Evaluation of fatigue damage in bolted structures using nonlinearities of lamb waves

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Evaluation of fatigue damage in bolted structures using nonlinearities of lamb waves

 

Author: Wang, Binghan
Title: Evaluation of fatigue damage in bolted structures using nonlinearities of lamb waves
Degree: M.Sc.
Year: 2014
Subject: Steel, Structural -- Testing.
Bolts and nuts -- Testing.
Lamb waves.
Hong Kong Polytechnic University -- Dissertations
Department: Faculty of Engineering
Pages: xi, 72 leaves : ill. (some col.) ; 30 cm.
InnoPac Record: http://library.polyu.edu.hk/record=b2748963
URI: http://theses.lib.polyu.edu.hk/handle/200/7500
Abstract: Steel bolted connections are widely used in various industrial sectors. Different loading conditions of the connections can result in stress concentration at fasten holes, which may lead to the deterioration of fatigue damages, such phenomenon makes it significant to detect the damage nearby the bolts. Linear ultrasonic methods are currently the main methods in Non-Destructive ultrasonic detection but they may lose their effectiveness to the detection of fatigue damage. On the other hand, the nonlinear guided waves are sensitive to small-scale damage. In this project, the principle of nonlinear lamb waves for detection of fatigue damage was introduced first, which was used to detect the presence of the small-scale fatigue damage. Two rows of transducers were used to generate and detect the fundamental and second harmonic Lamb waves. A probability-based imaging algorithm was further presented and used to locate the fatigue damage. The approach was verified experimentally by evaluating fatigue damage in aluminum plate with "W-shape" bolt holes, successfully detected and located fatigue area with good accuracy. Compared with current linear ultrasonic methods, this approach is more sensitive to small-scale fatigue damage and is independent of benchmark.

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