a, b: Length and width of shell in plan
: Length and width of cutout in plan
bst: Width of stiffener in general
bsx, bsy: Width of X and Y stiffeners respectively
dst: Depth of stiffener in general
dsx, dsy: Depth of X and Y stiffeners respectively
{de}: Element displacement
E11, E22: Elastic moduli
G12, G13, G23: Shear moduli of a lamina with respect to 1, 2 and 3 axes of fibre
H: Shell thickness
Mx, My: Moment resultants
Mxy: Torsion resultant
Np: Number of plies in a laminate
N1-N8: Shape functions
Nx,, Ny: Inplane force resultants
Nxy: Inplane shear resultant
Qx, Qy: Transverse shear resultant
Ry,: Radii of curvature of shell
u, v, w: Translational degrees of freedom
x, y, z: Local co-ordinate axes
X, Y, Z: Global co-ordinate axes
zk: Distance of bottom of the kth ply from mid-surface of a laminate
α,β: Rotational degrees of freedom
εx, εy: Inplane strain component
γxy, γxz, γyz: Shearing strain components
ν12, ν21: Poisson’s ratios
ξ, η, τ: Isoperimetric co-ordinates
ρ: Density of material
σx, σy: Inplane stress components
τxy, τxz, τyz: Shearing stress components
ω: Natural frequency
: Non-dimensional natural frequency