Geometric Nonlinear Finite Element and Genetic Algorithm Based Vibration Energy Harvesting from Functionally Graded Nonprismatic Piezolaminated Beams

Energy harvesting technology has the ability to create autonomous, self-powered systems which do not rely on the conventional battery for their operation. The term energy harvesting is the process of converting the ambient energy surrounding a system into some useful electrical energy using certain materials. Among several energy conversion techniques, the conversion of ambient vibration energy to electrical energy using piezoelectric materials has great deal of importance which encompasses electromechanical coupling between mechanical and electrical domains. The energy harvesting systems are designed by incorporating the piezoelectric materials in the host structure located in vibration rich environment. The work presented in this dissertation focuses on upgrading the concept of energy harvesting in order to engender more power than conventional energy harvesting designs. The present work deals with first the finite element (FE) formulation for coupled thermo-electro-mechanical analysis of vibration energy harvesting from an axially functionally graded (FG) non-prismatic piezolaminated cantilever beam. A two noded beam element with two degrees of freedom (DOF) at each node has been used in the FE formulation. The FG material (i.e. non-homogeneity) in the axial direction has been considered which varies (continuously decreasing from root to tip of such cantilever beam) using a proposed power law formula. The various cross section profiles (such as linear, parabolic and cubic) have been modelled using the Euler-Bernoulli beam theory and Hamilton‘s principle is used to solve the governing equation of motion. The simultaneous variation of tapers (both width and height in length directions) is incorporated in the mathematical formulation. The FE formulation developed in the present work has been compared with the analytical solutions subjected to mechanical, electrical, thermal and thermo-electro-mechanical loading. Results obtained from the present work shows that the axially FG nonprismatic beam generates more output power than the conventional energy harvesting systems. Further, the work has been focussed towards the nonlinear vibration energy harvesting from an axially FG non-prismatic piezolaminated cantilever beam. Geometric nonlinear based FE formulation using Newmark method in conjunction with Newton-Raphson method has been formulated to solve the obtained governing equation. Moreover, a real code GA based constrained optimization technique has also been proposed to determine the best possible design variables for optimal power harvesting within the allowable limits of ultimate stress of the beam and voltage of the PZT sensor. It is observed that more output power can be obtained based on the present optimization formulation within the allowable limits of stress and voltage than that of selection of design variables by trial and error in FE modelling

Energy Harvesters and Self-powered Sensors for Smart Electronics

This book is a printed edition of the Special Issue “Energy Harvesters and Self-Powered Sensors for Smart Electronics” that was published in Micromachines, which showcases the rapid development of various energy harvesting technologies and novel devices. In the current 5G and Internet of Things (IoT) era, energy demand for numerous and widely distributed IoT nodes has greatly driven the innovation of various energy harvesting technologies, providing key functionalities as energy harvesters (i.e., sustainable power supplies) and/or self-powered sensors for diverse IoT systems. Accordingly, this book includes one editorial and nine research articles to explore different aspects of energy harvesting technologies such as electromagnetic energy harvesters, piezoelectric energy harvesters, and hybrid energy harvesters. The mechanism design, structural optimization, performance improvement, and a wide range of energy harvesting and self-powered monitoring applications have been involved. This book can serve as a guidance for researchers and students who would like to know more about the device design, optimization, and applications of different energy harvesting technologies

Validation of thermodynamic magneto-mechanical finite-element model on cantilever-beam type magnetostrictive energy harvester

This paper presents the validation of a thermodynamic magneto-mechanical model to analyze a galfenol based cantilever beam type energy harvesting device. As compared to some earlier modeling approaches that were tested only on specific harvester geometries, the thermodynamic model has already been validated on rod-type harvesters and is now shown to be suitable for analyzing also beam-type devices. Moreover, the paper discusses the influence of magnetostriction upon resonant frequency. The thermodynamic model is implemented in a 3D finite element solver using COMSOL Multiphysics software. This allows optimizing the device design by tuning the geometric parameters and magnetic bias under available operating conditions (amplitude and frequency of vibrations) easily and efficiently. A unimorph cantilever beam type prototype harvester device consisting of a galfenol beam bonded to an aluminum substrate is constructed for validating the model. Simulated and measured results are compared at base excitation amplitudes of 0.5 to 2 g under varying vibration frequencies. The results show that the maximum induced voltage is obtained at the resonant frequency which decreases slightly with an increase in the vibration amplitude. Furthermore, it is shown that the resonant frequency decreases from 201 Hz to 187 Hz at 1 g base acceleration when the magnetic bias is removed. The comparison of measured and simulated results show that the model can accurately predict the resonant frequency with a relative error of less than 2%, validating the modeling approach. The model can also reasonably determine the open circuit voltage with some discrepancies at large vibration amplitudes.publishedVersionPeer reviewe

Smart Materials and Devices for Energy Harvesting

This book is devoted to energy harvesting from smart materials and devices. It focusses on the latest available techniques recently published by researchers all over the world. Energy Harvesting allows otherwise wasted environmental energy to be converted into electric energy, such as vibrations, wind and solar energy. It is a common experience that the limiting factor for wearable electronics, such as smartphones or wearable bands, or for wireless sensors in harsh environments, is the finite energy stored in onboard batteries. Therefore, the answer to the battery “charge or change” issue is energy harvesting because it converts the energy in the precise location where it is needed. In order to achieve this, suitable smart materials are needed, such as piezoelectrics or magnetostrictives. Moreover, energy harvesting may also be exploited for other crucial applications, such as for the powering of implantable medical/sensing devices for humans and animals. Therefore, energy harvesting from smart materials will become increasingly important in the future. This book provides a broad perspective on this topic for researchers and readers with both physics and engineering backgrounds

Vibration Energy Harvesting for Wireless Sensors

Kinetic energy harvesters are a viable means of supplying low-power autonomous electronic systems for the remote sensing of operations. In this Special Issue, through twelve diverse contributions, some of the contemporary challenges, solutions and insights around the outlined issues are captured describing a variety of energy harvesting sources, as well as the need to create numerical and experimental evidence based around them. The breadth and interdisciplinarity of the sector are clearly observed, providing the basis for the development of new sensors, methods of measurement, and importantly, for their potential applications in a wide range of technical sectors

Design and Modelling of a Novel Hybrid Vibration Converter based on Electromagnetic and Magnetoelectric Principles

Supplying wireless sensors from ambient energy is nowadays highly demanded for a higher flexibility of use and low system maintenance costs. Vibration sources are thereby especially attractive due to their availability and the relatively high energy density they can provide. The aim of this work is to realize a hybrid energy converter for vibration sources having low amplitude and low frequency. The idea is to combine two diverse harvesters to realize a higher energy density and at the same time to improve the converter reliability. We focus on the design, modeling, and test of the hybrid vibration converter. For an appropriate converter design, the vibration profiles of several ambient vibration sources are characterized. The results show that the typical frequency and acceleration ranges are between 5 Hz to 60 Hz and 0.1 g to 1.5 g respectively. The proposed converter is based on the magnetoelectric (ME) and electromagnetic (EM) principles. These two principles can be easily combined within almost the same volume, because they generate energy form the same varying magnetic field coupled to the mechanical vibration of the source. Thereby, the energy density is improved as the ME converter is incorporated within the relatively large coil housing of the electromagnetic converter. The proposed converter is based on the use of a magnetic spring instead of the typically used mechanical springs, which applies the repulsive force to the seismic mass of the converter. The applied vibration is transmitted to the converter based on the magnetic spring principle instead of the conventional mechanical springs. Due to the nonlinearity of the magnetic spring, the converter is able to operate for a frequency bandwidth instead of resonant frequency which is the case while using a mechanical spring. Hence, this leads to realize a high converter efficiency even under random vibrations characterized by frequency bandwidth. As well, using magnetic spring principle enables to adjust the resonant frequency of the converter relative to the applied vibration source easily by just adjusting the moving magnet size. For the converter design, a parametric study is conducted using finite element analysis. Two main criteria are thereby taken into account, which are the compactness and the efficiency of the converter. Parameters affecting these two criteria are classified in mechanical, electromagnetic and magnetoelectric parameters. Results show that the combination of the EM and ME principles leads to an improvement of the energy output compared to a single EM or ME converter. The novel hybrid converter is realized and tested under harmonic and real vibration profiles. It comprises two main parts: A fixed part, where the coils and the ME transducer are fixed in order to ensure a good reliability of the converter by avoiding wire movements. A moving part, where the moving magnet of the magnetic spring and the magnetic circuit are placed. The presented converter is reliable and compact, which is able to harvest energy with a maximum output power density of 0.11 mW/cm³ within a frequency bandwidth of 12 Hz for a resonance frequency of 24 Hz under an applied harmonic vibration with an amplitude of 1 mm.Die Versorgung von drahtlosen Sensoren aus der Umgebungsenergie ermöglicht heutzutage eine hohe Einsatzflexibilität und die Senkung des Systemwartungsaufwands. Schwingungsquellen sind aufgrund ihrer Verfügbarkeit und der damit erreichbaren Energiedichte besonders attraktiv. Ziel dieser Arbeit ist es, einen hybriden Energiewandler für Vibrationsquellen mit geringer Amplitude und niedriger Frequenz zu realisieren. Der Ansatz dabei ist, zwei verschiedene Wandler zu kombinieren, um eine höhere Energiedichte zu erreichen und die Zuverlässigkeit zu verbessern. Der Entwurf konzentriert sich auf die Modellierung und den Test des hybriden Vibrationswandlers. Für einen geeigneten Wandlerentwurf werden die Schwingungsprofileigenschaften mehrerer Umgebungsschwingungsquellen untersucht. Die Ergebnisse zeigen, dass die typische Frequenz zwischen 5 Hz und 60 Hz und der Beschleunigungsbereich zwischen 0,1 g und 1,5 g liegen. Der vorgeschlagene Wandler kombiniert das magnetoelektrischen (ME) Prinzip mit dem elektromagnetischen (EM) Prinzip. Diese beiden Prinzipien können innerhalb des fast gleichen Volumens leicht integriert werden, da sie Energie aus der Variation des gleichen Magnetfeldes, das mit der mechanischen Schwingung gekoppelt ist, erzeugen können. Dadurch wird die Energiedichte verbessert, da der ME-Wandler in das relativ große Spulengehäuse des elektromagnetischen Wandlers eingesetzt werden kann. Darüber hinaus basiert der vorgeschlagene Wandler auf der Verwendung von Magnetfedern, um die Repulsivkraft auf die seismische Masse zu realisieren. Aufgrund der Nichtlinearität der Magnetfeder, kann der Wandler in einem breiteren Frequenzbereich betrieben werden, anstatt nur bei der Resonanzfrequenz, wie es bei der Verwendung einer mechanischen Feder der Fall ist. Dies führt dazu, dass der Wandler auch bei zufälligen breitbandigen Schwingungsquellen effizient betrieben werden kann. Darüber hinaus ermöglicht die Verwendung des Magnetfederprinzips eine einfache Einstellung der Resonanzfrequenz des Wandlers in Bezug auf die Schwingungsquelle, durch Einstellen der Größe des beweglichen Magneten. Für den Wandlerentwurf wird eine Parameterstudie mit Hilfe der Finite-Elemente-Analyse durchgeführt. Zwei Hauptkriterien werden dabei berücksichtigt: Die Kompaktheit und die Energieeffizienz des Wandlers. Parameter die diese beiden Kriterien beeinflussen, können in mechanische, elektromagnetische und magnetoelektrische unterteilt werden. Die Ergebnisse haben gezeigt, dass die Kombination der EM- und ME-Prinzipien zu einer Verbesserung der Energieausbeute im Vergleich zu einem einzelnen EM- oder ME-Wandler geführt hat. Der neuartige Hybrid-Wandler wurde realisiert und unter harmonischen und realen Schwingungsprofilen getestet. Der Wandler besteht aus zwei Hauptteilen: Ein festes Teil, an dem die Spulen und der ME-Wandler befestigt sind, um eine hohe Zuverlässigkeit zu gewährleisten indem auf einen beweglichen Draht verzichtet wird, und ein bewegliches Teil, das sich aus einem beweglichen Magneten zusammensetzt. Der vorgestellte Wandler ist zuverlässig, kompakt und in der Lage, Energie mit einer maximalen Ausgangsleistungsdichte von 0,11 mW/cm 3 und einer Bandbreite von 12 Hz bei einer Resonanzfrequenz von 24 Hz unter einer angelegten harmonischen Schwingung mit einer Amplitude von 1 mm zu gewinnen

Energy harvesting using a magnetostrictive transducer based on switching control

In this work, a switching control energy harvesting method using magnetostrictive materials is proposed. By combining a magnetostrictive material, an electric circuit, and an electronic switch, large-scale kinetic to electrical energy conversion can be achieved. The magnetostrictive material, magnet bias, and coils constitute an energy transducer, called a magnetostrictive transducer. The electronic switch strategically controls the switching of the circuit state according to an input switching signal. Using numerical simulations, we optimised the parameters and validated the harvesting performance with experimental measurements using a 3.75 m vibrated cantilever truss structure. In 20.0 s, the proposed method achieved an electrical energy of approximately 45 μJ, which is seven times more than that of the conventional passive method

SUSTAINABLE ENERGY HARVESTING TECHNOLOGIES – PAST, PRESENT AND FUTURE

Chapter 8: Energy Harvesting Technologies: Thick-Film Piezoelectric Microgenerato