Buckling of Elastic Composite Rods made of Micropolar Material Subjected to Combined Loads

In the present paper, the stability of a nonlinearly elastic rod with a composite structure is analyzed. It is assumed that the interior (core) of the rod is made of micropolar material, while the behavior of the exterior (coating) is investigated in the framework of a classic non-polar continuum model. The problem is studied for a case of axial compression of a rod under external hydrostatic pressure. Using the linearization method in a vicinity of the basic state, the neutral equilibrium equations have been derived, which describe the perturbed state of a composite rod. 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 compression and external pressure). An extensive analysis has been carried out for the influence of a size effect and coating properties on the buckling of elastic composite rod made of micropolar material subject to combined loads.