Functionally Graded Structures

Wednesday, April 15, 2009
4:00 - 5:00 PM
Room 190 Holden Auditorium

Dr. Romesh C. Batra
Department of Engineering Science and Mechanics, Virginia Tech

One way to optimally design structures of a given topology is to suitably vary material properties in them to either minimize values of the maximum principal stress, the maximum shear stress, or another critical variable such as the strain energy density. Other possibility is to optimize structure’s topology to minimize its weight. The tailored material properties can be obtained either by composing the structure from more than one material and varying their volume fractions or by changing the molecular and the chemical structure by exposing the material to ultraviolet light, appropriate heat and chemical treatments, or other means. Materials with continuously varying elastic moduli are usually called functionally graded (FG), and structures made of such materials are termed FG structures (FGSs). Advantages of FGSs over laminated composites include the elimination of interfaces between different constituents/layers thereby avoiding points of high stress concentration. However, FGSs fabricated by continuously varying volume fractions of reinforcing particulates in a matrix may have too many surfaces where debonding between particulates and the matrix can occur. The literature on FGSs is too large to be reviewed in one talk. An attempt will be made to summarize some of the salient results.

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