Location of delamination in laminated composite plates by pulsed laser holography

The location of delamination in composite laminates based on their vibration characteristics is presented in this paper. Composite materials are widely used as structural materials for aerospace engineering, because of its excellent mechanical properties such as light weight, high stiffness and anti-corrosion characteristics. This paper uses pulsed electronic speckle pattern interferometry (Pulsed-ESPI) to perform non-destructive evaluation of carbon fiber reinforced plastic (CFRP) laminate plates containing various sizes of artificial defects located at the centre of the specimen, based on vibration characteristic using double-pulsed Ruby laser with a pulse duration of 30 ns. The pulsed separation can be adjusted in between 2 and 800 μs. The main advantage of this technique over conventional ESPI is the ability to carry out measurements even under harsh environmental conditions. From the results, it seems to be effective for the detection of defects in various kinds of composite materials. In this paper, the basic principles of the technique are described briefly.