Ultrasonic Evaluation Method for Damaged Materials Using Inverse Problem Technique

利用反问题技术对受损材料进行超声评估的方法

基本信息

批准号：
03555018
负责人：
OKAMURA Hiroyuki
金额：
$ 6.21万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

1.Development of Ultrasonic probe with focusing sensorAn ultrasonic probe with focusing sensor was newly developed to improve the evaluation performance by back-scattering method for fatigue-creep damage. The probes were applied to damaged materials but no distinct improvement was observed compared with the normal probe type. It was shown that the improvement of measuring system is more important for the measuring accuracy.2.Development of Ultrasonic measuring systemAn Ultrasonic measuring system, which is composed of Work Station, pulser-receiver and digital oscilloscope, was developed. Aided by high performance of Work Station, the on-line real-time processing of the pressure load of the probe was developed using the DC solenoid. This greatly improves the measuring accuracy of ultrasonic properties.3.Development of quasi-damaged specimen for creep-fatigue damageQuasi-damaged materials with life ratio from 25% to 100% were made experimentally. The material is Cr-Mo-V Steel, which is often used as Rotor material in the electric power plant.4.Development of evaluation method for damaged matcrials using inverse problem techniqueTwo evaluation methods for damaged materials were newly developed in addition to the normal ultrasonic attenuation method. One is a noise energy method which evaluates the damage by integrating the power spectrum of back-scattering wave and normalizing it. The other is a weighted noise energy method which also utilize integral of the spectrum but calculated under the weighted function.5.ResultIt was shown that the proposed weighted noise energy method has great advantage that the damage evaluation is not affected by the integral range of frequency. Moreover, the proposed noise energy method was found to have superior properties for the evaluation of damaged material compared with the normal ultrasonic attenuation method.

1.带聚焦传感器的超声波探头的开发新开发了带聚焦传感器的超声波探头，以提高后向散射法对疲劳蠕变损伤的评估性能。将探针应用于受损材料，但与正常探针类型相比，没有观察到明显的改善。表明测量系统的改进对于测量精度更为重要。2.超声波测量系统的开发研制了由工作站、脉冲接收器和数字示波器组成的超声波测量系统。借助工作站的高性能，利用直流电磁阀开发了探头压力负载的在线实时处理。这大大提高了超声性能的测量精度。3.蠕变疲劳损伤准损伤试件的研制实验制作了寿命比为25%~100%的准损伤材料。材料为Cr-Mo-V钢，是发电厂常用的转子材料。4.利用反问题技术开发损伤材料评估方法除常规超声波外，还新开发了两种材料损伤评估方法衰减法。一是噪声能量法，通过对后向散射波的功率谱进行积分并归一化来评估损伤。另一种是加权噪声能量法，也是利用频谱积分，但在加权函数下计算。 5 结果表明，所提出的加权噪声能量法具有损伤评估不受频率积分范围影响的优点。。此外，与普通超声波衰减方法相比，所提出的噪声能量方法在评估受损材料方面具有优越的性能。