M. Kulak, J. Liu, G. Dixon, W. H. Grassel, R. L. Brazill, M. B. Heinimann, R. J. Bucci, H. R. Zonker, J. Scheuring, Alcoa, Inc., Alcoa Center, PA
Metallic structural solutions are mistakenly perceived to be near the top of the "S" curve with regard to providing significant weight savings for the next generation commercial transport aircraft wing structure. Alcoa believes that the combination of advanced alloys, new innovative structural concepts, and novel manufacturing techniques can result in greater than 20% weight savings for the wing covers and provide significant airframe cost reductions over current state of the art wing structures. Alcoa is in the second year of an ambitious R&D initiative to develop product/design solutions that achieve these goals. Using generic structural sizing methods and custom developed software design tools, studies have been conducted to identify the most promising structural concepts for lower wing skin/stiffener panels. Currently, large scale articles are being tested to validate the feasibility of these lower wing concepts for further scale-up and optimization. In phase 1 twenty six panels were designed, built ,and tested. Additional panels are planned for Phase 2 (2nd half 2006) including new concepts. The 30 in.(762 mm) wide by 90 in. (2286 mm) long stiffened panel test tests simulate a Damage Tolerance repeat inspection interval scenario and a Two Bay Crack Residual Strength design scenario. Supplementary static strength and fatigue tests are also being conducted. Comparison of static strength, fatigue,damage tolerance, and residual strength of the baseline structure to the advanced concept will demonstrate the weight saving potential. This presentation will include an overview of the testing program and the Phase 1 results. Panel concepts include advanced aluminum and aluminum-lithium alloys, hybrid concepts which utilize fiber metal laminates for selective reinforcement, and friction stir welded integral panels (reinforced and non-reinforced with) as a means to reduce cost.
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