Delamination detection in composites by laser ultrasonics

In this paper an application of Laser Ultrasonics (LU) is presented on laminate panels. The method exploits a high energy pulsed laser generating ultrasonic waves on the material where it impinges and laser Doppler Mach-Zehnder interferometer for measuring the ultrasonic waves propagating on the testing object. The laser-ultrasonic has been applied to a thin Carbon Fiber Reinforced Polymer (CFRP) test sample where two different depth delaminations have been created. It will be demonstrated that the measurement system is extremely sensitive to the propagation of the ultrasonic waves generated by the high energy pulsed laser source and to the multiple reflections caused by the delamination even when this latter is located in depth