Study of Ultrasonic Phased Array in Underwater Welding

Abstract

The popular sensors used in water have a lot of difficulties when compared with those used in land welding automation. It is meaningful to find a new kind of sensor which is suitable to work in underwater welding. Ultrasonic phased array (PA) can work in water conveniently and send out required sound beam. Compared with single-ultrasonic sensor, PA works faster and effectively. In this chapter, interference principle of acoustic beam is analyzed first. Then, the relationship of focusing precision, PA shape, gap distance between adjacent units, sensor element number, and time resolution is revealed with simulation. Proper physical parameters of PA are determined. At last, high time resolution circuit based on complex programmable logic device (CPLD) is given out. It works together with sound-emitting and -receiving circuits to realize fast scan on welding workpiece, so that the seam line can be deduced with underwater distance detection.