The Design Of The Ultrasonic Nondestructive Testing System Based On Double Probes

With the rapid development of industry, non-destructive testing technology has been widely used in many fields and attracting more and more attention, especially in aerospace, nuclear power station and other top fields. Ultrasonic testing technology has been paid more attention. According to the numbers of probes, the testing style can be divided into single probe, double probes and array type; according to the detection principle, the testing style can be divided into transmission, reflection and resonance method. This paper mainly studies the transmission with double probes.This design mainly includes the following aspects:(1) To study and understand the physical foundation and the detection principle of ultrasound, determine the designing method of transmission with the double probes. To study the working principle of ultrasonic transducer. after testing and evaluation, finally choose the ultrasonic transducer of DOBO company, its center frequency is 2.5MHz and the size is 14mm. It has nice penetration effect and resolution.(2) Completing the design of the receive and dispatch circuit. Through consulting data, calculating parameters and testing, i confirm the plan of the schematic of the receive and dispatch circuit. It contains the square wave pulse circuit, a filter circuit, the high voltage excitation circuit, a preamplifier circuit and an amplifying circuit.the receiving circuit uses the low distortion and low disturbance operational amplifiers. The testing points are placed on the PCB to test the effect of the square wave pulse circuit, the excitation pulse, the preamplifier circuit and the amplifying circuit, and record the amplitude, period, peak value and so on.(3) By comparing the two solutions, determine the design of the digital signal processing which is based on FPGA. The digital signal circuit mainly includes the analog-to-digital conversion circuit, the control circuit of FPGA and communication circuit. The resolution of the analog-to-digital conversion circuit reaches 12 bits, FPGA has the ability to process the high speed data, and guarantee the real-time transmission and the display of the data. The communication circuit uses the Gigabit Ethernet and supports the UDP communication protocol.(4) Using the network detection of assistant as a testing tool for receiving data. By setting the debug assistant to detect the working state of the whole circuit board, and record the data.To sum up, this topic designs a complete set hardware of the ultrasonic detection system with the method of the transmission with double probes, contains the design of the FPGA. It performs stable and perfect through testing.