A possible mechanism causing subharmonics in ultrasonic testing of a closedcrack

Keiichi Naito, Toshihiko Sugiura

研究成果: Conference contribution

5 被引用数 (Scopus)

抄録

Nowadays nondestructive testing is noted due to the need of maintenance instructures, such as nuclear energy plants and aircrafts. However, detection andsizing of a closed crack are difficult by the conventional ultrasonic testing,because ultrasonic waves penetrate the contact area of the closed crack. Nownonlinear ultrasonic testing is attracting attention. Though there have beenexperimental reports on superharmonics or subharmonics and some theoreticalresearches accounting the superharmonics, so far there have yet been few reportsthat clarify the mechanism causing the subharmonics. Generation ofsuperharmonics at a closed crack was theoretically explained by modeling thecontact of the crack surfaces as a nonlinear spring. This modeling is based onthe fact that, when the gap between the crack surfaces decreases, the contactpressure increases nonlinearly due to the asperity of the crack surfaces. Inthis study a closed crack was regarded as a nonlinear spring with up to thethird order terms, and nonlinear analysis and numerical simulation were carriedout. In experiment, two aluminum specimens strongly pressed were used in placeof a metal block with a closed crack. Numerical simulation predicts generationof the subharmonics. They can appear if the input frequency close to twice thenatural frequency. Conditions for the subharmonics can also be foundanalytically with respect to the input frequency and the input amplitude.Subharmonics were also confirmed by experiment. In conclusion, a possiblemechanism causing the subharmonics at a closed crack was explained by regardinga closed crack as a nonlinear spring with up to the third order terms.

本文言語English
ホスト出版物のタイトル2010 IEEE International Ultrasonics Symposium, IUS 2010
ページ2392-2395
ページ数4
DOI
出版ステータスPublished - 2010 12 1
イベント2010 IEEE International Ultrasonics Symposium, IUS 2010 - San Diego, CA, United States
継続期間: 2010 10 112010 10 14

出版物シリーズ

名前Proceedings - IEEE Ultrasonics Symposium
ISSN(印刷版)1051-0117

Other

Other2010 IEEE International Ultrasonics Symposium, IUS 2010
国/地域United States
CitySan Diego, CA
Period10/10/1110/10/14

ASJC Scopus subject areas

  • 音響学および超音波学

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