Accurate Sizing of Closed Crack Using Nonlinear Ultrasound of SPACE with High Voltage Transformer Pulser Technique

As the improvement of the detectability of crack tip echo in ultrasonic inspection with low S/N ratio, we developed SPACE (Subharmonic Phased Array Crack Evaluation) as a subharmonic ultrasound imaging technique. Although the pulser of conventional SPACE could incident large displacement ultrasound to a crack, availability of the SPACE measurement was limited for only closed crack. In order to use the SPACE system for wider industrial inspection fields, we have been developed the larger displacement ultrasound incidence equipment considering the crack opening supposed to be several nm to sub- mu m in order. In this study, we developed new SPACE combining high voltage transformer to a low cost pulser. The availability of the developed system in ultrasonic inspection was investigated using several model cracks.