Buckling of Sandwich Tube with Foam Core Under Combined Loading

Abstract

In the framework of a general stability theory for three-dimensional bodies the buckling analysis is carried out for the nonlinearly elastic three-layer cylindrical tube subjected to axial compression under internal or external pressure. It is assumed that the middle layer (core) of the tube is made of metal or polymer foam, and to describe its behavior the model of micropolar continuum is used. Such approach allows to study in detail the influence of foam microstructure on the deformation stability, which is especially important when the macroscopic dimensions of the tube are comparable with the average size of the foam cells. The inner and outer layers (coatings) of the tube are assumed to be made of the classic non-polar materials. Applying linearization the neutral equilibrium equations have been derived, which describe the perturbed state of the cylindrical sandwich tube. By solving these equations numerically for some specific materials, the critical curves and corresponding buckling modes have been found and the stability regions have been constructed in the planes of loading parameters (relative axial compression and internal or external pressure). Using the obtained results, the influence of coatings properties, as well as the overall size of the tube, on the loss of stability has been analyzed.