T. Warner, Alcan, Voreppe, France; P. Lassince, C. Bersuder, ALCAN Rhenalu, Issoire, France; K. P. Smith, C. Boland, Alcan Rolled Products, Ravenswood, WV
The proportion of metallic structures in the large commercial airframes currently in development is significantly lower than in comparable previous generation aircraft. Our analysis of the underlying reasons indicates that the airframers’ decisions are based on both quantifiable arguments (technical and economic) and less quantifiable parameters. Technically, it is argued that CFRP panels have a significant weight advantage particularly in damage tolerance- or stiffness-dominated parts. Equally, it is generally recognized that metallic solutions are currently lower cost. Less quantifiable arguments include: the future potential of CFRP structures, the concomitant technological gap with newcomers to the large commercial airframe business that could be created by developing such solutions, and the advantage of CFRP’s relative novelty in obtaining government support for development activities.
This analysis has led Alcan to respond around four principal axes. Firstly, in response to the weight challenge we have developed very competitive metallic solutions using optimum existing technologies (alloys, assembly techniques) in innovative ways. This approach has resulted in solutions exceeding 20% weight reduction vs today’s aerostructures, at lower cost, and applicable to a wide variety of airframes. Secondly, in many cases combinations of materials represent optimum weight-cost solutions; to enable this, technologies for hybrid joining need to be optimized. Thirdly, to address the perception of lower future potential of metallic structures, we are both increasing our effort on breakthrough metallic technologies and developing a more aggressive communication on metallic structures’ advantages, for example emphasizing the full recyclability of aluminium. Finally, we are instigating a more balanced co-development strategy, by partially redeploying our resources from the development of generic solutions for large airframes to more targeted projects addressing a greater variety of specific customer developments.
Examples of achievements and on-going development in the above four areas will be presented.
Summary: Based on an analysis of the reasons for airframers' recent choices between metallic and CFRP structures, some axes for future metallic aerostructures developments are proposed. These include: developing very competitive metallic solutions using optimum existing technologies (alloys, assembly techniques; optimizing technologies for hybrid joining; increasing effort on breakthrough metallic technologies; and developing a more aggressive communication on metallic structures’ advantages, for example emphasizing the full recyclability of aluminium.
Examples of achievements and on-going development in the above four areas will be presented.
