特殊几何构件超声衍射时差法技术有限元模拟

Finite element simulation analyses of ultrasonic time of flight diffraction technique in special geometry components

衍射时差法(Time of flight diffraction,TOFD)技术是一种能够探测和精确测量缺陷尺寸的新型超声无损检测方法,针对该检测方法具有缺陷检出率高、缺陷定位定量精度高等优点。本文采用商业有限元软件ABAQUS,对汽包筒体与球形封头不等厚对接和超高压水晶釜两种特殊几何构件进行了超声TOFD技术的二维数值模拟研究,分析了超声波在这两种构件中的传播特性和规律。经分析从构件表面不同位置接收到的波型,当构件中存在损伤时,通过接收损伤所引起的衍射波,可判断构件中是否存在缺陷。模拟结果表明能够将超声TOFD技术应用于这两种特殊结构的压力容器构件,可扩大超声TOFD技术的应用范围。

The time-of-flight diffraction（ TOFD） technique is a new ultrasonic nondestructive testing method used for the detection and sizing of defects accurately. This method can be applied to detect flaw effectively with high precision of localization and quantification. In this paper,the application of two-dimensional numerical simulation of ultrasonic TOFD technique was carried out in the special geometry components,unequal thickness butt weld of drum shell and spherical head and ultra high pressure crystal kettle,using the commercial finite element software ABAQUS,the propagation characteristics and laws of ultrasonic wave in such two components are analyzed. The waves that received on different position of components surface wereexplained. When there is a discontinuity in components,the defect can be confirmed by the analysis of diffracted waves that caused by defect. The simulation results show that ultrasonic TOFD technique can be used in such two pressure vessel components of special structure,so the application scope of ultrasonic TOFD technique will be expanded.