Experimental and numerical investigation of vibration characteristics of fibre-reinforced foamed urethane composite beam

Recently, a new composite material, ‘fibre-reinforced foamed urethane (FFU)’ has gained a vital momentum for applications in the railway industry. As railway sleepers and bearers in crossings and switches, the FFU elements act as a beam which redistributes the train forces onto track support. This leads to considering as a necessary part in order to underpin the reliable and safe operations of railway crossings and switches. According to the application of FFU sleepers for structural purpose in the railway system, it is relevant to investigate the free vibration behaviours of FFU composite sleepers under free vibration. The responses of their behaviours provide modal parameters, for example, natural frequencies, damping loss factors, and mode shapes. One primary factor causing cracking of FFU composite sleeper and excessive railway track maintenance cost is the free vibration of FFU sleepers in a railway track structure. This paper presents a sensitivity analysis of free vibration behaviours of an FFU composite beam. Through finite element method (FEM), FFU-beam elements were used in the FFU composite beam modelling. The dynamic characteristics of a vibrating structure are also evaluated by FEM. It is vital to note that errors in FE model are inevitable, whilst the modal data extracted from the experimental test is generally accepted to be accurate. Hence, the correlation of data between FE modelling and experimental measurement leads to the research on this project. This model focuses on the influence of modal parameters of FFU composite sleepers on the free vibration properties. Furthermore, data on the vibration mode shapes indicates the dynamic performance of the railway track, as it plays a significant role in the cracking deterioration of FFU composite sleepers.