Lamination Parameters for Sandwich and Hybrid Material Composites
x = Design variables ξ = Lamination parameters A = Membrane stiffness matrix B = Membrane-bending coupling matrix D = Bending stiffness matrix Ui = Lamina invariants θ(z) = Stacking angle distribution θi = Stacking angle of the ith ply ε = Strain σ = Stress • [C,T ] = Allowable in compression (C) and tension (T) E[1,2] = Elastic modulus in the principal and transverse directions G12 = Shear modulus in the principal direction ν12 = Poisson’s ratio in the principal direction Exx = Elastic modulus in an arbitrary direction x