Title page for ETD etd-06012006-140648


Type of Document Dissertation
Author Peairs, Daniel Marsden
Author's Email Address dpeairs@vt.edu
URN etd-06012006-140648
Title High Frequency Modeling and Experimental Analysis for Implementation of Impedance-based Structural Health Monitoring
Degree PhD
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Inman, Daniel J. Committee Chair
Leo, Donald J. Committee Member
Park, Gyuhae Committee Member
Robertshaw, Harry H. Committee Member
Singh, Mahendra P. Committee Member
Keywords
  • spectral elements
  • sensor resonance
  • multiplexing
  • high frequency vibration
  • impedance method
  • structural health monitoring
  • damage metric
Date of Defense 2006-05-19
Availability unrestricted
Abstract
A promising structural health monitoring (SHM) method for implementation on real world structures is impedance-based health monitoring. An in-service system is envisioned to include on board processing and perhaps wireless transfer of data. Ideally, a system could be produced as a slap-on or automatically installed addition to a structure. The research presented in this dissertation addresses issues that will help make such a system a reality. Although impedance-based SHM does not typically use an analytical model for basic damage identification, a model is necessary for more advanced features of SHM, such as damage prognosis, and to evaluate system parameters when installing on various structures. A model was developed based on circuit analysis of the previously proposed low-cost circuit for impedance-based SHM in combination with spectral elements. When a three-layer spectral element representing a piezoceramic bonded to a base beam is used, the model can predict the large peaks in the impedance response due to resonances of the bonded active sensor. Parallel and series connections of distributed sensor systems are investigated both experimentally and with the developed model. Additionally, the distribution of baseline damage metrics is determined to assess how the large quantities of data produced by a monitoring system can be handled statistically. A modification of the RMSD damage metric has also been proposed that is essentially the squared sum of the Z-statistic for each frequency point. Preferred excitation frequencies for macro-fiber composite (MFC) active sensors are statistically determined for a long composite boom under development for use in rigidizable inflatable space structures.
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