Study Of Data Acquisition And Processing On Phased-array Ultrasonic For Circumferential Weld

Nowadays,ultrasonic non-destructive testing method has already been widely used and rapidly developed. Ultrasonic testing method has many advandages, such as various testing objects, large testing depth, accurate flaw orientation and low cost. With the development of computer technology, ultrasonic testing instrument becomes more and more automatic. The range of testing objects becomes more and more wide , sampling rate becomes more and more rapid and flaw orientation becomes more and more accurate. Based on ultrasonic pulse echo theory and phased array technology, this article introduces a multichannel ultrasonic testing system used for welded seam.The following are main achievements of this thesis:1. Both data processing structure and software are designed to accomplish phased array ultrasonic for circumferential welded. The multichannel ultrasonic testing card is redesighed in order to improve the quality. Through simplifying the system, we can heighten the precision of delay. The design method based on FPGA improved the system's sampling rate and processing ability greatly. The delay and sampling circuit can work at any delay time. For this system, the precision of delay can be up to 2.5ns while its sampling rate is only 100MHz, we can achieve it with ADC of 100MHz sampling rate.2. The FPGA in the multichannel ultrasonic testing card is designed and emulated.3. The channel's sensitivity of ultrasonic testing system is designed to adjust automatically. The MCU of testing card achieves auto control of every channel's sensitivity through gain amplification circuit. Thereupon we can discover the flow given size in workpiece and batch it.4. USB hardware and software interface is designed to allow high speed data transmission between testing card and PC.