Design and Implementation of Laser Ultrasonic Testing System Based on Articulated Robot Technology

In order to solve the problem of the noncontact and high precision non-destructive testing for the aircraft composites, a laser ultrasonic testing system based on articulated robot is proposed in this paper. In the design of the system, a 1064 nm Nd: YAG pulse laser is used to excite the ultrasonic wave, and a laser interferometer based on photorefractive effect is used to measure the ultrasonic signals. The exciting and detecting laser are transmitted through the optical fiber to the focusing module and then projected on the surface of the detected object. A precise six-axis articulated robot is used as the scanning mechanism for C-scan imaging. The laboratory prototype of the system is built. The laser ultrasonic C-scan testing of the carbon/epoxy composite specimen is realized, and the distribution, shape and size features of the simulated internal defects are characterized. The effectiveness of the system is verified. The results show that the robot assistant laser ultrasonic testing system is capable of detecting the internal delamination with a diameter larger than ∅1 mm in carbon/epoxy composite materials, thus the system has a broad application prospect in the nondestructive testing of aircraft composite structures.