Vibrations and stability of columns loaded by four-side surfaces of circular cylinders

The paper presents a new type of specific load realised through components making a side surface of four circular cylinders having pair-wise equal radii. This is a conservative load representing a follower force directed towards the positive pole. Theoretical considerations are made related to the determination of boundary conditions with installation of needle rolling bearings or rigid elements in the receiving head. The course of the natural vibration frequency against the external load is determined. The results of theoretical research are compared to results of experimental examinations. The rigidity of the substitute rotational spring is defined, considering "the rigidity impact" of the free end of the column.