Geometrically nonlinear first-order shear deformation theory for general anisotropic shells

A generalized first-order shear deformation theory for anisotropic multilayered shells is presented. It includes the effects of geometrically nonlinear deformations and general initial curvature. The field equations are expressed in orthogonal conjugate curvilinear coordinates in the shell's middle surface. Hence, this formulation is particularly suitable for the analysis of monocoque structures formed using the increasingly exploited fiber-placement manufacturing techniques. A novel expression for the stiffness matrix is presented in which the relationship between the shell shape and the stiffness coefficients is highlighted. It is also shown that the stiffnesses herein obtained may lead to significantly different deformation fields from those based upon flat-plate expressions.