Opposite Phased Transducer — Novel Type of Transducer

摘要

Defect sizing is an important task giving input to fracture mechanics evaluation. The exact evaluation of sound field is the key factor to analyse precisely defects in materials. Sizing accuracy is affected by the size of the sound field. There are several methods available for sizing: SAFT, Acoustic Holography, Tip diffraction, Amplitude drop. In SAFT and acoustic holography applications the sound field is calculated according to the back propagation of sound waves from an object (defect, flaw). The echoes are calculated according to their origin. In tip diffraction technique the external sides of defect are determined based on direct echoes coming from the crack tips. Amplitude drop technique is affected by the sound field size to defect size ratio. Opposite phased transducer is based on sound field determination in design phase. The sound field is calculated using an ultrasonic modelling software and the sound field is very narrow also for a long sound path distance. This feature is used when sizing by using opposite phased transducer.