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Crack evaluation in a simple structure using a vibration technique

Bui, Henry (2016). Crack evaluation in a simple structure using a vibration technique. Bachelor of Engineering (4th Year Project) Thesis, Charles Darwin University.

Document type: Thesis
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Author Bui, Henry
Title Crack evaluation in a simple structure using a vibration technique
Institution Charles Darwin University
Publication Date 2016
Thesis Type Bachelor of Engineering (4th Year Project)
Supervisor Lilley, David M.
Fairfield, Charlie A.
0905 - Civil Engineering
Abstract A beam structure subjected to different loading conditions is likely to have localised stress concentrations when loaded. High magnitudes of stress and repeated loading may lead to the development of cracks. Given the wide use of steel beams, the presence of cracks is a source of serious concern as cracks decrease the structural integrity of the structure. This can have catastrophic consequences in terms of human life, property damage, and economic losses. In order to eliminate or reduce the chances of structural failure due to a crack, it is desirable that any crack is detected in its early stages of development, before it becomes structurally significant.

The purpose of this thesis is to evaluate a crack on a simple structure using a vibration technique. This investigation presents a method of non-destructively assessing a structure to detect a crack from vibration measurements taken at a single point on the structure.

Finite element analysis (FEA) software was used to model and understand the effects of crack severity and varying crack position along the length of the beam. This analysis determined how these crack characteristics affect the resonant frequencies of the structure’s mode of vibration.

An impact test was used to obtain vibration measurements for a non-cracked and cracked beam. A saw-cut of various percentage reductions in cross-sectional area was used to resemble the crack. The data obtained were used in conjunction with receptance methods to indicate the location of the crack.

Experimental results were performed on a universal beam (150UB14.0 Grade 300).
Keyword resonant frequency
evaluation crack
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Created: Wed, 30 Aug 2017, 10:26:12 CST by Jessie Ng