A LAMINATE DESIGN FOR ELASTIC PROPERTIES OF SYMMETRICAL LAMINATES WITH EXTENSION-SHEAR OR BENDING-TWISTING COUPLING

A laminate design method for elastic properties of symmetric laminates with extension-shear or bending-twisting coupling is presented using lamination parameters which give a complete expression of laminate configurations. The elastic properties of Young's moduli, Poisson's ratios and shear modulus are represented on the lamination parameter plane. A general method is also developed for determining laminate configurations corresponding to lamination parameters. The graphical representation clarifies the relation between laminate configurations and elastic properties. Effects of extension-shear coupling on in-plane elastic properties are discussed. The elastic properties of Young's moduli and shear modulus have the maximum values when the coupling terms vanish. Two design examples are also presented which utilize bending-twisting couplings. One is concerned with the control of a cross-coupling parameter in an aeroelastic tailoring of a composite wing, and the other is concerned with the shear buckling optimization of a symmetric laminated plate.