Supporting the Georgia Tech College of Engineering's Strategic Directions
Energy: Durability of High-Temperature Materials for Power Generation
- Figure 1. Cracks formed in a Ni-base superalloy under combined creep-fatigue loading in oxidizing environment (groups of R.W. Neu and D.L. McDowell).
Energy companies are designing higher-efficiency turbines for natural gas-fired power generation systems. The high inlet temperatures in these systems demand further evaluation of the Ni-base superalloys used to fabricate blades, vanes, and rotors in these hot sections. Advanced physics-based models for prediction of thermomechanical fatigue life of the next generation's Ni-base superalloys are being developed to enhance life assessment and management tools. Experiments are conducted in the Mechanical Properties Research Laboratory (MPRL) to develop and validate models that capture fatigue, creep, and environmental effects on crack formation and growth. Recent advances include capturing the effect of crystallographic orientation, which is significant for modeling cyclic deformation in directionally solidified and single crystal turbine blades.
Load-Bearing Surfaces in Advanced Propulsion Systems
- Figure 2. High temperature fretting machine in MPRL (group of R.W. Neu).
Advances in propulsion systems for aircraft are often limited by the mechanical performance of the surfaces of the high-load bearing components, such as roller-bearing raceways and the dovetail connection between the blade and disk. Increased power and efficiency demand that improvements be made in the microstructure near these surfaces. Experiments are conducted in the MPRL to simulate fretting contacts. The results are used to develop and validate models that capture the effect of the key microstructure features, such as crystallographic orientation of the grains in the alloy, the effect of different volume fraction and distributions of phases, and defects like oxide inclusions.
As shown in Figure 4. below, experiments within the MPRL are combined with multiscale modeling to achieve a means to predict the relation between microstructure variability and property variability (e.g. fatigue) in advanced alloys for propulsion systems.
- Figure 3. Explicitly modeling individual grains in the microstructure yields more realistic response for predicting structural performance (groups of R.W. Neu and D.L. McDowell).
- Figure 4. A combined bottom-up and top-down strategy for modeling realistic 3D microstructures in dual-phase alloys (in this case α-β Ti alloys), with the benefit of predicting the associated variability of mechanical properties and behaviors (group of D.L. McDowell).