A 24 dof four-node flat shell finite element for general unsymmetric orthotropic layered composites

The constitutive relationship of a four-node flat shell finite element with six degrees of freedom per node and a modified five-point quadrature, previously presented by the authors, is extended to include symmetric and unsymmetric orthotropy. Through manipulation of the kinematic assumptions, provision is made for out-of-plane warp. A wide range of membrane and thin to moderately thick plate and shell examples are used to demonstrate the accuracy and robustness of the resulting element.