Design Of Automatic Ultrasonic Nondestructive Testing System

Ultrasonic nondestructive testing technology is widely used in the field of nondestructive testing because of its advantages in reliability,detection depth and sensitivity,application scope and cost.Based on the research and analysis of the principle and requirements of ultrasonic nondestructive testing,the ultrasonic automatic nondestructive testing system is designed,the hardware and FPGA digital logic of the system are designed,and the electrical performance of the system is tested and analyzed.The design goal and overall scheme of the system are established,and the circuit design and PCB design of ten-channel ultrasonic acquisition board are completed.In the circuit design,the model of transmitting control circuit,receiving control circuit and signal conditioning circuit is extracted,the device parameters are determined by simulation analysis,and the design of ultrasonic synchronous scanning circuit is completed.The USB 2.0 and other circuits are completed around the embedded core board composing the data processing and transmission circuit.Based on the analysis of power consumption of system hardware,the design of power supply network is completed.The design of PCB is guided by the theory of signal integrity.The key signals in the circuit are simulated and analyzed.The PCB layout strategy and wiring method of the transmitting control circuit,receiving control and signal conditioning circuit and high-speed digital circuit are summarized.With the idea of modularization,the digital logic of ADC sampling control,data preprocessing and USB control module based on FPGA is designed.By controlling the ADC with two channels and sampling rate of 100 Msps,combining the interpolation and filtering of digital signal,the sampling rate of 200 Msps for echo signal is realized.The timing sequence with external USB chip is designed and the depth of asynchronous FIFO in FPGA is calculated and determined.Finally,the cross clock domain processing problems encountered in the design process are analyzed and solved.Combined with the design goal of the system,the electrical performance of the Ultrasonic Automatic Non-destructive testing system is tested by the test software.Based on the simulation and analysis of the circuit parameters that affect the test results,the test methods of each index in the transmission control circuit,the reception control circuit and the signal conditioning circuit are introduced in detail.The results show that the key electrical performance indexes of the system,such as pulse overshooting,pulse rising time,crosstalk and equivalent input noise,meet the industry standards of ultrasonic testing instruments in China.