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Analysis of Critically Refracted Lon...

Pei, Ning.

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Analysis of Critically Refracted Longitudinal and Lamb Waves for Stress Characterization.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Analysis of Critically Refracted Longitudinal and Lamb Waves for Stress Characterization./
Author:	Pei, Ning.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2017,
Description:	160 p.
Notes:	Source: Dissertation Abstracts International, Volume: 79-07(E), Section: B.
Contained By:	Dissertation Abstracts International79-07B(E).
Subject:	Acoustics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10287701
ISBN:	9780355653168

Analysis of Critically Refracted Longitudinal and Lamb Waves for Stress Characterization.
Pei, Ning.

Analysis of Critically Refracted Longitudinal and Lamb Waves for Stress Characterization. - Ann Arbor : ProQuest Dissertations & Theses, 2017 - 160 p.

Source: Dissertation Abstracts International, Volume: 79-07(E), Section: B.

Thesis (Ph.D.)--Iowa State University, 2017.

The global production of metal, in particular, steel and aluminum keeps increasing. This material is used with various fabrication processes, such as, welding, forging, and rolling that can induce stresses in the material that can subsequently impact product performance and cause phenomena such as cracking and corrosion. When investigating plate materials it is necessary to map both texture and stress under a range of loading conditions. To address these needs a wide range of both destructive and nondestructive tools have been used. One family of methods are those based on ultrasonic measurements that relate ultrasonic velocity to properties, in particular stress. Two particular challenges are faced which are the relative insensitivity of compression and shear waves to stress and that there are also other factors which can also change velocity and these are temperature, texture and grain size.

ISBN: 9780355653168Subjects--Topical Terms:

879105
Acoustics.

Analysis of Critically Refracted Longitudinal and Lamb Waves for Stress Characterization.
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100 1 $a Pei, Ning. $3 3427672
245 1 0 $a Analysis of Critically Refracted Longitudinal and Lamb Waves for Stress Characterization.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2017
300 $a 160 p.
500 $a Source: Dissertation Abstracts International, Volume: 79-07(E), Section: B.
500 $a Adviser: Leonard J. Bond.
502 $a Thesis (Ph.D.)--Iowa State University, 2017.
520 $a The global production of metal, in particular, steel and aluminum keeps increasing. This material is used with various fabrication processes, such as, welding, forging, and rolling that can induce stresses in the material that can subsequently impact product performance and cause phenomena such as cracking and corrosion. When investigating plate materials it is necessary to map both texture and stress under a range of loading conditions. To address these needs a wide range of both destructive and nondestructive tools have been used. One family of methods are those based on ultrasonic measurements that relate ultrasonic velocity to properties, in particular stress. Two particular challenges are faced which are the relative insensitivity of compression and shear waves to stress and that there are also other factors which can also change velocity and these are temperature, texture and grain size.
520 $a This project focused on an analysis of ultrasonic velocity measurements and specifically ways to improve performance and capabilities for stress characterization. Two approaches were considered and are reported: the critically refracted ultrasonic longitudinal (LCR) wave and higher order Lamb waves.
520 $a The LCR wave method was modelled and optimized based on the fact that the sensitivity between waves and stress can reach maximum when they propagate in the same direction. However, in reality this wave typically propagates at an angle to stress, which will decrease its sensitivity. This thesis reports a numerical model used to investigate the transducers parameters that can influence the directivity of the LCR wave and hence enable performance optimization when used for industrial applications. An orthogonal test method is used to study the transducer parameters which influence the LCR wave beams and this method provides a design tool that can be used to study and optimize multiple parameter experiments and identify which parameter or parameters are of most significance. The example considered simulation of the acoustic field in a 2-D water-steel model is obtained using a Spatial Fourier Analysis method. The significance of the effects of incident angle, the aperture and the center frequency of the transducer were studied. Results show that the aperture, the center frequency and the incident angle are the most important factors in controlling the directivity of the resulting LCR wave fields.
590 $a School code: 0097.
650 4 $a Acoustics. $3 879105
650 4 $a Materials science. $3 543314
650 4 $a Mechanical engineering. $3 649730
690 $a 0986
690 $a 0794
690 $a 0548
710 2 $a Iowa State University. $b Aerospace Engineering. $3 1023643
773 0 $t Dissertation Abstracts International $g 79-07B(E).
790 $a 0097
791 $a Ph.D.
792 $a 2017
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10287701