MINIMUM WEIGHT AND DEFLECTION DESIGN OF THICK SANDWICH LAMINATES VIA SYMBOLIC COMPUTATION

Optimal designs of thick laminated sandwich plates are given based on a higher-order theory of plates which include the effects of the normal and shear deformation. Two designs are considered, namely, the minimum weight design and minimum deflection design. The surface layers are made of a transversely isotropic composite material and the core is chosen as a honeycomb material. In the minimum weight design problem, the core thickness and the fibre content of the surface layers are optimally determined by using equations of micromechanics to express the elastic constants. In the minimum deflection problem, the thicknesses of surface layers are chosen as the design variables. The higher-order theory is implemented using special purpose symbolic computation routines developed in the C programming language. The analysis is incorporated into an optimization algorithm for the minimum weight and deflection design of a three-layered sandwich plate. Numerical results are given for plates under sinusoidal loading and the effects of various input parameters are investigated. The deflection behaviour is studied and it is shown that design analysis cannot be performed using a classical theory or a shear deformable theory only for the thick panels under consideration.