Sb. Singh et S. Ray, Steady-state creep behavior in an isotropic functionally graded material rotating disc of Al-SiC composite, MET MAT T A, 32(7), 2001, pp. 1679-1685
Steady-state creep response in a particle-reinforced-isotropic functionally
graded material (FGM) disc with linear variation of particle distribution
along the radial distance has been investigated and compared with that of a
disc containing the same amount of particle distributed uniformly. In view
of the application of rotating discs in friction drives, turbines, and a n
umber of other machine components, which are often exposed to elevated temp
eratures, weight saving without impairing the creep response may be a desir
able goal. The disc under investigation is made of a composite containing s
ilicon carbide particles in a matrix of 6061 aluminum alloy, and the steady
-state creel; response of the composite is described by Norton's law. The m
aterial parameters of creep vary along the radial distance in the disc due
to varying composition, and this variation has been estimated by regression
fit of the available experimental data. The present analysis indicates tha
t the tangential stress increases due to increased density caused by a high
er particle content in the region near the inner radius of the FGM disc, Bu
t it is more than compensated by the lowering of creep parameters due to in
creased particle content, and consequently, the steady-state creep rate dec
reases compared to those estimated in a disc with the same average particle
content distributed uniformly. In the region near the outer radius, the ta
ngential stress decreases and the creep parameters increase, both due to re
latively lower particle content. But the resulting lower tangential stress
is able to decrease the creep rate in this region overcoming the effect of
increased creep parameters. Thus, for the assumed linear particle distribut
ions in an isotropic rotating disc, the steady-state tangential and radial
creep rates are smaller by almost an order of magnitude compared to those i
n an isotropic disc with uniform particle distribution.