Global analysis of laminated tubes

Abstract

The finite element analysis of homogenous and isotropic tubes is a well established subject and very good results are obtained for long tubes using standard beam elements. On the other hand, the analysis of laminated composite tubes is generally carried-out using a global-local approach. This approach is performed in two levels, by means of a global analysis using beam elements with effective stiffness properties followed by the analysis of a refined local model of shell or solid elements to compute the ply stresses at critical sections of the tube. This work investigates the use of a global approach to carry-out the complete structural analysis of laminated composite beams, without the need to use a local finite element model. The successful application of beam elements depends on the accurate evaluation of effective mechanical properties of laminated tubes. In this work, the axial and bending stiffness of laminated tubes are computed by appropriate integration of segment stiffness over the tube cross-section. The internal forces obtained from the global analysis are used to compute the beam membrane strain and curvature. Ply strains are computed from the laminated strains. Finally, the stresses in the material system are evaluated using the appropriate constitutive relations. Numerical examples are presented and the results obtained by the global analysis approach are compared with results obtained by solid and shell finite elements. Very good results were obtained for most lamination schemes.