  In this paper, the effect of local defects, viz., cracks and cutouts on the
buckling behaviour of functionally graded material plates subjected to
mechanical and thermal load is numerically studied. The internal
discontinuities, viz., cracks and cutouts are represented independent of the
mesh within the framework of the extended finite element method and an enriched
shear flexible 4-noded quadrilateral element is used for the spatial
discretization. The properties are assumed to vary only in the thickness
direction and the effective properties are estimated using the Mori-Tanaka
homogenization scheme. The plate kinematics is based on the first order shear
deformation theory. The influence of various parameters, viz., the crack length
and its location, the cutout radius and its position, the plate aspect ratio
and the plate thickness on the critical buckling load is studied. The effect of
various boundary conditions is also studied. The numerical results obtained
reveal that the critical buckling load decreases with increase in the crack
length, the cutout radius and the material gradient index. This is attributed
to the degradation in the stiffness either due to the presence of local defects
or due to the change in the material composition.
