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Development of automatic measuring system of ultrasonic attenuation using spectrum analysis

频谱分析超声衰减自动测量系统的研制

基本信息

批准号：
63850022
负责人：
OKAMURA Hiroyuki
金额：
$ 5.38万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-63850022/
关键词：
Ultrasonic Attenuation Ultrasonic Testing Non Destructive Testing Fatigue Creep Estimation of Remaining Life Spectrum Analysis Automatic Measuring System 超音波測定クリープ

项目摘要

The life extension of high temperature plants is strongly expected recently, so that the accurate remaining life assessment of them has come to be an important problem. This report presents a new non-destructive evaluation technique using ultrasonic waves for the evaluation of aging deterioration damage ( caused by creep and high temperature fatigue ) of high temperature components. In previous works, ultrasonic attenuation is evaluated from the 1st and 2nd peak values of pulse-echo ultrasonic wave. However the attenuation values evaluated by this method may have some error, because those values are greatly affected by the super-imposed noise. In the present work, two new algorithms for the improvement of measuring accuracy of ultrasonic attenuation using spectrum analysis has been developed. One is the method that evaluates the attenuation values from envelope curve of original ultrasonic waves, the other is that evaluates the attenuation values by calculating the system function of specimen from the 1st and 2nd echoes. Several ultrasonic waves obtained from Monte Carlo simulation and degraded specimen are analyzed by using, both the proposed methods and the conventional method. It is shown through the comparison that the proposed methods enable us to measure ultrasonic attenuation more accurately than before, and that the attenuation values tend to increase as decreasing of the remaining life. It is also clarified that the attenuation values is effective as non- destructive evaluation parameter of creep and high temperature fatigue. The developed algorithms are installed on the measuring system which consists of a personal computer, ultrasonic apparatus, and digital storage oscilloscope. In addition the analysis time is very much shortened by incorporating FFT-analyzer in this system. Finally, all of procedures of instrumentation and analysis can be automated fully, and it will enable us to apply the above ultrasonic method to real structures.

近年来，人们强烈期望高温植物的寿命延长，因此对其进行准确的剩余寿命评估已成为一个重要的问题。提出了一种利用超声波对高温构件时效劣化损伤(蠕变和高温疲劳)进行无损检测的新技术。在以前的工作中，超声衰减是根据脉冲回波超声波的第一和第二峰值来评估的。但是，由于叠加噪声对衰减值的影响较大，因此该方法估计的衰减值可能会有一定的误差。本文提出了两种利用频谱分析提高超声衰减测量精度的新算法。一种是从原始超声波包络曲线估计衰减值的方法，另一种是根据第一次和第二次回波计算试件的系统函数来估计衰减值的方法。用所提出的方法和常规方法对蒙特卡罗模拟和退化试件得到的几种超声波进行了分析。结果表明，所提出的方法能更准确地测量超声衰减，且衰减值随剩余寿命的减小而增大。并说明衰减值作为蠕变和高温疲劳的无损评价参数是有效的。所开发的算法被安装在由个人计算机、超声仪和数字存储示波器组成的测量系统上。此外，通过在该系统中加入FFT分析仪，大大缩短了分析时间。最后，仪器和分析的所有过程都可以完全自动化，这将使我们能够将上述超声方法应用于实际结构。