ULTRASONIC THROUGH TRANSMISSION INSPECTION OF CO-CURED CFRP AIRCRAFT COMPONENTS
H. N. Sudheendra, M. R. Madhava, M. Subba Rao and B. R. Somashekar Structures Division, National Aerospace Laboratories, Bangalore 560 017, India
Keywords: CFRP, aircraft components, co-curing technology, NDE, ultrasonic C-scan system
ABSTRACT
Carbon Fibre Reinforced Plastics (CFRP) possess attractive strength and stiffness properties and have successfully been used in airframes of both civilian and military aircrafts. The concern, at present, is to make composite airframes cost effective. Towards this goal, new fabrication procedures have been evolved. The principal aim is to obtain parts consolidation and minimize or even eliminate the use of expensive fasteners. This in turn substantially reduces assembly time and costs and add to the competitiveness of composite airframes. It is against this background, we have developed a novel co-curing fabrication technique involving the use of composite tools and rubber mandrels to fabricate a variety of integral rib-skin CFRP structural components for a high performance aircraft development programme. The non-destructive evaluation (NDE) of these co-cured components is indeed a challenging task. Over the years, we have tackled this crucial problem and have come out with a new practical procedure for the NDE using automated water squirter through transmission ultrasonic c-scan system. The intricacies of the ultrasonic NDE procedure will be discussed with reference to a CFRP integral rib-skin fully co-cured test box. The effect of off-normalcy of ultrasonic beam impinging on the component under evaluation will be elaborated. Also, the sensitivity aspects of the NDE procedure developed will be outlined.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 2, pages 711 - 714 Publisher:Ashgate Publishing Company
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