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Passively-Switched Vibrational Energ...

Liu, Tian.

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Passively-Switched Vibrational Energy Harvesters.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Passively-Switched Vibrational Energy Harvesters./
Author:	Liu, Tian.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2017,
Description:	172 p.
Notes:	Source: Dissertation Abstracts International, Volume: 78-10(E), Section: B.
Contained By:	Dissertation Abstracts International78-10B(E).
Subject:	Mechanical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10276237
ISBN:	9781369806632

Passively-Switched Vibrational Energy Harvesters.
Liu, Tian.

Passively-Switched Vibrational Energy Harvesters. - Ann Arbor : ProQuest Dissertations & Theses, 2017 - 172 p.

Source: Dissertation Abstracts International, Volume: 78-10(E), Section: B.

Thesis (Ph.D.)--Northeastern University, 2017.

Vibrational energy harvesters capture mechanical energy from ambient vibrations and convert the mechanical energy into electrical energy to power wireless electronic systems. Challenges exist in the process of capturing mechanical energy from ambient vibrations. For example, resonant harvesters may be used to improve power output near their resonance, but their narrow bandwidth makes them less suitable for applications with varying vibrational frequencies. Higher operating frequencies can increase harvesters' power output, but many vibrational sources are characterized by lower frequencies, such as human motions. This work presents the design, modeling, optimization, and demonstration of a new class of resonant vibrational energy harvesters that passively switch among dynamics with different characteristic frequencies to adapt to low-frequency excitations and changing vibrational environment. The passively-switched harvester consists of a driving beam that couples into ambient vibrations at low frequencies and a generating beam that converts mechanical energy into electrical energy at high frequencies. The interaction between the driving beam and the generating beam enables multiple characteristic dynamics of the system, namely coupled-motion dynamics and plucked dynamics. When the system passively switches between coupled-motion harvesting and plucked harvesting, its operational range is increased. The system is simulated in the time domain using a lumped element model that predicts power output. Based on the model, a passively-switched harvester in which the driving beam faces the generating beam is designed and experimentally tested over an operational range of 0.1g-2.6g and 4 Hz-27 Hz. The experimental results agree with the simulation that the harvester has increased operational range due to the system's ability of passive switching among multiple dynamics. To create a more compact system, a second passively-switched harvester is created in which the beams are nested together. The nested-beam configuration achieves a 6X smaller device volume while retaining a similar system resonance. The nested-beam harvesters are experimentally tested within an operational range of 0.1g-2g and 5 Hz-22Hz, generating greater than 20 muW over a frequency range of 5.5 Hz-11 Hz at 0.8g. The nested-beam harvester retains a similar normalized power density of 148 muW/cm3g2 at 0.5g and 7Hz as compared with the facing-beam harvester.

ISBN: 9781369806632Subjects--Topical Terms:

649730
Mechanical engineering.

Passively-Switched Vibrational Energy Harvesters.
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520 $a Vibrational energy harvesters capture mechanical energy from ambient vibrations and convert the mechanical energy into electrical energy to power wireless electronic systems. Challenges exist in the process of capturing mechanical energy from ambient vibrations. For example, resonant harvesters may be used to improve power output near their resonance, but their narrow bandwidth makes them less suitable for applications with varying vibrational frequencies. Higher operating frequencies can increase harvesters' power output, but many vibrational sources are characterized by lower frequencies, such as human motions. This work presents the design, modeling, optimization, and demonstration of a new class of resonant vibrational energy harvesters that passively switch among dynamics with different characteristic frequencies to adapt to low-frequency excitations and changing vibrational environment. The passively-switched harvester consists of a driving beam that couples into ambient vibrations at low frequencies and a generating beam that converts mechanical energy into electrical energy at high frequencies. The interaction between the driving beam and the generating beam enables multiple characteristic dynamics of the system, namely coupled-motion dynamics and plucked dynamics. When the system passively switches between coupled-motion harvesting and plucked harvesting, its operational range is increased. The system is simulated in the time domain using a lumped element model that predicts power output. Based on the model, a passively-switched harvester in which the driving beam faces the generating beam is designed and experimentally tested over an operational range of 0.1g-2.6g and 4 Hz-27 Hz. The experimental results agree with the simulation that the harvester has increased operational range due to the system's ability of passive switching among multiple dynamics. To create a more compact system, a second passively-switched harvester is created in which the beams are nested together. The nested-beam configuration achieves a 6X smaller device volume while retaining a similar system resonance. The nested-beam harvesters are experimentally tested within an operational range of 0.1g-2g and 5 Hz-22Hz, generating greater than 20 muW over a frequency range of 5.5 Hz-11 Hz at 0.8g. The nested-beam harvester retains a similar normalized power density of 148 muW/cm3g2 at 0.5g and 7Hz as compared with the facing-beam harvester.
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