Date of Award

3-2000

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Jeffrey Turcotte, PhD

Abstract

The applications of antiresonant frequencies to finite element (FE) model updating are few and usually limited to numerical examples. This work uses antiresonant frequencies in the model updating of an experimental structure and analyzes the physical correctness of the updated model by using it to detect damage. Antiresonant frequencies were used in the FE model updating of a six-meter aluminum truss. The model used rigid links to model welded and bolted joints. Rigid link dimensions were used as parameters in an iterative update based on eigenvalue and antiresonance sensitivities. The first update used 11 natural frequencies and 21 antiresonant frequencies from seven experimental frequency response functions (FRFs). The second update used only 11 natural frequencies. The antiresonant updated model produced a 46% better correlation to experimental FRFs than the non-antiresonant updated joint model. The antiresonant updated model was used to predict FRFs for the FTE in 112 damaged configurations. Pattern classification and curve-fit algorithms for damage detection were tested. The curve-fit method correctly identified damage 92.6% of the time compared to 76.1% for the pattern classifier. The high quality of the model was attributed to the use of rigid links that were updated using antiresonant frequencies.

AFIT Designator

AFIT-GAE-ENY-00M-08

DTIC Accession Number

ADA380294

Comments

The author's Vita page is omitted.

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