An efficient modelling technique for analysis of thin-walled laminated composite beams having open and closed cross sections

Abstract

This thesis contains a series of journal and conference papers focused on the development of an efficient technique based on a one-dimensional beam finite element model for analysis of thin-walled composite beams having both open and closed cross sections. The formulation derived in this study has sufficient generality for accommodating any stacking sequence of individual beam walls and it has considered all possible couplings between axial, shear, bending and torsional deformation modes of the beam. The effect of transverse shear deformation of walls and out of plane warping of the beam section is considered where provision exists to restrain or allow the cross-sectional warping. Composite laminates are generally weak in transverse shear due to their low shear stiffness relative to the extensional rigidity. Thus, it is important to incorporate the effect of shear deformation to ensure reliable predictive capability for all relevant loading scenarios. However, the implementation of shear deformation in a finite element framework has been found to be challenging. The different techniques proposed so far by other researchers to address these difficulties are unfortunately having some issues such as instability/spurious deformation modes in the results or presence of non-physical displacement components in these formulations. In this thesis, the incorporation of shear deformation within a finite element formulation for thin-walled composite beams is successfully achieved in a novel way. The proposed model is further developed for Vibration, Vibration with preloading, Buckling, Preloaded Buckling and Dynamic Stability of thin-walled laminated composite beams. Numerical examples of open sections I beams and closed section box beams are solved by the proposed approach. A large number of results obtained in this study are compared with those available in literature for the validation of the proposed model, which show a very good performance of the model. The effect of preloading in the form of axial load, end moments and their combined actions on the behaviour of these composite beams are studied.