Development of Sound Pressure Field Evaluation system for NDE Ultrasonic Transducer Using Photoelastic CT Method

由于超声检测在很大程度上依赖于超声换能器，因此必须对所使用的每个超声换能器的声压场进行详细研究。最合适的测量系统是光弹性超声可视化系统。然而，这些方法只能测量二维声压场，对于标准的换能器评价系统来说是不够的。本研究采用光弹性计算机断层扫描（CT）方法对纵波声压分布进行三维测量。在法向证明产生的声压分布的近场中，观察到一个显示三维声压分布的干涉图样。观察了频率和传播距离对三维声压分布的影响，并与波动理论进行了比较。利用该系统还观察了线聚焦光束换能器的近场声压分布。

Since ultrasonic inspection depend strongly on ultrasonic transducer, detail of the sound pressure field of each ultrasonic transducer used must be investigated. Most suitable measurement system was ultrasonic visualization system using photo elasticity. However, these method can only measure two dimensional sound pressure field which is not enough for standard transducer evaluation system.In this research, photoelastic computer tomography (CT) method was developed for three dimensional measurement of sound pressure distribution of a longitudinal wave.In a near field of the sound pressure distribution produced by the normal prove, an interference pattern which shows the three dimensional sound pressure distribution was observed. The effects of frequency and propergation distance on the three dimensional sound pressure distribution were observed and compared with wave theory.Near field of the sound pressure distribution of line focus beam transducer were also observed using this system.