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Modeling of the Fracture Properties of Brittle Functionally Graded
Materials

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Introduction

Functionally graded materials (FGMs), like other composites, are
designed to achieve levels of performance superior to that of
homogeneous materials by combining the desirable properties of each
constituent phase. To offset the adverse effects of discontinuities in
layered composites, the composition of an FGM is varied over length
scales that are significant in comparison to the overall dimensions of
the body. The shape of this material gradient is an important parameter
in determining the properties of an FGM structure. At small length
scales the shape of the gradient is of little importance, and the
mechanics are dominated by the size, shape and interface conditions of
a particle of one material embedded in the matrix of another. Mechanics
analyses of an FGM usually emphasize the larger-scaled phenomenon and
treat the FGM as an inhomogeneous material, employing only the
"effective" properties of the composite at any given location. It is
through the variation of these effective material properties (such as
modulus) that the nature of the spatial variations of the constituents
affects the thermomechanical behavior of the FGMs.

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Publications

**
on Statistical RKR Modeling of Mixed-Mode Fracture in Brittle FGMs:
**

Limitations
on the use of the mixed-mode delaminating beam test specimen: Effects
of
the size of the region of K-dominance by T.L. Becker, J.M.
McNaney,
R.M. Cannon and R.O. Ritchie. Mechanics of Materials, 1997.

FGM '98 Paper
HTML
PDF

Slides from USNCCM '99 HTML
PDF

(sorry, HTML slides look best with M$ Internet Explorer)

An
approximate
method for residual stress calculation in functionally graded materials
by T.L.Becker Jr., R.M.Cannon, R.O.Ritchie, Mechanics of Materials
32(2000),
pp. 85-97

Finite
crack kinking and T-stresses in fuctionally graded materials by
T.L.
Becker Jr., R.M. Cannon, and R.O. Ritchie. International Journal of
Solids
and Structures, 2001

Statistical
Fracture Modeling: Crack Path and Fracture Criteria with Application to
Homogeneous and Functionally Graded Materials by T. L. Becker, Jr.,
R. M. Cannon, and R. O. Ritchie, Engineering Fracture Mechanics, vol.
69,
2002, pp. 1521-1555

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Researchers

Ritchie Group

MSD ,
LBNL

Dept of MSME ,
UC Berkeley

Last updated 8/03