Nonlinear analysis of angle-ply composite and sandwich laminates

A refined higher order shear deformation theory for linear and geometrically nonlinear behavior of fiber-reinforced angle-ply composite and sandwich laminates is established. Laminae material is assumed to be linearly elastic, homogeneous and isotropic/orthotropic. The theory accounts for nonlinear quadratic variation of transverse shear strains through the thickness of the laminate and higher order terms in Green's strain vector in the sense of von Karman. A simple [C.sup.0] finite-element formulation of this theory is then presented with a total Lagrangian approach, and a nine node Lagrangian quadrilateral element is chosen with nine degrees of freedom per node. Numerical results are presented for linear and geometrically nonlinear analyses of multilayer angle-ply composite and sandwich laminates. The theory is shown to predict displacements and stresses more accurately than first-order shear deformation theory. The results are compared with available closed-form and numerical solutions of plate theories and three-dimensional finite-element solutions. New results are also generated for future evaluations.