J. Wayne Jones

Professor Emeritus

jonesjwa@umich.edu

2022 Gerstacker

T: (734) 764-7503

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Rapid Assessment of the Role of Microstructural Variability in the Fatigue Behavior of Structural Alloys Using Ultrasonic Fatigue

Collaborators: James Larsen, Jonathan Spowart (Air Force Research Laboratories)
Sponsor: Air Force Office of Scientific Research
The objectives of this research program are: (1) to advance current predictive capability for fatigue life in relevant structural materials with complex and variable microstructures; (2) to provide fundamental links between microstructure variability and fatigue life that informs alloy design for fatigue resistance; and (3) to investigate ultrasonic fatigue methodologies as an effective tool for rapid assessment of fatigue behavior in structural alloys important to Air Force needs. These objectives are being met by using ultrasonic fatigue as the primary tool to examine the role of microstructural variability and fatigue lifetime in an  +  titanium alloy and in a discontinuously reinforced aluminum alloy. Ultrasonic fatigue is used to conduct fatigue tests at a frequency of 20 kHz on standard sized samples, allowing 109 cycles to be accumulated under normal operating conditions in one day, rather than the months required using conventional fatigue testing techniques. Targeted microstructural characterization and detailed observations of crack initiation and short crack propagation behavior are providing the necessary correlations between microstructural variation and fatigue life. A unique database of very long life fatigue behavior in structural alloys is being created for validation of existing and new probabilistic models for fatigue life prediction. The research involves a collaborative microstructural characterization effort between the University of Michigan and the Air Force Research Laboratory.