Application of Laser Ultrasonics for the Non-Destructive Inspection of Complex Composite Aerospace Structures

Laser Ultrasonics is a non-contact inspection technology that uses lasers to induce and detect ultrasonic waves in a material system. LaserUTTM, the Lockheed Martin (LM) developed pulse-echo implementation of Laser Ultrasonics for composite structures, has been used to perform non-destructive inspections of over 22,000 production parts at the LM Aeronautics-Fort Worth facility since the first of two production LaserUT systems went on-line in May 2000. The systems have been approved for use on a variety of aircraft programs including the F-2, F-16, F-22 and F-35. LaserUT was considered a key discriminator for Lockheed Martin by the Joint Strike Fighter selection committee in the JSF competition. Inspection of complex-shaped composite aircraft parts, such as the inlet ducts of military aircraft or the fuselage stringer sections utilized by commercial aircraft manufacturers, has been very difficult with conventional Ultrasonic NDI systems. LaserUT is highly advantaged for applications with challenging structures that would typically require rigid tooling and custom transducer assemblies, and can be up to 10 times faster than state-of-the-art conventional UT systems. For the most complex of these structures, LaserUT is an enabling technology, allowing the inspection of part configurations previously considered uninspectable by automated systems. LaserUT greatly simplifies the NDI inspection process. LaserUT typically requires only simple, or no tooling fixtures – most parts can be inspected on a table or on the carts used for transporting them. The system is highly automated, without complicated setup procedures, 3-point alignments/corrections, gain/damping parameters, or most of the other settings and setup time typically associated with conventional ultrasonics. Gates are not required, as the system captures and stores 100% of all waveform data to support advanced data visualization techniques, in addition to standard C-scan images. The end result is an easy-to-use system that acquires the same high quality data regardless whether the operator has 20 years experience in ultrasonics, or was just qualified yesterday. LaserUT is protected by over 40 domestic and international patents, and has been licensed to PaR Systems, Inc of Shoreview, Minnesota, for commercialization of the technology.