N04-009 - Military Gas Turbine Engine High-Cycle Fatigue (HCF) Mitigation

Military Gas Turbine Engine High-Cycle Fatigue (HCF) Mitigation
Navy SBIR FY2004.1

Sol No.:	Navy SBIR FY2004.1
Topic No.:	N04-009
Topic Title:	Military Gas Turbine Engine High-Cycle Fatigue (HCF) Mitigation
Proposal No.:	N041-009-1
Firm:	VEXTEC Corporation 750 Old Hickory Blvd, Building 2, Suite Brentwood, Tennessee 37027
Contact:	Robert Tryon
Phone:	(615) 372-0299
Web Site:	www.vextec.com
Abstract:	The 1999 HCF Probabilistics Steering Committee meeting indicated that material behavior is a leading root cause of HCF problems in blades, vanes, and seals. A conventionally used component lifing practice is to conduct a Goodman type analysis to estimate the resistance to HCF failure. However the true resistance of a component to HCF loading is dependent on the steady and vibratory stress gradients and the stressed volume of material. Because Goodman diagrams are based on specimens of simple geometry that do not have the same stress gradients as the component, the Goodman diagram provides only a rough estimate of fatigue response. This SBIR will build on an existing VEXTEC material fatigue response model, MICRO (microstructural-based probabilistic fatigue analysis), to properly account for the multi-scale aspect of early fatigue damage that drives the scatter in fatigue response. The ultimate SBIR objective will be to develop capability for accurately predicting HCF damage effects for a complex component (JSF 1st stage fan blade) based on a minimal amount of simple specimen data. In effect, this product will be a computationally efficient Goodman analysis that will allow for accelerated design analysis, redesign avoidance, less testing and minimal build-in design conservatism.
Benefits:	From 1982 to 1996 the Air Force attributed 56% of its fighter engine-safety mishaps to HCF related failures, while during the same period the Navy attributed 40% of its fighter engine-safety mishaps to similar occurrences. This technology presents an order of magnitude improvement over conventionally used design techniques for HCF avoidance.

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