Analysis of laminated composite tubular structure

Accurate tension/bending stiffness calculation of a structural member is important for a better prediction of deflection, vibration response, and buckling load of structures. This paper presents a simple analytical method to analyze laminated composite with elliptical cross section under bending. The new approaches account for the ply orientation due to radius curvature while the conventional approach using the laminate smear property is also included for comparison. In addition, finite element analysis was conducted and the results were used for comparison. Various geometric conditions were also considered. It is concluded that the present approach gives better results compared to the results obtained from the conventional method.; Increasing use of thick laminated composites requires a large model for structural analysis that results in enormous memory and computational times requirements. Hence, lumping a group of plies into a single layer to reduce the size of a problem is often applied in finite element analysis. However, during the lumping process, composite laminate is smeared as a set of material property.; This paper presents a new method of calculating the equivalent moduli and Poisson's ratio of the lumped layers and a method of recovering the layer stress from the lumped layer. Unlike the conventional approach, the present model of equivalent properties accounts for effects of extension and shear coupling and extension and bending coupling.; A composite tube subjected to tension, bending and torsion is used as an example to demonstrate the applicability of the present approach for layer lumping. Unbalanced and unsymmetrical lumped laminates were considered. It is concluded that the present approach of the lumped layer model gives accurate stress results compared to the results obtained from the conventional method.