(MEANS2) Development of microstructure and micro-mechanism- sensitive property models and their integration into the design of advanced disk and blade systems
Sponsor: Air Force Office of Scientific Research
PI: M.J. Mills, Co-PI: S. Ghosh, J.C. Williams, K. Flores, G. Daehn, Y. Wang, J. Li
Keywords: Creep
Abstract:
The ultimate vision for this EFA is to provide an alternative to the costly and time-intensive mechanical testing in the development of the materials models presently used in the design of turbine engines. Turbine engine performance and fuel efficiency goals mandate higher temperature environments for both disks and blades. However, the constitutive laws for creep, fatigue and crack growth that are currently used in design are completely empirical. Therefore, extensive test matrices are needed for development of these equations.
The proposed program builds upon the DARPA Accelerated Insertion
of Materials (AIM) program, including a close collaboration with materials
and design engineers at Pratt & Whitney (PW) and General Electric
Aircraft Engines (GEAE). It was well documented in AIM that property
models containing information about microstructure are largely absent
in the literature for engineering alloys, and that development of
these models is one of the key challenges. Furthermore, AIM demonstrated
that if we have microstructure (and chemistry) in our property models,
then there is a path available for definition of new materials with
better properties and also a path for assessing material variability.
Because of this groundwork laid in AIM, we will probe more deeply
into mechanistic details, by combining critical experiment and multi-scale
modeling, and hence develop modeling tools of the highest fidelity.
At the same time, we will capitalize and expand upon the path to the
design process at both PW and GEAE that was blazed in AIM. In addition,
this MEANS-2 program will foster a natural, synergistic relationship
with several ongoing thrust areas at the AFRL.
The proposed EFA is clearly quite broad and we will further focus
our efforts on several specific objectives and alloy systems. With
respect to materials, we plan to concentrate on the disk alloy ME3/ME16,
and the single crystalline blade alloys PWA1497/RN6. These alloys
emerged from the NASA EPM program and are of common interest to both
PW and GEAE. The program objectives will target several of the pacing
materials issues associated with hot-section materials:
(1) Creep mechanisms and microstructure stability
of disks and blades, and delivery of physically-based deformation
models for creep of both.
(2) Determine the local plasticity mechanisms during
fatigue at high temperature, and build on the creep models to account
for the multiple mechanisms that will be active near stress risers,
including pre-existing flaws.
(3) For disks, determine the source of the environmental
effects on accelerated crack growth and develop the connection between
microstructure/heat treatment and crack growth rates.
(4) For blades, characterize the gradation of microstructure
and properties in the bond coat of the thermal protection system,
and develop appropriate material models based on the local structure
and chemistry.
An additional, overarching theme will be the direct incorporation of spatial and temporal variations in microstructure, at both the fine (e.g. precipitate) and coarse (e.g. dendrite) scales, via phase field microstructure modeling. We believe this is a crucial step toward including microstructure-related variability in constitutive materials models.
OSU Research Team
Professor: S. Ghosh,Graduate Students: To be identified
