A parametric dynamic study on hunting stability of full dual-bogie railway vehicle

Abstract

Analysis is performed on the hunting stability of a full railway vehicle system composed of a vehicle body, two bogie frames, and two wheelsets for each bogie frame. Incorporated into this analysis are the nonlinear heuristic creep and flange-rail contact models. The results show that the hunting speed is most sensitive to the primary longitudinal and lateral stiffnesses, and the nonlinear heuristic creep model plays a key role in confining the hunting speed within a physically reasonable range. Eigenanalysis is performed to investigate the dynamic behavior of the vehicle in the vicinity of the hunting speed. The results reveal that there exists not only the most dominant pair of complex conjugate roots, but also its shadowed roots. The roles of these two principal pairs of eigensolutions in the hunting motion are thoroughly explored via numerical studies using bifurcation analysis and an orbital representation. It is shown that the nonlinear hunting motions before the modal transition speed mainly refer to the principal mode, and those after the critical speed refer not only to the principal mode, but also to its shadowed mode, which supports the necessity of the dual-bogie railway vehicle model in the hunting analysis.