ONE-DIMENSIONAL MODEL FOR THE ANALYSIS OF THIN-WALLED COMPOSITE BEAMS

One-dimensional model is presented for the analysis of thin-walled composite beams. Each wall is made of orthotropic layers bonded together to form a, laminate that can be anisotropic. The theory uses the Navier-Bernoulli and Vlasov models to describe bending and twist, respectively, at beam level, and the Love-Kirchhof model to define the constitutive equations at lamina level. As first result, a 5 x 5 cross-sectional stiffness matrix is obtained that relates one-dimensional generalized beam forces and moments to one-dimensional generalized displacements. Later, the cross-sectional stiffness matrix of one beam element is obtained using The Virtual Work Principle and the appropriate shape functions. This formulation allows the modeling of either open-section or closed-section beams of arbitrary section shape with arbitrary layup. Two examples of sections with circumferentially uniform stiffness (CUS) and circumferentially asymmetric stiffness (CAS) are presented for the study of extension-twist and bending-twist elastic couplings, respectively. The technique has been validated comparing the results obtained with the results deduced by other authors.