Axial post-buckling of thin orthotropic cylindrical shells with foam core

The post-buckling behaviour of orthotropic cylindrical shells subject to axial compression is investigated in the presence of an elastic foam core. The analysis is based on the non-linear strain-displacement relationship for thin shells, and the influence of the foam core is accounted for through a force analysis with the foam being considered as an elastic continuum. The total potential energy of the system including the strain energy, and the work done by axial force, is derived based on an assumed buckled configuration. The equilibrium configuration in terms of non-linear algebraic equations is obtained through minimising the total potential energy. The non-linear equilibrium equations are solved by use of the Newton-Raphson iterative method. The post-buckling loads as well as the classical buckling loads are calculated for the given buckling wave numbers along the axial and circumferental direction. Numerical results show the post-buckling loads have a better agreement with the experimental values than the classical buckling loads. The stabilizing effect of the foam core is also presented in detail.