Damage inspection of isotropic/multi-layer plates by time-frequency analysis of lamb waves

Resource Information

The work Damage inspection of isotropic/multi-layer plates by time-frequency analysis of lamb waves represents a distinct intellectual or artistic creation found in University of Missouri Libraries. This resource is a combination of several types including: Work, Language Material, Books.

Label

Damage inspection of isotropic/multi-layer plates by time-frequency analysis of lamb waves

Statement of responsibility

by Haoguang Deng

Creator

• Deng, Haoguang, 1989-

Contributor

• Pai, P. Frank, (Perngjin Frank)

Author

• Deng, Haoguang, 1989-

Thesis advisor

• Pai, P. Frank, (Perngjin Frank)

Subject

• Frequencies of oscillating systems
• Lamb waves
• Materials -- Evaluation
• Thin-walled structures -- Inspection
• Academic theses
• Dissertations, Academic -- University of Missouri--Columbia -- Mechanical & aerospace engineering

Genre

• Academic theses

Language

eng

Summary

Wave-based technique is one major approach for damage inspection of structures. To detect a small damage, an elastic wave's wavelength often needs to be as small as the damage size and hence the frequency needs to be high. Unfortunately, high-frequency wave dynamics always involves complicated wave reflection, refraction and diffraction, and it is difficult to separate them in order to have detailed examination and system identification. This research work investigates dynamic characteristics of Lamb waves in plates that can be used for material evaluation and damage inspection of thin-walled structures. A one-dimensional finite-element modeling and analysis technique is developed for computing dispersion curves and all symmetric and anti-symmetric modes of Lamb waves in isotropic and multi-layer plates. Moreover, a conjugate-pair decomposition (CPD) method is introduced for time-frequency analysis of propagating Lamb waves. Results show that, under a k-cycle sine-burst excitation at a plate's edge, the time-varying frequency of a surface point's response can reveal the Lamb wave propagating inside the plate being a symmetric or anti-symmetric mode. The frequency of the measured wave packet increases from the wave front to the trailing edge if it is a symmetric mode, and the frequency decreases from the wave front to the trailing edge if it is an anti-symmetric mode. Moreover, interaction of two different waves results in a peak in the time-frequency curve. These characteristics can be used for accurate wave separation and speed identification of different waves to enable fast and accurate material evaluation and damage inspection. Results from transient finite-element analysis of Lamb waves propagating in finite plates with crack/delamination show that k-cycle sine-burst probing waves are good agents for wave-based damage inspection of plates. Although crack and delamination introduce different waves into and complicate the probing wave packet, time-frequency analysis makes it possible to separate such damage-induced small waves from the probing wave and enables fast and accurate damage inspection of thin-walled structures

Cataloging source

MUU

Degree

M.S.

Dissertation note

Thesis

Dissertation year

2014.

Government publication

government publication of a state province territory dependency etc

Granting institution

University of Missouri--Columbia

Illustrations

illustrations

Index

no index present

Literary form

non fiction

Nature of contents

• dictionaries
• bibliography
• theses