Parametric Investigation of a Rail Damper Design Based on a Lab-Scaled Model

Track noise is one of the main issues in the development of railway networks. It is well known that rail dampers, as a cost-effective, passive means of vibration reduction, do reduce the noise; still, neither the mechanism behind their action nor the influential parameters are well understood. The main purpose of this work is to investigate the efficiency and influential parameters of a rail damper design based on a lab-scaled model of the rail-damper system and an accurate FE model. Based on experimental and numerical modal analyses and the Modal Assurance Criteria (MAC) analysis, the FE model updating technique was applied to develop a highly accurate FE model of the rail-damper system for the investigated frequency range. In a further step, the developed FE model is used in a parametric analysis to assess various damper parameters with respect to the efficiency of damping rail vibrations and, therewith, radiated noise. The investigation performed based on FE simulations demonstrates how different material and geometric parameters of the damper influence the mobility decay rate of rail vertical vibrations. The investigated parameters are the thickness of still and rubber layers, stiffness and damping loss factor of rubber layers, and pre-force in the bolts that press the layers together. It is shown that the FE model updating technique was capable of producing a highly accurate FE model despite the challenging properties of the real structure and that a combination of the lab-scaled model and the FE model represents a cost-effective approach.