Research about carbody abnormal vibration of light rail transit based on suspension failure

Abstract The filed test about the abnormal vertical vibration was carried out on light rail transit, the frequency near 8 Hz proved to be the natural pitching motion of carbody. Then, the vertical theoretical model of vehicle was established, and the influences of suspension parameters on the system response were studied. It shows the stiffness of articulation is an important factor, which affects the carbody pitching motion seriously. Based on parameter studies, stiffness test were used to verify the results. And finally confirmed that the actual stiffness of the elastic articulation is too small than the design value. When the stiffness was increased to the design value 30 MN/m, and the test was carried out again. The results showed that the Sperling index was significantly reduced, and there was no obvious vibration around 8 Hz through STFF. It can determine that increasing the stiffness of the elastic articulation can suppress the carbody pitching motion, and then can improve the dynamic performance greatly. So it is necessary to regularly measure and modify the stiffness of elastic articulations on light rail transit, to avoid the naturel pitching mode of carbody without causing abnormal vibration. It can provide a reference for vehicle operation and design on suspension elements, especially when the vehicle needs to run at more than 50 km/h.