Automated Laser Ultrasonic NDT of Carbon Fibre Reinforced Polymer Parts

We present the application and the results of laser ultrasonic scanning systems on fibre-based composites and the current state of development of this method at RECENDT. First we benchmark this technique with X-ray tomography and infrared thermography and then show a robotized scanning system dedicated for the aerospace industry. The laser ultrasonic systems use a 532 nm Nd:YAG pulsed laser for excitation and a 1064 nm two-wave-mixing interferometer for detection. The fibre coupling enables a flexible scan head for the automation of the system. The laser ultrasonic technique is demonstrated on a sample with artificial defects, such as PTFE-foils as a delamination source. The results are compared with reference NDT-methods such as X-ray computed tomography and active thermography, and the individual advantages and disadvantages are discussed. Further, a robotised scanning system will be presented, which has been developed under the H2020 Clean Sky 2 project ACCURATe. The sampling rate of this system is 400 Hz, which enables large parts to be inspected at the required speed. A large aircraft part made of carbon fibre reinforced polymer was manufactured and investigated for real world defect measurements.