Nondestructive evaluation of the initial surface damage of structural elements by using nonlinear surface wave

非线性表面波无损评估结构构件初始表面损伤

• 批准号: 10450047
• 负责人: KAWASHIMA Koichiro
• 金额: $ 9.09万
• 依托单位: Nagoya Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10450047/
• 关键词: Ultrasonic; Nonlinear wave; Surface wave; Harmonics; Surface crack; Finite element method; Wave propagation; Semi-closed crack; 非破壊材料特性評価; 欠陥; 表面微視き裂; 位相速度分散; 波動伝播; 微視き裂; 数値シミュレーション; 損傷; 非線形波動; レーザー超音波; 材料損傷; 材料劣化; 不完全接触面

The purpose of this project is to establish an ultrasonic evaluation method of nearly closed shallow surface cracks with nonlinear surface wave. The project is composed of (a) the detection of the second harmonic of the leaky Rayleigh wave exited at nearly closed cracks with a line-focused surface wave sensor, and (b) numerical simulation of the nonlinear surface wave propagation by using FEM analysis in which contact elements are introduced to model nearly closed surface cracks.Main results obtained by this project are summarized in the followings.1) A nearly closed fatigue crack is detected by the second harmonic amplitude of the leaky Rayleigh wave of 5MHz. A line-focused PVDF sensor was used to transmit 5MHz incident wave to receive the second harmonic wave of 10MHz. The amplitude spectrum of the received waveforms identifies the second harmonic amplitude, by which the second harmonic amplitude ratio, 10MHz amplitude/5MHz amplitude, is evaluated.2) By applying weak compressive stress to close the fatigue cracks, the second harmonic amplitude ratio shows marked change. Thus, fatigue cracks are identified.3) FEM analyzes combined with contacts element to model nearly closed cracks simulate generation and propagation of the second harmonic wave excited at the cracks by the Rayleigh wave.4) The second harmonic amplitude ratio of an inclined surface cracks is far smaller than that ofa perpendicular crack.5) The second harmonic amplitude ratio is proportional to the crack depth up to a quarter of the surface wavelength, but it is saturated for deeper cracks over that depth.

本计画旨在建立一种非线性表面波之近闭合表面浅裂纹超音波评估方法。该项目包括：（a）用线聚焦表面波传感器检测近闭合裂纹处的泄漏瑞利波的二次谐波，（B）用有限元法对非线性表面波传播进行数值模拟，在有限元法中引入接触单元模拟近闭合表面裂纹。用5 MHz的泄漏瑞利波的二次谐波幅值检测到一个近闭合的疲劳裂纹。采用线聚焦PVDF传感器发射5 MHz的入射波，接收10 MHz的二次谐波。2）施加弱压应力闭合疲劳裂纹后，二次谐波幅值比发生显著变化。因此，在本发明中，3）有限元分析结合接触单元模拟近闭合裂纹，模拟了瑞利波在裂纹处激发的二次谐波的产生和传播; 4）倾斜表面裂纹的二次谐波幅值比远小于垂直裂纹; 5）疲劳裂纹的二次谐波幅值比远小于垂直裂纹二次谐波振幅比与裂纹深度成比例，直到表面波长的四分之一，但是对于超过该深度的更深的裂纹，它是饱和的。

项目成果

R. Omote, T. Ito, K. Kawashima: "FEM simulation for detecting higher harmonics excited at semi-closed surface cracks (in Japanese)"Technical reports on ultrasonic testing #21659 Japanese Society for Nondestructive Inspection. 71-74. (2001)

R. Omote、T. Ito、K. Kawashima：“用于检测半封闭表面裂纹激发的高次谐波的 FEM 模拟（日语）”超声波检测技术报告

R.Omote, K.Kawshima, T.Ito: "Simulation of nonlinear Rayleigh wave propagation through minute surface cracks"Proc. 2001 IEEE Ultrasonic Symposium. (In press). (2002)

R.Omote、K.Kawshima、T.Ito：“通过微小表面裂纹传播非线性瑞利波的模拟”Proc。

表, 川嶋, 伊藤: "表面斜め表面き裂を通過するレイリー波ノ非線形性"第9回超音波による非破壊評価シンポジウム. 61-62 (2002)

Table，Kawashima，Ito：“穿过对角线表面裂纹的瑞利波的非线性”第 9 届超声波无损评估研讨会 (2002)。

J. Okada, T. Ito, K. Kawashima, N. Nishimura: "Finite element simulation of nonlinear acoustic behavior at minute cracks using singular element"Jpn. J. Appl. Phys.. 40-2. 3579-3582 (2001)

J. Okada、T. Ito、K. Kawashima、N. Nishimura：“使用奇异元对微小裂纹的非线性声学行为进行有限元模拟”Jpn。

J.Okada,T.Ito,K,Kawashima,N.Nishimura: "Finite element simulation of nonlinear acoustic behavior at minute cracks "Japanese Journal of Applied Physics. 41(in press). (2001)

J.Okada，T.Ito，K，Kawashima，N.Nishimura：“微小裂纹非线性声学行为的有限元模拟”日本应用物理学杂志。