Ultrasonic Inspection of Thin High Performance Composite Structures

Abstract

As more and more composite materials are used for air and surface crafts, reliable and accurate nondestructive inspection techniques are required not only for the manufacturing process but also for the maintenance of high performance crafts. Voids (porosity) and delaminations are common NDI problems for composites structures. In an extreme environment, such as near jet engine exhausts, materials experience heat and vibration close to the design limits. Immersion ultrasonic technique is not a viable method for a craft as big as a jumbo jet. An ultrasonic probe and inspection technique that can be carried out with a portable system have been developed for inspection of thin and multilayered (< 50 mils) composite structural layers. Laboratory test results show that the individual layers, less than 10 mils, can be inspected reliably and accurately.