Metamaterial Bi-stable Vibration Absorbers for Railway Tracks: Experimental Study of Flexural Wave Control

Subway rail vibrations result in serious problems in urban railway systems as they cause structural damage, as well as increase noise pollution and discomfort of passengers. This paper aims to present an experimental study on the application of Dynamic Vibration Absorbers (DVAs) to reduce unwanted rail vibrations. The effectiveness of various DVA configurations was evaluated using Experimental Modal Analysis (EMA) and stochastic vibration analysis on a UIC60/60E1 rail. The results of the study show that well-designed DVAs can decrease vibration by up to 74%, while periodic installations with a 1 m span create a grid-like structure that exhibits metamaterial behavior, enhancing suppression up to 98%. This periodic arrangement leads to attenuation in critical frequency bands due to flexural wave interference effects. Further, Random vibration analysis is also performed to assess the real performance of DVAs under stochastic excitations, and the results show that the RMS reduction is, on an average, 12%. The results of the study show that DVAs are portable, non-invasive, and very efficient systems for the management of railway vibration, as well as the reduction of the effects on the environment and enhancing the strength of the infrastructure.