Materials Degradation and Fatigue under Extreme Conditions.
Abstract
This AFOSR University Research Initiative Program (F49620-93-1-0241) addresses complex research problems of materials degradation and fatigue in aerospace structures in severe or extreme environments. A better understanding of materials degradation and flaw initiation dynamics will be achieved through a multidisciplinary research program encompassing chemistry, surface physics, materials science and mechanics, both experimental and theoretical. The main scientific issues are as follows: (1) Understanding of stress fields and sources of stress, leading to crack formation; (2) Crack nucleation at surface defects; (3) Understanding the kinetics and dynamics by which small cracks propagate through solids; (4) Perfluoroalkylether surface chemistry, with emphasis on the decomposition reactions of specific functional groups, leading to understanding of fluid degradation and loss of lubricant properties; (5) Macroscopic rheological measurements on extreme thin fluid films at extremely high shear rates, leading to understanding of the rheology of lubricant films so thin that continuum understanding does not apply; and, (6) NMR and laser Raman scattering measurements of the dynamic structure of highly viscous fluids in contact with solid surfaces in confined geometries at high pressure and temperature.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 23, 1994
- Accession Number
- ADA331032
Entities
People
- Andrew J. Gellman
- Darrell Socle
- Jiri Jonas
- Lance Ballard
- Steve Granick
Organizations
- University of Illinois Urbana–Champaign