Ultrasonic Evaluation Method for Damaged Materials Using Inverse Problem Technique

1.带聚焦传感器的超声探头的研制为提高后向散射法评价疲劳蠕变损伤的性能，研制了带聚焦传感器的超声探头。将探头应用于受损材料，但与正常探头类型相比没有明显改善。2.超声测量系统的研制研制了一种由工作站、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，利用直流电磁铁实现了探头压力载荷的在线实时处理。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。4.基于反问题技术的材料损伤评估方法的研究除常规的超声衰减法外，还发展了两种新的材料损伤评估方法。一种是噪声能量法，它通过积分后向散射波的功率谱并对其进行归一化来评估损伤。另一种是加权噪声能量法，它也是利用谱的积分，但在加权函数下计算。5.结果表明，加权噪声能量法具有不受频率积分范围影响的优点。此外，与常规的超声衰减法相比，提出的噪声能量法对损伤材料的评价具有更好的性能。

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.