Analytical/experimental behavior of anisotropic rectangular panels under linearly varying combined loads

An analytical solution has been obtained for the buckling of anisotropic rectangular panels subjected to several combinations of uniform shear and linearly varying biaxial in-plane loads, The principle of stationary value of the total potential energy was used for determining the buckling load of symmetric laminates through the solution of an eigenvalue problem; clamped and simply supported boundary conditions along edges mere introduced into the analysis. The analytical results are in good agreement with the results concerning isotropic plates and the few results on infinitely long anisotropic plates, The buckling load of panels under linearly varying biaxial in-plane loads is largely influenced by the transverse compression load and by the boundary conditions along the four edges. Because no experimental results were found in the open literature, several tests were carried out on a graphite-epoxy rectangular panel to verify buckling behavior under various loading conditions, 1) uniaxial compression, 2) biaxial compression, and 3) biaxial compression with uniform load in the longitudinal direction, and three transverse load conditions, 1) trapezoidal, 2) triangular, and 3) in-plane bending. The maximum transverse load was of the same value as the longitudinal compression load; the panel was clamped along the four edges. A numerical analysis was also carried out by using the MSC/NASTRAN/PATRAN finite element code. The analytical, numerical, and experimental results show extremely good correlation.