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Rapid, Low-cost Material Qualification for High-Cycle Durability of Blades in Short-Life Turbine Engines


OBJECTIVE: Develop a low-cost material qualification method to ensure high cycle fatigue durability of blades in short-life turbine engines. 

DESCRIPTION: Short-life turbine engines will push materials beyond their conventional design limits where mechanical property data does not exist. Though the general life of components will be limited, blades in the compression and turbine sections of the engine will be subject to high cycle fatigue (HCF) loading that could be as high as 10E07 to 10E09 cycles. This is exacerbated by the high rotational speeds that smaller engines will see such that even short-life engines could see HCF cycling a high as 10E07 to 10E09 cycles. Traditional data requirements to ensure HCF durability are excessive [1] and cannot be cost-effectively developed for all the materials in these short-life turbine engine systems. Thus, a new methodology to ensure HCF durability of these engine blades is required. The envisioned small, short-life turbine engines will have low-cost due to; 1) lower cost materials, and 2) simple turbine cooling schemes [2]. These engines will bring new materials and manufacturing methods (e.g., additive manufacturing) into the engine and will push them to higher temperature limits [3,4] where the cost of characterizing the material performance has to be significantly reduced. Methodologies are sought that can ensue the desired HCF performance and reliability without the long and expensive development of material databases. The preferred approach should be applicable to all materials; metals, ceramics, and composites. The cost of data generation should be a major consideration in the choice of approach as a reduction of material certification cost of 5x is sought. The specific requirements of HCF probability of failure could be best identified by a partner company. It is envisioned that the methodology would be applicable to manufactures of small, short-life turbine engines. As such, the inclusion of an OEM partner early in the research will help to identify target applications for the technology and assist in the development of a suitable technology suite for broad applicability. 

PHASE I: Develop a low-cost integrated experimental and analytical approach to rapidly assess the HCF durability of any material. The Phase 1 effort should demonstrate the suitability of the approach largely using existing data of their own, in the public domain, or available from an OEM partner for at least one of the classes of materials. That is, the approach should demonstrate the utilization of a limited set of data to predict the performance of a larger HCF data set. 

PHASE II: Refine the approach(es) based on the outcome of Phase 1 and demonstrate the capability of the approach to predict the HCF behavior of a material under conditions outside the current understanding of the material HCF performance. Validate the prediction based on suitable analytic and experimental approaches to calculate the probability of failure. The contractor will need to verify and validate the cost effective technique over the range of loading conditions required. 

PHASE III: A low-cost experimental and analytical approach to rapidly assess the HCF durability of a material could find applications in several military and commercial aerospace sectors. The contractor will have to identify these markets and applications for the technology to develop a commercialization strategy. 


1: J. Gallagher, et al., "Advanced High Cycle Fatigue (HCF) Life Assurance Methodologies," University of Dayton Research Institute, AFRL-ML-WP-TR-2005-4102 (2004).

2:  I.C. Oelrich, D. D. Weidhuner, F.R. Riddell, "Small Turbine Technology Review," Institute for Defense Analyses, IDA Paper P-1840 (1985).

3:  "Technology Requirements for Small Gas Turbines," AGARD Conference Proceedings 527, Papers presented at the Propulsion and Energetics Panel 82nd Symposium held in Montreal, Canada, October (1993).

4:  R.W. Niedzwiecki, P.L. Meitner, "Small Gas Turbine Engine Technology," NASA report AD-A238 076 (1987).

KEYWORDS: Small Engine, Design Methodology, High Cycle Fatigue, Low-cost 


Andrew Rosenberger (AFRL/RXCM) 

(937) 255-3304 

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