In this paper, an exponential shear deformation theory is presented for the buckling analysis of thick isotropic
plates subjected to uniaxial and biaxial in-plane forces. The theory accounts for a parabolic distribution of the
transverse shear strains across the thickness, and satisfies the zero traction boundary conditions on the top and
bottom surfaces of the plate without using shear correction factors. Governing equations and associated boundary
conditions of the theory are obtained using the principle of virtual work. The simply supported thick isotropic
square plates are considered for the detailed numerical studies. A closed form solutions for buckling analysis of
square plates are obtained. Comparison studies are performed to verify the validity of the present results. The
effects of aspect ratio on the critical buckling load of isotropic plates is investigated and discussed
