Cambridge, UK—April 25, 2012

Materials Selection for Aerospace Systems—new NASA/TM report

A recent NASA Technical Memorandum addresses the opportunities arising from systematic materials selection for aerospace systems. Taking the examples of engine blades and pressure vessels (both at room temperature and elevated temperature, where time-dependent effects are important) this paper demonstrates a systematic, design-oriented, five-step approach to materials selection:

• establishing design requirements,
• material screening,
• ranking,
• researching specific candidates, and
• applying specific organizational constraints to the selection process.

The pivotal stage is the definition of performance indices (i.e., particular combinations of material properties that embody the performance of a given component), allowing the use of powerful graphical selection charts to make trade-offs between conflicting objectives.

A material property chart showing modulus-density space, with contours of specific modulus, E/ρ. Part of the space is occupied by materials, part it empty (the “holes”). Material development that extended the occupied territory in the direction of the arrow (the “vector for material development”) allows components with greater stiffness-to-weight than is at present possible.

These graphs of material property space also reveal ‘holes’ in the property combinations available with conventional materials,  which can be addressed through engineered/hybrid materials, enabling innovation and increases in performance as compared to monolithic materials. An example of this is shown above, taken from Fig. 28 of the paper, indicating the desired areas for material development, and providing a means to assess the merit of new engineered and hybrid materials.

The report concludes with a brief discussion on managing the data needed for materials selection, including collection, analysis, deployment, and maintenance issues.

‘Materials Selection for Aerospace Systems’, by Steven Arnold, of the NASA Glenn Research Center, Cleveland, Ohio, and David Cebon and Mike Ashby, of Cambridge University and Granta Design, is available on the NASA Technical Reports Server as paper 2012-217411