Small Business Innovation Research/Small Business Tech Transfer
Characterization and Modeling of Residual Stress and Cold Work Evolution in PM Nickel Base Disk Superalloy
Project Description
Powder metal (PM) superalloys used for critical compressor and turbine disk applications are prone to fatigue failures in stress concentration features such as holes and radii, as well as from corrosion pits and inclusions. Residual stress and cold work will have a dramatic impact on the fatigue performance. Shot peening is widely used on PM disks to provide a fatigue benefit however, the relaxation due to thermal and mechanical loads can reduce or even eliminate the compressive residual stresses and increase the risk of a catastrophic disk failure. Up to now the evolution of the residual stress and cold work under typical operating conditions in PM disk superalloys is not well understood. In Phase I proprietary x-ray diffraction (XRD) techniques will be used to simultaneously measure the change in residual stress and cold work for fatigue specimens tested in a manner to approximate in-service conditions. XRD residual stress and cold work results will be used to establish the feasibility of applying analytical or empirically based modeling techniques to predict the residual stress and cold work evolution. The modeling technique will first be demonstrated on fatigue samples and further developed and proven on actual disk hardware in Phase II. The anticipated beginning and ending technology readiness levels (TRLs) for Phase I are 2 and 5, respectively.
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Anticipated Benefits
Applications for quantification and modeling of the residual stress and cold work outside of NASA are significant. Non-NASA applications are much the same as those listed above. Engine OEM's and their suppliers can use the predictive tools developed in this program to thoroughly understand how residual stresses and cold work change during the life cycle disks. Furthermore, the OEMs can use the measurement and modeling tools to develop more robust surface enhancement processes that remain stable at high temperatures and stresses, producing higher fatigue strengths, and safer longer lasting performance.
The proposed development program will provide the following for NASA applications: · A multi-functional modeling tool to be used in NASA's Aviation Safety Program to provide longer lasting and safer compressor and turbine disk operation. · A means of measuring residual stress and cold work depth distributions simultaneously in critical high stress regions of disks. · A software tool that will allow for accurate assessment of the change in residual stress and cold working of disks providing a predictive capability of determining the remaining life of a part. · A means of developing surface enhancement processes that can produce the optimal compressive residual stress and cold working for maximum residual stress stability through the life of the part. · The model will allow for NASA engineers to understand the full stress state of the disk (applied + residual) as a function of life for a much more accurate interpretation of fatigue life. · This development will ultimately assist NASA in achieving their goal of safer and more reliable operation of legacy and new production aircraft. More »
The proposed development program will provide the following for NASA applications: · A multi-functional modeling tool to be used in NASA's Aviation Safety Program to provide longer lasting and safer compressor and turbine disk operation. · A means of measuring residual stress and cold work depth distributions simultaneously in critical high stress regions of disks. · A software tool that will allow for accurate assessment of the change in residual stress and cold working of disks providing a predictive capability of determining the remaining life of a part. · A means of developing surface enhancement processes that can produce the optimal compressive residual stress and cold working for maximum residual stress stability through the life of the part. · The model will allow for NASA engineers to understand the full stress state of the disk (applied + residual) as a function of life for a much more accurate interpretation of fatigue life. · This development will ultimately assist NASA in achieving their goal of safer and more reliable operation of legacy and new production aircraft. More »
Primary U.S. Work Locations and Key Partners
| Organizations Performing Work | Role | Type | Location |
|---|---|---|---|
| Lambda Research | Lead Organization | Industry | Cincinnati, Ohio |
Glenn Research Center
(GRC)
|
Supporting Organization | NASA Center | Cleveland, Ohio |
Primary U.S. Work Locations
-
Ohio
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This is a historic project that was completed before the creation of TechPort on October 1, 2012. Available data has been included. This record may contain less data than currently active projects.