NSF Young Investigator

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9458061 Schadler Micromechanics problems critical to the failure of composite materials are examined. Laser Raman Spectroscopy (LRS), which can measure strain and phase changes with 2 micron spatial resolution, and x-ray stress analysis are the primarily tools used. Hydroxyapatite (HA), a ceramic material present in teeth and bones, is inherently brittle and, as a man-made material, is limited to nonstructural applications. Using LRS, the toughening of HA with zirconia is studied and the transformation zone mapped as a function of load, exposure to physiological solutions, and volume fraction of zirconia. Aqueous and organic environments are known to decrease the mechanical properties of graphite/epoxy composites. Degradation of the interface during exposure is a primary mechanism of composite failure. LRS is employed to monitor the integrity of the interface as a function of solvent polarity, temperature and time. In pursuit of computer-aided instruction techniques, appropriate hardware and software will be developed for use in polymer education. %%% This research should assist in the development of composite systems for structural applications. ***