An investigation on the Speed Increasing Effects on the Ride Quality and Fatigue Life of Suspension Systems in Express Coaches

In this paper dynamic performance of a passenger coach is investigated in higher speeds in presence of rail surface irregularities. The research is directed to study how the increasing of the operating speed may affect two important dynamic parameters i.e. ride quality index as well as the fatigue life of the springs used in both primary and secondary suspension systems. Rail surface corrugation is modeled by its Power Spectral Density (PSD) for three classes of rails according to the USA classifications of tracks. Using random vibration theory, dynamic matrix of the system (H(ω)) is obtained and then for the response matrix of the system one can find: