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A Concise Binomial Model for Nonlinear Creep-Fatigue Crack Growth Behavior at Elevated Temperatures
Jianxing Mao1,2, Zhixing Xiao3, Dianyin Hu1,2
1Research Institute of Aero-Engine, Beihang University, Beijing 100191, China.
Materials (Basel, Switzerland)
|January 21, 2022
Summary
Creep-fatigue crack growth in GH4720Li superalloys is influenced by temperature and dwell time. A new binomial model accurately predicts this behavior, aiding turbine disk damage tolerance assessments.
Area of Science:
- Materials Science
- Mechanical Engineering
- Fracture Mechanics
Background:
- Creep-fatigue crack growth is complex due to material behavior variations.
- Nickel-based superalloys like GH4720Li are critical for high-temperature applications.
Purpose of the Study:
- To experimentally evaluate creep-fatigue crack growth in GH4720Li.
- To develop and validate a predictive model for this phenomenon.
Main Methods:
- Systematic creep-fatigue crack growth experiments at varying temperatures, stress ratios, and dwell times.
- Development of a binomial crack growth model incorporating linear and nonlinear terms.
- Model validation against experimental data.
Main Results:
- Observed a transition from fatigue-dominated to creep-dominated fracture with increased dwell time at 600 °C.
- Identified creep-dominated fracture at 700 °C irrespective of dwell time.
- Achieved a correlation coefficient > 0.9 for 10/12 datasets, confirming model accuracy.
Conclusions:
- The study provides crucial creep-fatigue crack growth data for GH4720Li at elevated temperatures.
- The validated binomial model enhances understanding and prediction of creep-fatigue behavior.
- Findings support damage tolerance assessments for turbine disks.
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