Numerical study for Global Detection of cracks embedded in beams
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Authors
Lipsey, Stephen A.
Subjects
Advisors
Kwon, Young W.
Date of Issue
1999-12
Date
December, 1999
Publisher
Monterey, California: Naval Postgraduate School
Language
en_US
Abstract
Damage reduces the flexural stiffness of a structure, thereby altering its dynamic response. Considerable effort has been put into obtaining a correlation between the changes in modal parameters and the location and amount of the damage within the structure. Most numerical research employed elements with reduced beam stiffiness to simulate damage in the beam. This approach to damage simulation neglects the non-linear effect that a crack has on the structural dynamic response. In the present study, finite element modeling techniques are utilized to directly represent an embedded crack. The results of the dynamic analysis of the present model are then compared to the results of the dynamic analysis of the reduced modulus finite element model. Different modal parameters are investigated to determine the most sensitive indicator of damage and fts location. Nonlinear effects, such as crack closure and opening, of an embedded crack on the structural dynamic response were also studied from transient nonlinear analysis. The modeling technique is then applied to sandwich composite beams with simulated delamination to investigate damage detection techniques through the use of damping caused by frictional dissipation of energy on the crack surface.
Type
Thesis
Description
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NPS Report Number
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Format
xii, 51 p.;28 cm.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.