TECHNOLOGY AREAS: Air Platform, Materials/Processes

ACQUISITION PROGRAM: Joint Strike Fighter

OBJECTIVE: Develop and demonstrate advanced modeling techniques and programs that can be used to accurately characterize aircraft engine systems component (and/or sub-component) to determine fretting fatigue and life prediction.

DESCRIPTION: In order to ensure the flight safety of engine components, the ability to model fretting fatigue and to determine the safe life prediction of the components (and/or sub-components) is imperative. This effort should leverage existing analysis tools, methods and information where possible from existing programs (High Cycle Fatigue ((HCF), SBIR, etc.) and expand the current capabilities to include fretting fatigue crack initiation, multiple fretting crack coalescence, and both crack growth trajectory and rate in a 3D environment for a complex engine mission cycle. The failure progression rates are to be characterized from the earliest incipient fault stages, incrementally through the final component (and/or sub-component) failure stages. The development and demonstration of the methodology should be acquired through a controlled environment and/or through actual fleet failures with the later the preferred demonstration method. The goal is to develop a program or programs capable of providing an understanding of component fretting fatigue analytically through the use of advanced models. This effort will develop, demonstrate, and apply these advanced models in support of the predictive part of fretting fatigue and life prediction.

PHASE I: Develop initial concept design and define key elements of an advanced modeling program to characterize aircraft system failure progression rates from fretting crack initiation to final component failure. Develop an initial prototype-modeling program and demonstrate the feasibility of its use on an aircraft system component failure progression time history.

PHASE II: Develop a prototype modeling program or programs with the capability to characterize the described failure progression rates for several aircraft mechanical-systems components. Demonstrate how the fault failure progression rates provided by these models can be used to accurately predict a component failure event and determine the useful remaining component life at any point in time. Assess the application boundaries and limitations for these modeling techniques.

PHASE III: Develop and deliver a complete set of application modeling programs to be use on several aircraft engine systems. Integrate the failure progression rate results of these modeling programs with a comprehensive useful life determination method. Apply these modeling programs a new aircraft engine development program like the JSF.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: These advanced models would be applicable to any mechanical machine application that has fretting fatigue crack initiation and crack propagation potential to determine useful life. This is particularly true any rotating machines used in aviation, power plants, etc. The results gained from applying these failure progression rate models to particular systems would provide a significant cross over benefit to other similar applications, commercial or military.

REFERENCES:
1. Barlow, K.W., Chandra, R., "Fatigue crack propagation simulation in an aircraft engine fan blade attachment," International Journal of Fatigue, 27, 2005, pp. 1661-1668.

KEYWORDS: fretting fatigue; crack initiation; crack coalescence; crack propagation; modeling; simulation

TPOC: (301)757-0469
2nd TPOC: (301)757-0532

** TOPIC AUTHOR (TPOC) **

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