# Reducing Railway Track Vibrations by Applying Particle-Damping Systems
## 1 Introduction
They have found a relation between the diameter of a specific particle material and its efficiency for a certain frequency, where larger (or heavier) particles tend to be more efficient for higher frequencies. This observation is very important in terms of designing a damper, as it can act as an initial guide for choosing the most suitable particles for reducing vibrations under certain loading conditions. Some works studied the efficiency of particle dampers in reducing vibration for several different applications, like a wind turbine stator [27], circuit boards [28], cutting tools [29], turbines [30], and engines [31], yielding promising results. One more interesting application of particle dampers was developed by [PERSON] [32]. In this work, deep learning methodology was applied to particle dampers for noise and vibration control of steel rails. Several materials and particle sizes were studied, and their damping efficiency was analysed. They were able to significantly reduce track vibrations in most test conditions, except for impact vibrations caused by the passing wheels. Regarding the railway, different vibration control analyses can be applied, focusing on the control of the vehicles themselves [33] or the infrastructure [34]. An interesting study was developed by [PERSON] et al. [35], in which a tuned particle impact (single particle confined in a reservoir) was used to minimise vibration and noise at a rail track; the vibration amplitudes and sound pressure levels were reduced by approximately half. Regardingthe applications of particle dampers in rails, a comprehensive study was conducted by [PERSON] et al. [36], where several excitation frequencies and amplitudes were studied for a certain reservoir and particles (these parameters were not changed). Solutions regarding particle dampers focusing on improving the passengers' comfort were also analysed [37], where the authors used experimental tests and the discrete element method to simulate the damping performance of the particle system. They have achieved sound level reductions by a factor of more than 2. Although scarce data can be found for railroads regarding the effect of different materials and their vibration-damping efficiency, the present research aims to address this issue. The main goal of the present work is to explore a known damping technology, particle damping, to reduce vibration levels on a steel rail. By attenuating the vibration levels, several positive outcomes may be obtained based on the present research, like reducing track and wheel wear, enhancing passenger comfort, and reducing the railway's impact on nearby buildings and community well-being. This last topic is especially important, as noise and vibration lead to several health problems (previously discussed), and mitigating them would improve essential aspects of people's lives, like sleep quality and reducing stress levels. Moreover, attenuation in vibration amplitudes is also directly related to decreases in noise levels, but this impact will not be the subject of the present work. An experimental development regarding different particle materials will be conducted. The following sections of the work will be divided into three main parts: Materials and Methods, where the detailed experimental procedure, equipment, and methodology used for the analyses will be detailed; Results, where the measured and processed data will be presented and discussed; Conclusion, where an analysis of the applied methodology and significance of the analysed data will be presented. The literature review regarding particle dampers, their origins, and the impacts of railroads presented in this section will be used as a baseline for designing an experimental procedure for this type of damper, which will be detailed in the following section.