second, its time-dependent relaxation modulus is measured separately through ramp and hold experiments performed by a compression device. Third, a Maxwell solid model that successfully imitates the frequency- and time-dependent dynamic responses of bovine liver is developed to estimate the optimum viscoelastic material coefficients by minimizing the error between the experimental data and the corresponding values generated by the model. Finally, the variation in the viscoelastic material coefficients of bovine liver are investigated as a function of preservation period for the liver samples tested 1 h, 2 h, 4 h, 8 h, 12 h, 24 h, 36 h, and 48 h after harvesting. The results of our experiments performed with three animals show that the liver tissue becomes stiffer and more viscous as it spends more time in the preservation cycle.

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Several engineering systems, such as aircraft structures, are composed of load-bearing thin plates that undergo vibrations and employ wireless health, usage, and condition monitoring components, which can be made self-powered using vibrational energy harvesting technologies. Integrated piezoelectric patches can be implemented for enabling self-powered sensors in the neighborhood of plate-based structures. In this work, coupled electroelastic modeling and experimental validations of broadband energy harvesting from structurally integrated piezoelectric patches on a rectangular thin plate are presented. A distributed-parameter electroelastic model for multiple patch–based energy harvesters attached on a thin plate is developed. Closed-form structural and electrical response expressions are derived for multiple vibration modes of a fully clamped thin plate for the series and parallel connection configurations of multiple patch–based energy harvesters. Experimental and analytical case studies are then compared for validating the analytical models of structurally integrated multiple patch–based energy harvesters. It is shown that analytical electroelastic frequency response functions exhibit very good agreement with the experimental frequency response function measurements for the series and parallel connection cases. In addition to offering an effective interface for energy harvesting from two-dimensional thin structures, series and parallel multiple patch–based energy harvester configurations yield effective broadband energy harvesting by combining the electrical outputs of harvester patches for multiple vibration modes.

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