ABSTRACT
The Ultra-Low-Frequency (ULF) is obtained by connecting in parallel elements with positive and negative stiffness, in which the negative stiffness is obtained by a pair of linear springs placed horizontally. An appropriate second suspension system is designed by combining the ULF vibration absorber with the U type side frame of the tram. The stiffness characteristics and transfer rate of the second suspension system are gained respectively by static and dynamic analysis. A low-floor tram model with three cars is established by SIMPACK, which is co-simulated with MATLAB/SIMULINK. The results show that compared with the equivalent linear suspension, the ULF suspension is of extent isolation frequency and better vibration isolation characteristics especially in the low frequency range. The low-floor tramcar with second ULF suspension is of lower vibration in car body, better running stability and ride comfort.
