Simulation and the monte carlo method

Nonlinear Oscillations: Exact Solutions and their Approximations

High-Performance Piezoelectric Energy Harvesters and Their Applications

The last two decades have witnessed several advances in microfabrication technologies and electronics, leading to the development of small, low-power devices for wireless sensing, data transmission, actuation, and medical implants. Unfortunately, the actual implementation of such devices in their respective environment has been hindered by the lack of scalable energy sources that are necessary to power and maintain them. Batteries, which remain the most commonly used power sources, have not kept pace with the demands of these devices, especially in terms of energy density. In light of this challenge, the concept of vibratory energy harvesting has flourished in recent years as a possible alternative to provide a continuous power supply. While linear vibratory energy harvesters have received the majority of the literature’s attention, a significant body of the current research activity is focused on the concept of purposeful inclusion of nonlinearities for broadband transduction. When compared to their linear resonant counterparts, nonlinear energy harvesters have a wider steady-state frequency bandwidth, leading to a common belief that they can be utilized to improve performance in ambient environments. Through a review of the open literature, this paper highlights the role of nonlinearities in the transduction of energy harvesters under different types of excitations and investigates the conditions, in terms of excitation nature and potential shape, under which such nonlinearities can be beneficial for energy harvesting. [DOI: 10.1115/1.4026278]

On the Role of Nonlinearities in Vibratory Energy Harvesting: A Critical Review and Discussion

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Stochastic Processes And Filtering Theory

We report here enhanced ferroelectric crystal formation and energy generation properties of polyvinylidene fluoride (PVDF) in the presence of surface-modified crystalline nanocellulose. Incorporation of only 2–5 wt % fluorinated nanocellulose (FNC) in PVDF has been found to significantly induce polar β/γ-phase crystallization as compared to the addition of unmodified nanocellulose (carboxylated nanocellulose). A device made up of electrically poled PVDF/FNC composite films yielded 2 orders of magnitude higher voltage output than neat PVDF in vibrational energy harvesting. This remarkable increase in energy generation properties of PVDF at such a low loading of an organic natural biopolymer could be attributed to the tailored surface chemistry of nanocellulose, facilitating strong interfacial interactions between PVDF and FNC. Interestingly, energy harvesting devices fabricated from PVDF/FNC nanocomposites charged a 4.7 μF capacitor at significantly faster rate and the accumulated voltage on capacitor was 3.8 times greater than neat PVDF. The fact that PVDF/FNC nanocomposites still retain a strain at break of 10–15% and can charge a capacitor in few seconds suggests potential use of these nanocomposites as flexible energy harvesting materials at large strain conditions.

Fluorinated Nanocellulose-Reinforced All-Organic Flexible Ferroelectric Nanocomposites for Energy Generation C

Dynamic vibration absorbers (DVAs) have proven to be an effective passive technique to suppress device vibration, with many realistic implementations in structures, buildings, and machines. Vibration energy harvesting is a process used to convert unwanted vibrations of a host structure into electrical energy. In this paper, a harmonic single degree-of-freedom system is considered consisting of a pendulum absorber and electromagnetic energy harvesting transduction mechanism. These types of DVAs are suitable for control of multi-story buildings, where for the simplicity of analysis a two degree-of-freedom system which models the building with the absorber is considered. Controlling the vibrations of buildings is the primary objective, and harvesting the energy from the dynamic vibration pendulum absorber at the same time is the secondary objective. Parametric analyses are performed. It is observed that proper system parameter selection is key for reducing the vibration amplitude of the primary system and for enhancing the energy harvested from the secondary system. Optimization analysis based on the genetic algorithm approach is used to optimize the system parameters. It is observed that with a proper selection of parameters, wideband energy can be harvested along with reduction in vibration of the building.

Energy Harvesting From Dynamic Vibration Pendulum Absorber

Tuned liquid column dampers have been proved to be successful in mitigating the dynamic responses of civil infrastructure. There have been some recent applications of this concept on wind turbines and this passive control system can help to mitigate responses of offshore floating platforms and wave devices. The control of dynamic responses of these devices is important for reducing loads on structural elements and facilitating operations and maintenance (O&M) activities. This paper outlines the use of a tuned single liquid column damper for the control of a tension leg platform supported wind turbine. Theoretical studies were carried out and a scaled model was tested in a wave basin to assess the performance of the damper. The tests on the model presented in this paper correspond to a platform with a very low natural frequency for surge, sway and yaw motions. For practical purposes, it was not possible to tune the liquid damper exactly to this frequency. The consequent approach taken and the efficiency of such approach are presented in this paper. Responses to waves of a single frequency are investigated along with responses obtained from wave spectra characterising typical sea states. The extent of control is quantified using peak and root mean squared dynamic responses respectively. The tests present some guidelines and challenges for testing scaled devices in relation to including response control mechanisms. Additionally, the results provide a basis for dictating future research on tuned liquid column damper based control on floating platforms.

http://iopscience.iop.org/article/10.1088/1742-6596/628/1/012058/pdf

Performance of a Single Liquid Column Damper for the Control of Dynamic Responses of a Tension Leg Platform

Energy harvesting from structural vibration using piezoelectric material has received much attention in the past few years. The idea is to scavenge energy out of a vibrating host. Coupling energy harvesting with structural vibration control is a challenging task due to conflicting goals. But dynamic vibration absorbers (DVA) used to reduce vibrations in the primary structure has potential for energy harvesting capability. In this mechanism the host structure vibration is reduced by suitably shifting the motion to DVA. Vibration energy in DVA can be harvested. The harvested energy can be used to power low-powered wireless sensor systems. This paper analyses the prospect of using vibration absorbers for possible energy harvesting under random excitation. To achieve this goal, vibration absorber is supplemented with a piezoelectric stack for both vibration confinement and energy harvesting. The primary goal is to control the vibration of the host structure and the secondary goal is to harvest energy out of the dynamic vibration absorber simultaneously. It is shown that with a proper choice of harvester parameters a broadband energy harvesting can be obtained combined with vibration reduction in the primary structure. Analytical studies are carried out considering stationary Gaussian white noise excitation within the frequency band of interest. Finally a single storey building under seismic excitation is considered and numerical results of structural control and energy harvested are shown.

Shaikh Faruque Ali

Papers

Fluorinated Nanocellulose-Reinforced All-Organic Flexible Ferroelectric Nanocomposites for Energy Generation C

Energy Harvesting From Dynamic Vibration Pendulum Absorber

Performance of a Single Liquid Column Damper for the Control of Dynamic Responses of a Tension Leg Platform

Energy harvesting dynamic vibration absorber under random vibration

Uncertainty quantification of bladed disc systems using data driven stochastic reduced order models