Fibre-reinforced laminated composite tubes with free ends under uniform internal pressure (Q1358876)

The stress and deformation fields in a fibre-reinforced composite tube under uniform internal pressure are discussed in detail. We present analytical solutions based on asymptotic approximations of the three-dimensional equations of linear elasticity for homogeneous orthotropic materials. One ``small'' parameter \(\varepsilon_R\) characterising thin shell geometry, and another ``small'' parameter \(\varepsilon_G\) following from homogenised material properties of the shell structure and whose order of magnitude is comparable with \(\varepsilon_R\) are used to derive asymptotically consistent approximate solutions. To derive boundary layer equations we replace the laminated structure by its homogeneous orthotropic equivalent. We first study as a leading example a hypothetical cross-ply structure and concentrate on transverse shear and axial normal stress distributions across the wall thickness and along the axial direction in the boundary layer region. Then we discuss two cases of symmetric angle-ply lay-ups corresponding to tubes actually tested in the laboratory and enhance similarities and differences with respect to the cross-ply lay-up. We also show how the interlaminar shear stresses which may cause delaminations and failure depend strongly on the lay-up.