BUCKLING AND POST BUCKLING ANALYSIS OF A COMPOSITE PLATE UNDER COMPRESSIVE LOADS

Abstract

In the present study, nonlinear static stability analysis of orthotropic simply–supported laminated plates under uniaxial and biaxial compression loads is analytically investigated. The used laminated composite plates are made of unidirectional reinforced fiber (graphite) and matrix (epoxy), which are utilized in many advanced engineering structures. The equations of motion for the laminated plates are derived using the first-order shear deformation plate theory (FSDT) with Von-Karman-type nonlinearity formulations and the minimum total potential energy principle. Thereafter, by displaying a two-step perturbation technique, the achieved nonlinear differential equations are solved. Then, the critical buckling loads and post-buckling equilibrium paths of the symmetrically laminated composites solved by Matlab software code. Results are shown in the form of plots presenting the variation in dimensionless buckling load parameters with dimensionless maximum deflection. The validation of the proposed research was gained by comparing some numerical results with the other published researcher, in which offered a very good agreement with the presented results. Furthermore, the effect of several parameters such as different biaxial loads, and aspect ratio (a/h) on the critical buckling loads and post-buckling equilibrium paths of graphite/epoxy orthotropic laminated plates are studied and detailed perceptibly. From the results, the maximum critical buckling loads are 217.9, and 111.6 under unequal biaxial compression loads, and under uniaxial load at (a/h) = 25, respectively. Also, the maximum post buckling strength of structure at unequal biaxial compression loads, and under uniaxial load at (a/h) = 25, respectively.