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           COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER
                              College of Science
                       (CDS Department CSI 898-Sec 001)
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        Microstructure-Property Simulations for Low Thermal 
                  Expansion Ceramic Composites

                     Edwin R. Fuller, Jr.
 National Institute of Standards and Technology, Gaithersburg, MD

Two- and three-dimensional microstructure-based finite-element 
simulations are used to investigate the thermal expansion behavior 
and inherent residual stresses of low thermal expansion ceramic 
composites. Such composites have myriad applications, for example, 
in precision optical devices, turbine engine heat exchangers, and 
domestic cook-tops. Typically, they are a polycrystalline composite 
of a negative thermal expansion material[e.g., beta-eucryptite (LiAlSiO4)] 
with small amounts of a positive thermal expansion ceramic [e.g., alumina]. 
As such, they develop very large thermally-induced residual stresses, 
and hence stored elastic strain energy in the microstructure, which 
can lead to micro- and macro-cracking. The nature and distribution 
of these stresses as well as the thermal expansion behavior are 
studied for composite compositions with varying beta-eucryptite to 
alumina ratios. Topological invariants of the residual stress 
isosurfaces are used to characterize the stress distributions and 
to identify potential fracture initiation sites. 

                        Monday, April 7, 2008
                                  4:30 pm
                     Room 301, Research I, Fairfax Campus

Refreshments will be served at 4:15 PM.
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Find the schedule at www.cmasc.gmu.edu/seminar/schedule.html
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