Nonlinear FE solution for thin-walled open-section composite beams

In thin-walled open-section beams made of fiber-reinforced laminates, symmetric with respect to their midplane, the bending and torsion are coupled. For this type of structural members, a nonlinear finite-element (NLFE) analysis based on the updated Lagrangian formulation is developed to solve the problem, numerically. The solution could further be expanded for bifurcation and buckling type of problems in composites. The linear and geometric nonlinear stiffness matrices are presented. The displacements of simply supported and cantilever composite channels due to static concentrated loads, applied at the midspan and the end, respectively, are measured and compared with the NLFE solution. The experimental results are in good agreement with the results of the finite-element analysis.