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Dissertation
Dissertation Xu V1.pdf
(2017)
  • Jiawen Xu, University of Connecticut - Storrs
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 of the piezoelectric metamaterial.  Transverse wave is considered throughout the modeling and analysis, and the lumped parameters are derived based on the wavenumber involved.  Taking advantage of the model, we identify the influence of a key parameter, the system-level electro-mechanical coupling coefficient of the piezoelectric transducer in a unit-cell, 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.  Our research indicates that such shifting of the velocity of acoustic wave, combined with the prism-like triangle-arrangement of unit-cells, will lead to a beam steering effect in the host medium.  This metamaterial synthesis is achieved by attaching/bonding arrayed piezoelectric transducers, which are connected with tunable inductors individually, to a structural medium whereas the structure remains unchanged.  The third research task is to apply the piezoelectric metamaterials into tailoring vibration modes of finite metamaterial beam.  Here we propose that 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.  Our intention here is that by reducing the equivalent stiffness of a piezoelectric transducer, we may 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.  By choosing proper parametric combination in the piezoelectric cantilever-pendulum, we can induce internal resonance to create a new harvester.  
Keywords
  • Acoustic metamaterial,
  • piezoelectric,
  • bandgap,
  • vibration energy harvesting,
  • 1:2 internal resonance
Publication Date
Summer August 10, 2017
Degree
PhD
Field of study
Mechanical Engineering
Department
Mechanical Engineering
Advisors
Jiong Tang
Citation Information
Jiawen Xu. "Dissertation Xu V1.pdf" (2017)
Available at: http://works.bepress.com/jiawen-xu/1/