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CivilComp Proceedings
ISSN 17593433 CCP: 79
PROCEEDINGS OF THE SEVENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and C.A. Mota Soares
Paper 23
Optimizing the Composition of a Functionally Graded Material F.C. Figueiredo, L.A. Borges and F.A. Rochinha
Mechanical Engineering Department  COPPE/POLI, LMS  Solid Mechanics Laboratory, Federal University of Rio de Janeiro, Brazil F.C. Figueiredo, L.A. Borges, F.A. Rochinha, "Optimizing the Composition of a Functionally Graded Material", in B.H.V. Topping, C.A. Mota Soares, (Editors), "Proceedings of the Seventh International Conference on Computational Structures Technology", CivilComp Press, Stirlingshire, UK, Paper 23, 2004. doi:10.4203/ccp.79.23
Keywords: functionally graded material, finite element, optimization, thermal stresses.
Summary
It is well known that abrupt transitions among different materials
with different properties often result in a sharp local
concentration of stress, either being the stress be internal or
applied externally. Therefore, such stress concentration is
greatly reduced if the transition from one material to the other
is gradually made. By definition, Functionally Graded Materials,
FGM, are used to produce components featuring gradual transitions
in microstructure and composition, the presence of which is
motivated by functional performance requirements that vary with
location within the part. Functionally Graded Materials have the
potential to improve the thermomechanical mechanical
characteristics of a component: the magnitude of thermal stresses
can be minimized; severe stress concentration and singularities at
intersections between free edges can be suppressed. In general,
heatresisting Functionally Graded Materials are composed of three
layers, ceramic and metal layers and a graded layer, such that the
material composition in the middle graded layer varies from
100% ceramic at the ceramicgraded layer interface to
100% metal at the opposite interface. In such advanced
material, the thermomechanicalmechanical behavior of FGM 's is
strongly influenced by the spatial distribution of the volume
fraction. Therefore, determining the volume fraction distribution
becomes a crucial part in a FGM design. Selecting the most
suitable volume fraction distribution becomes an essential part
for tailoring a FGM that optimally meets the desired performances
under preset geometry, loading and boundary conditions. This
volume fraction optimization problem is defined and the "downhill"
optimization algorithm is used to solve the problem. It is worth
mentioning that the use of this kind of algorithm avoids
computation of gradients. The novelties of this paper are the
development of a simple onedimensional finite element approach to
describe the thermal and mechanical behavior of a metal/ceramic
FGM hollow cylinder and the adoption of the heuristic algorithm
"downhill" in the numerical solution of the volume fraction
optimization problem.
References
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