Fatigue testing of steel profiles filled with polymer concrete for machine tool body applications

Welded steel body components are commonly employed in special-purpose machine tools due to their high stiffness. However, this design approach typically results in low damping capacity. To enhance the dynamic performance of such structures, the use of polymer concrete as a filler material in closed profiles has been proposed. This paper presents the results of an experimental investigation on steel beams filled with polymer concrete. Three different polymer concrete mixtures were selected for testing. The study includes fatigue testing to evaluate whether long-term variable loading, representative of operational conditions, induces structural changes in the polymer concrete. The study analyzed the natural frequencies corresponding to the first three resonance modes, as well as the damping coefficients. Based on the measurement results, it was found that throughout the entire fatigue testing range, the variation in the sample's natural frequency ranged from 1.5 to 29.5\;Hz. In contrast, the damping coefficient varied between 0.023 and 0.161 for the tested sample. Dynamic parameters were analyzed, and the most effective indicator for assessing structural alterations is proposed by the author.