Optimal buckling loads of nonuniform composite plates with thermal residual stresses

Optimal elastic buckling loads of spatially heterogeneous plates formed fro m a series of composite patches is considered. Reissner-Mindlin laminated c omposite plate theory including thermal effects is adopted for the analysis and the problem is solved using the finite element method based on a bi-cu bic Lagrange C-o element formulation. The thermal residual stresses conside red are those that result during elevated temperature processing because of the different laminates forming the patches of the plate. In the optimizat ion, the fiber angles in each patch are the design variables and three symm etric laminated plate configurations ale investigated. The results illustra te that thermal residual effects can lead to optimal buckling loads which a re as much as two times greater than the corresponding optimal buckling loa ds in which these manufacturing effects are ignored. The work demonstrates the importance of spatial heterogeneity as well as the significance of manu facturing-induced residual stresses in optimal design studies of composite structures.