Buckling load optimization of composite shells taking thermal manufacture effects into account

Abstract

This paper deals with optimization of the buckling load for laminated composite structures. A new methodology has been developed where thermal residual stresses introduced in the manufacturing process are included in the buckling analysis, see (Foldager 1999). The thermal effects are also included in the calculation of the buckling load sensitivities, and it is therefore possible to 'tailor' the thermal residual stresses in order to increase the buckling load. The design variables in the optimization problems are the fiber directions in the laminates. very sensitive to geometrical imperfections and by including those in the analysis it is possible to obtain better agreement between theory and practice. However, in the studies above the effects of thermal residual stresses have not been taken into account in the buckling analysis of anisotropic cylindrical shells. In the present work, the thermal residual stresses have been included, and it appears to have a two-fold advantage. First, it is possible to increase the buckling load significantly for plates and shells. Secondly, shells which have been optimized ignoring the effects of thermal residual stresses, may have a buckling load which is much less than expected when the effects of the thermal residual stresses are included.