• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Experimental study of the time domain damage identification

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_td_3108965_sip1_m.pdf
    Size:
    2.884Mb
    Format:
    PDF
    Download
    Author
    Vo, Peter Hoa
    Issue Date
    2003
    Keywords
    Engineering, Civil.
    Engineering, Mechanical.
    Advisor
    Haldar, Achintya
    
    Metadata
    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    A theoretical and experimental study was undertaken to validate the use of a novel time-domain system identification (SI) method for detecting changes in stiffnesses of uniform cross section fixed-fixed and simply supported beams. By quantifying the reduction of beam's elemental stiffnesses, the location of damage can be detected. The Iterative Least Squares (ILS-UI) algorithm, a novel, time-domain SI algorithm, being developed at the University of Arizona for nondestructive evaluation of structures, is used for this purpose. The ILS-UI algorithm requires the use of nodal response time histories to develop an equivalent multi-degree-of-freedom model in which the number of node points is equal to the number of sensors used in the experiment. To optimize the number of sensors, a finite element model was developed in which the beam was discretized into an optimum number of node points, such that nodal responses at these node points are equivalent to that of the continuous beam. As a prelude to the experimental validation, a simulation was performed to study errors in the numerical integration of a digitized signal for three different rules: trapezoidal, Simpson's and Boole's. It was shown that Simpson's rule and Boole's rule yield smaller errors than the trapezoidal rule, especially when lower sampling rates are used. Several post processing techniques to remove noise, to filter out high frequencies and remove slope and offset from a data set were also demonstrated. In the first phase of the validation experiments, the optimum number of node points was determined for the fixed beam. Also, a method was developed to scale angular response based on the measured transverse response. The ILS-UI algorithm was then used to predict element stiffnesses for the fixed beam. The stiffness predictions did not converge. This prompted an investigation to determine the root cause of the failure. It was found that amplitude and phase errors in the accelerometer's measurements were the root cause of the failure. After this was determined, an alternative approach was developed to mitigate the amplitude and phase shift errors. To validate the alternative approach, nodal responses were measured for the beam with and without damage. The ILS-UI algorithm was demonstrated to successfully quantify reduction in the beam's element stiffnesses and the location of damage was identified.
    Type
    text
    Dissertation-Reproduction (electronic)
    Degree Name
    Ph.D.
    Degree Level
    doctoral
    Degree Program
    Graduate College
    Civil Engineering and Engineering Mechanics
    Degree Grantor
    University of Arizona
    Collections
    Dissertations

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.