This paper presents a method for modeling the dynamic properties of steel–polymer concrete beams, the basic structural components of machine tools, assembly lines, vibratory machines, and other structures subjected to time-varying loads during operation. The presented method of modeling steel–polymer concrete beams was developed using the finite element method. Three models of beams differing in cross-sectional dimensions showed high agreement with experimental data: relative error in the case of natural frequencies did not exceed 5% (2.2% on average), the models were characterized by the full agreement of mode shapes and high agreement of frequency response functions with the results of experimental tests. Additionally, the developed beam models supported the reliable description of complex structures, as demonstrated on a spatial frame, obtaining a relative error for natural frequencies of less than 3% (on average 1.7%). Full agreement with the mode shapes and high agreement with the frequency response functions were achieved in the analyzed frequency range.

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The article presents results of both experimental and FEM model-based investigations on chatter phenomena that occur in the end milling process. On the basis of chatter symptoms observed during machining, the mechanism of its occurrence has been identified. Then, a FEM model has been built to indicate machine tool elements responsible for loss of stability. Afterwards, experimental modal analysis has been conducted in order to validate the FEM model. Finally, on the basis of the validated model, the structural changes have been proposed and applied in the real object resulting in increased stability.