Accession Number : ADA331032

Title :   Materials Degradation and Fatigue under Extreme Conditions.

Descriptive Note : Conference proceedings,

Corporate Author : ILLINOIS UNIV AT URBANA DEPT OF CHEMISTRY

Personal Author(s) : Ballard, Lance ; Jonas, Jiri ; Socle, Darrell ; Granick, Steve ; Gellman, Andrew

PDF Url : ADA331032

Report Date : 23 JUN 1994

Pagination or Media Count : 10

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.

Descriptors :   *SYMPOSIA, *CRACK PROPAGATION, *SURFACE CHEMISTRY, *LUBRICATING FILMS, NUCLEAR MAGNETIC RESONANCE, DEGRADATION, CRACKING(FRACTURING), THIN FILMS, SHEAR STRESSES, AEROSPACE CRAFT, RHEOLOGY, FATIGUE(MECHANICS), RAMAN SPECTRA.

Subject Categories : Physical Chemistry
      Lubricants and Hydraulic Fluids
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE