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Materials Degradation and Fatigue under Extreme Conditions.
ILLINOIS UNIV AT URBANA DEPT OF CHEMISTRY
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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.
APPROVED FOR PUBLIC RELEASE