Date of Completion

7-30-2017

Embargo Period

2-6-2018

Keywords

Acoustic metamaterial, bandgap, piezoelectric, energy harvesting, internal resonance

Major Advisor

Jiong Tang

Co-Major Advisor

Nejat Olgac

Associate Advisor

George Lykotrafitis

Associate Advisor

Xu Chen

Associate Advisor

Ying Li

Field of Study

Mechanical Engineering

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

The objective of this dissertation research is on the designing and optimization of promising wave guiding and energy manipulation approach. Specifically address above-mentioned issues of modeling and application of piezoelectric metamaterials and energy harvesting. The first research task is to develop fundamental modeling and understanding of piezoelectric metamaterial integrated with LC shunts to create local resonances. We establish the lumped-parameter model. Taking advantage of the model, we identify the influence of a key parameter to the behavior of the metamaterial. The second research task is to explore the application of the piezoelectric metamaterials in acoustic wave guiding. This work is based on the significant acoustic wave velocity shifting in the vicinity of the bandgap. Such shifting leads to a beam steering effect in the host medium. The third research task is to apply the piezoelectric metamaterials into tailoring vibration modes. The combination of resonance and antiresonance can create unusual vibration mode in a finite metamaterial beam. The fourth research task is to enhance the energy harvesting efficiency. By reducing the equivalent stiffness of a piezoelectric transducer, we reduce the portion of elastic energy stored in the mechanical part of the system and therefore, enhance the power output efficiency. The fifth research task is to realize single cantilever based multi-directional energy harvesting. We replace the proof-mass used in simple cantilever by a pendulum. Take advantage of 1:2 internal resonance, the system is capable of transferring the input mechanical energy in different directions to the beam bending motion with high efficiency.

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