Buckling analysis of functionally graded plates subjected to uniaxial loading

Elastic bifurcational buckling of functionally graded plates under in-plane compressive loading is studied. It is supposed that the gradients of material properties throughout the structure are produced by a spatial distribution of the local reinforcement volume fraction v(f) = v(f)(x, y, z). To analyze the problem, a method based on a combination of micromechanical and structural approaches is employed. This establishes the effective constitutive behavior at every point of a nonhomogeneous composite plate and provides a buckling criterion. The derived criterion enables one to calculate the critical buckling load R-x(cr) for a given distribution v(f)(x, y, z). Furthermore, with the aim to improve the buckling resistance of the functionally graded plate, the functional R-x(cr)(vf) is maximized. This yields an optimal spatial distribution v(f)(x, y, z) of the reinforcement phase. Results are presented for both short-and long-fiber SiC/Al plates in which the fibers are nonuniformly distributed in the x-, y-, or z-directions. The effects of length-to-width ratio of the plate, and of different types of boundary conditions are studied. Buckling load improvements of up to 100%, as compared to the corresponding uniformly reinforced structure, are shown. (C) 1997 Elsevier Science Ltd.