A simplified integration of multi-channel ultrasonic guided wave system for phased array detection and total focusing imaging

Abstract

Ultrasonic guided waves based on sensors array effectively improve the detection sensitivity of defects and realize the intuitive imaging of defects. In this research, a 16-channel guided wave excitation/acquisition system is simply integrated for the array focusing detection. Using a FPGA (Field Programmable Gate Array) as the main control unit, a high-voltage excitation of a multi-channel tone-burst signal with synchronous signal acquisition is designed. Experiments are conducted by the developed multi-channel system and the piezoelectric linear array. A guided wave phased array and the total focusing imaging algorithm are demonstrated on a 1mm aluminum plate. The experimental results show that the system can meet the practical requirements of guided wave array focusing detection. By combining the total focusing method and the phase-based sign coherence factor, the compounded image shows that the artifacts can effectively be reduced, and the contrast is improved. Meanwhile, this system can solve the problem of distributed sensor array detection, in which the process is cumbersome and inefficient previously. Through the system and the sensor array, the guided wave phased focusing method and the composite total focusing method can effectively improve the sensitivity and the positioning accuracy of defect detection in thin plate.