The dependence on electrical power and the advancement of new technology devices has driven new research in the area of alternative energy sources. As electronic devices become smaller and more portable, the use of conventional batteries have become less practical. This has lead to an increase in the study of vibration-based energy harvesting and its use as an alternative source of energy. Previously, linear systems have been developed to harvest energy efficiently when the mechanical oscillator is tuned to the appropriate excitation frequency. This tuning requirement limits the application to a narrow bandwidth of frequencies and puts significant demand on properly designing the system to match a specific excitation. By incorporating nonlinearities in the design and analysis of energy harvesting devices, an increase in the performance of the harvester and versatilely of application can be achieved. This work investigates the role of non-linearities in the mechanical component on the performance of energy harvesting systems, and their advantages compared to a typical linear harvesting system. In particular, an energy harvester that incorporates a piezoelectric element as the attachment and exhibits strong non-linear behavior is analyzed through numerical and analytical simulations, as well as an experimental validation of the simulations. The harvester is subjected to an excitation of ambient vibrations of either a periodic impulsive or harmonic manner. Strong non-linearities are obtained by either the geometric design of the system or by attaching non-linear springs to the primary mass of a spring-mass-damper system. Under certain operating conditions, the resulting unique dynamic behavior of the non-linear system increases the efficiency in comparison to a single degree-of-freedom linear energy harvester. The use of strongly non-linear energy harvesters as vibration absorbers was also investigated. Vibration absorbers have been shown to be efficient over a wide bandwidth of frequencies when multiple non-linear masses are attached to the primary mass of a linear oscillator. In this work, the conventional vibration absorber described by [21], is enhanced by the insertion of an energy harvester in series with with the non-linear spring. The results indicate an increase in the efficiency of the vibration absorber, while simultaneously creating a proficient energy harvester.

This book is a single-source guide to nonlinearity and nonlinear techniques in energy harvesting, with a focus on vibration energy harvesters for micro and nanoscale applications. The authors demonstrate that whereas nonlinearity was avoided as an undesirable phenomenon in early energy harvesters, now it can be used as an essential part of these systems. Readers will benefit from an overview of nonlinear techniques and applications, as well as deeper insight into methods of analysis and modeling of energy harvesters, employing different nonlinearities. The role of nonlinearity due to different aspects of an energy harvester is discussed, including nonlinearity due to mechanical-to-electrical conversion, nonlinearity due to conditioning electronic circuits, nonlinearity due to novel materials (e.g., graphene), etc. Coverage includes tutorial introductions to MEMS and NEMS technology, as well as a wide range of applications, such as nonlinear oscillators and transducers for energy harvesters and electronic conditioning circuits for effective energy processing.

The transformation of vibrations into electric energy through the use of piezoelectric devices is an exciting and rapidly developing area of research with a widening range of applications constantly materialising. With Piezoelectric Energy Harvesting, world-leading researchers provide a timely and comprehensive coverage of the electromechanical modelling and applications of piezoelectric energy harvesters. They present principal modelling approaches, synthesizing fundamental material related to mechanical, aerospace, civil, electrical and materials engineering disciplines for vibration-based energy harvesting using piezoelectric transduction. Piezoelectric Energy Harvesting provides the first comprehensive treatment of distributed-parameter electromechanical modelling for piezoelectric energy harvesting with extensive case studies including experimental validations, and is the first book to address modelling of various forms of excitation in piezoelectric energy harvesting, ranging from airflow excitation to moving loads, thus ensuring its relevance to engineers in fields as disparate as aerospace engineering and civil engineering. Coverage includes: Analytical and approximate analytical distributed-parameter electromechanical models with illustrative theoretical case studies as well as extensive experimental validations Several problems of piezoelectric energy harvesting ranging from simple harmonic excitation to random vibrations Details of introducing and modelling piezoelectric coupling for various problems Modelling and exploiting nonlinear dynamics for performance enhancement, supported with experimental verifications Applications ranging from moving load excitation of slender bridges to airflow excitation of aeroelastic sections A review of standard nonlinear energy harvesting circuits with modelling aspects.

The vast reduction in size and power consumption of CMOS circuitry has led to a large research effort based around the vision of wireless sensor networks. The proposed networks will be comprised of thousands of small wireless nodes that operate in a multi-hop fashion, replacing long transmission distances with many low power, low cost wireless devices. The result will be the creation of an intelligent environment responding to its inhabitants and ambient conditions. Wireless devices currently being designed and built for use in such environments typically run on batteries. However, as the networks increase in number and the devices decrease in size, the replacement of depleted batteries will not be practical. The cost of replacing batteries in a few devices that make up a small network about once per year is modest. However, the cost of replacing thousands of devices in a single building annually, some of which are in areas difficult to access, is simply not practical. Another approach would be to use a battery that is large enough to last the entire lifetime of the wireless sensor device. However, a battery large enough to last the lifetime of the device would dominate the overall system size and cost, and thus is not very attractive. Alternative methods of powering the devices that will make up the wireless networks are desperately needed.

The concept of harvesting electrical energy from ambient vibration sources has been a popular topic of research in recent years. The motivation behind this research is largely due to recent advancements in microelectromechanical systems (MEMS) technology - specifically the construction of small low powered sensors which are capable of being placed in inaccessible or hostile environments. The main drawback with these devices is that they require an external power source. For example, if one considers large networks of low powered sensors (such as those which may be attached to a bridge as part of a structural health monitoring system) then one can envisage a scenario where energy harvesters are used to transfer the vibration energy of the bridge into electrical energy for the sensors. This would alleviate the need for batteries which, in this scenario, would be difficult to replace. Initial energy harvester designs suffered from a major flaw: they were only able to produce useful amounts of power if they were excited close to their resonant frequency. This narrow bandwidth of operation meant that they were poorly suited to harvesting energy from ambient vibration sources which are often broadband and have time dependent dominant frequencies. This led researchers to consider the concept of nonlinear energy harvesting - the hypothesis that the performance of energy harvesters could be improved via the deliberate introduction of dynamic nonlinearities. This forms the main focus of the work in this thesis. The first major part of this work is concerned with the development of an experimentally validated physical-law based model of an electromagnetic energy harvester with Duffing-type nonlinearities. To this end, a self-adaptive differential evolution vi (SADE) algorithm is used in conjunction with experimental data to estimate the parameters needed to accurately model the behaviour of the device. During this investigation it is found that the response of the energy harvesting device in question is very sensitive to the effects of friction. Consequently, a detailed study is undertaken with the aim of finding whether the model performance could be improved by accounting for this complex nonlinear phenomenon. After investigating several different friction models, a reliable and extensively validated digital model of a nonlinear energy harvesting device is realised. With the appropriate equations of motion identified, analytical approximation methods are used to analyse the response of the device to sinusoidal excitations. The motivation for the second main part of this work arises from the fact that ambient excitations are often stochastic in nature. As a result, much of the work in this section is directed towards gaining an understanding of how nonlinear energy harvesters respond to random excitations. This is an interesting problem because, as a result of the random excitation, it is impossible to say exactly how such a device will respond - the problem must be tackled using a probabilistic approach. To this end, the Fokker-Planck-Kolmogorov (FPK) equation is used to develop probability density functions describing how the nonlinear energy harvester in question responds to Gaussian white noise excitations. By conducting this analysis, previously unrecognised benefits of Duffing-type nonlinearities in energy harvesters are identified along with important findings with regards to device electrical optimisation. As for friction effects, the technique of equivalent linearisation is employed alongside known solutions of the FPK equation to develop expressions approximating the effect of friction on randomly excited energy harvesters. These results are then validated using Monte-Carlo methods thus revealing important results about the interaction between Duffing-type and friction nonlinearities. Having investigated sinusoidal and random excitations, the final part of this work focuses on the application of nonlinear energy harvesting techniques to real energy harvesting scenarios. Excitation data from human walking motion and bridge vibrations is used to excite digital models of a variety of recently proposed nonlinear energy harvesters. This analysis reveals important information with respect to how well energy harvesting solutions developed under the assumption of Gaussian white noise excitations can be extended to real world scenarios.

Energy Harvesting Technologies provides a cohesive overview of the fundamentals and current developments in the field of energy harvesting. In a well-organized structure, this volume discusses basic principles for the design and fabrication of bulk and MEMS based vibration energy systems, theory and design rules required for fabrication of efficient electronics, in addition to recent findings in thermoelectric energy harvesting systems. Combining leading research from both academia and industry onto a single platform, Energy Harvesting Technologies serves as an important reference for researchers and engineers involved with power sources, sensor networks and smart materials.

Vibrations are a part of our environment and daily life. Many of them are useful and are needed for many purposes, one of the best example being the hearing system. Nevertheless, vibrations are often undesirable and have to be suppressed or reduced, as they may be harmful to structures by generating damages or compromise the comfort of users through noise generation of mechanical wave transmission to the body. the purpose of this book is to present basic and advanced methods for efficiently controlling the vibrations and limiting their effects. Open-access publishing is an extraordinary opportunity for a wide dissemination of high quality research. This book is not an exception to this, and I am proud to introduce the works performed by experts from all over the world.

Frequency Analysis of Vibration Energy Harvesting Systems aims to present unique frequency response methods for analyzing and improving vibration energy harvesting systems. Vibration energy is usually converted into heat energy, which is transferred to and wasted in the environment. If this vibration energy can be converted into useful electric energy, both the performance and energy efficiency of machines, vehicles, and structures will be improved, and new opportunities will open up for powering electronic devices. To make use of ambient vibration energy, an effective analysis and design method is established and developed in this book. The book covers a wide range of frequency response analysis methods and includes details of a variety of real-life applications. MATLAB programming is introduced in the first two chapters and used in selected methods throughout the book. Using the methods studied, readers will learn how to analyze and optimize the efficiency of vibration energy systems. This book will be ideal for postgraduate students and researchers in mechanical and energy engineering.

This book presents a selection of contributions from the 4th International Conference on Structural Nonlinear Dynamics and Diagnostics, reflecting diverse aspects of nonlinear and complex dynamics. Fifteen chapters discuss the latest findings and applications in active research areas in nonlinear mechanics and physics. These includes the dynamics of ships with liquid sloshing interaction, dynamics of drops and bubbles, nonlinear drying processes, suppression of time-delayed induced vibrations, dynamics of robotic systems, chaos detection in rolling element, dynamics of a planetary gear system with faults, vibro-impact systems, complex fractional moments for nonlinear systems, oscillations under hysteretic conditions, as well as topics in nonlinear energy harvesting and control.