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

Abstract

Subway rail vibrations are a major source of structural deterioration, environmental noise, and passenger discomfort in urban railway systems. Here, we present a broadband design methodology for railway tuned mass dampers (TMDs) based on the concept of joining multiple locally resonant bandgaps. The proposed framework begins with an experimental modal analysis of a UIC60/60E1 rail to identify its dominant vibration modes and develop an equivalent dynamic model. Guided by the proposed bandgap-joining strategy, single- and multi-resonator TMDs are subsequently designed, fabricated, and experimentally validated before being implemented on the railway track. The experimental investigation demonstrates that the tuned single-resonator configuration reduces the vibration amplitudes at the dominant resonances by up to 74\%, while incorporating a second resonator further broadens the effective attenuation bandwidth, confirming the advantages of the proposed multi-resonator concept. Finally, a random vibration analysis is performed to evaluate the effectiveness of the designed TMDs under stochastic excitations representative of practical railway operating conditions, predicting an average reduction of approximately 12\% in the RMS vibration response. The proposed methodology provides a practical framework for translating locally resonant metamaterial concepts into compact, manufacturable, and non-invasive railway vibration absorbers with enhanced broadband vibration mitigation capabilities.