Engine manufacturers have limited incentive to share their extensive property data for these materials, for legal, financial, and competitive reasons, as outlined below:

  • Materials data for the most advanced materials generated by the U.S. engine companies are often export-controlled and subject to ITAR (e.g., data for powder metallurgy disk alloys).

  • Data on engine life are highly competition-sensitive. Engine manufacturers have a disincentive to convey materials property data to competing manufacturers—particularly creep, fatigue, and hold-time low cycle fatigue (LCF) data that directly relate to calculated component life limits.

  • Engine life management depends on materials property data that are relevant to a company’s lifing methods and the processing used to produce specific engine hardware. Although material property testing is conducted to American Society for Testing and Materials (ASTM) standards, engine manufacturers often institute additional control to regulate specimen geometry, machining (surface condition and residual stress), and test protocols.

  • Shared materials property data from the wider materials community offer limited value to engine manufacturers. Without direct knowledge of material pedigree and control of testing, engine companies subject themselves unnecessarily to legitimate legal liability if data generated by the materials community are proved to be erroneous or inappropriate. Engine makers are fully committed to both flight safety and the financial risk of inappropriate engine warranties.

These legitimate industry concerns need to be balanced against the benefits of data sharing. There appears to be an appropriate level of controlled cooperative programs26 among engine manufacturers, materials and component suppliers, and external materials scientists that could reduce the cost and time to develop material property data for advanced materials.

3.4
MATERIALS CONTRIBUTION TO CURRENT AND EMERGING PROPULSION SYSTEMS

3.4.1
Turbine Engines

For more than 50 years, materials have been the major enabler for the evolution of aircraft turbine engines. At the very beginning of powered flight, the Wright brothers depended on a revolutionary new material, aluminum, for the

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 Programs that reflect intellectual property and ITAR concerns.



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