Subharmonic ultrasonic measurement and imaging for quantitative evaluation of stress corrosion and fatigue cracks

用于定量评估应力腐蚀和疲劳裂纹的次谐波超声测量和成像

基本信息

批准号：
16206071
负责人：
YAMANAKA Kazushi
金额：
$ 31.28万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

To establish the basis of subharmonic ultrasonic measurement and imaging of the fatigue and stress corrosion cracks, we first derived an analytical solution considering the adhesion force, and realized the relation between the threshold of subharmonic eave generation and the crack closure stress. Nest, we developed the elastc body-oscillator model since detailed information is needed to develop practical apparatus. Through numerical analysis of this model, we investigated the dependence of subharmonic wave upon the input wave amplitude and upon the closure stress, and comparison between measured and calculated waveform in experiments of fatigue cracks in an aluminum alloy (A7075).As the next step we developed nonlinear ultrasonic imaging system for detailed measurement of the depth of closed cracks in thickness direction. As a transmitter, we employed a LiNbO3 single crystal oscillator that has excellent durability for high voltage electric signal and employed an array sensor for producing image by the received signal focusing. Moreover, the delay law within the specimen was formulated and designed a IIR digital filter as a preprocess before imaging to construct a system that can be used to obtain linear and nonlinear images of cracks.In addition, we applied the developed system above described to open and closed cracks in aluminum alloy and showed that the subharmonic image is useful for imaging closed cracks. Moreover, we verified the system to closed crack in stainless steel (SUS316L) specimen with comparable thickness to that used in recirculator piping of atomic power plants. Then we proved that it has high accuracy in crack sizing. Finally, we applied this system to cracks in steel specimen generated under processing, and we showed that the system is useful for oblique and branched cracks.

为了建立亚谐波超声测量的基础和疲劳和应力腐蚀裂纹的成像，我们首先得出了一个分析溶液，考虑了粘附力，并意识到了亚谐波河口产生的阈值与裂纹闭合应力之间的关系。 Nest，我们开发了ElastC身体振荡器模型，因为需要详细的信息来开发实际的设备。通过对该模型的数值分析，我们研究了亚谐波波对输入波振幅和闭合应力的依赖性，并在铝合金中的疲劳裂纹实验中测量和计算的波形之间的比较（A7075）（A7075）。由于下一步，我们开发了非线性超音素成像系统，以详细的尺寸裂纹，厚度为厚度的裂纹，并在厚度裂纹。作为发射器，我们采用了LINBO3单晶振荡器，该振荡器具有出色的高压电信号耐用性，并采用了阵列传感器来通过接收的信号聚焦来产生图像。此外，在成像之前制定了标本内的延迟定律，并设计了IIR数字过滤器作为预处理，以构建一个可用于获得裂纹的线性和非线性图像的系统。此外，我们在铝合金中应用了上述开发的系统，并显示了铝合金中的打开和封闭的裂纹，并表明Subharmonic Image对封闭成像裂纹有用。此外，我们验证了该系统的不锈钢（SUS316L）样品的闭合裂纹，其厚度与原子发电厂的循环管道中所用的厚度可比。然后，我们证明了它在裂纹尺寸方面具有很高的精度。最后，我们将该系统应用于处理下生成的钢试样的裂纹，并表明该系统对倾斜和分支裂纹有用。