Vibrations and Stability of Columns Loaded By Three Side Surfaces of Circular Cylinders Considering Type of Friction in Loading Heads

This paper presents the new type of head loading the columns, comprising of elements making a side surface of circular cylinders. It demonstrates a constructional solution of forcing and receiving heads, as well as theoretical considerations related to the determination of boundary conditions, taking into account the loading of needle rolling bearings or rigid elements in the loading heads. Results of experimental investigations of the free vibration of columns having various constructions of receiving heads were presented. In the case of columns for which rigid elements were installed in the receiving heads, the rigidity of equivalent rotational spring is determined, which takes into account the rigidity of the free end of the column caused by sliding friction existing in the loading head elements. The value of critical force and the course of the natural frequency against external load for given geometry and physical constants of the column are determined.