ABSTRACT
This paper gives a model of twenty-seven degrees of freedom for a six-axle locomotive with three-axle bogies, sets up the numerical bifurcation method as the method of nonlinear lateral stability analysis of a locomotive, and derives criteria of stabillity analysis. This paper makes a point that the subcritical Höpf bifurcation speed Vn and the derailing speed Vd must be obtained in order to describe a complete picture of the lateral stability of a locomotive. However, the critical speed Vc is not the most important index of locomotive stability. At the end of this paper, the diesel locomotive DF9 has been analyzed for nonlinear lateral stability.
To solve the locomotive equations of motion about nonlinear lateral stability, the paper gives preference to Newmark’s predictor–corrector integration scheme as an integration algorithm, and sets up the numerical integration programs using FORTRAN language. At the same time, the aftertreatment programs have been set up.
Nonlinear geometry, changing contact areas, nonlinear suspension, nonlinear creep forces and driving motor moment are taken into account in the model. The result of analysis may be used to choose a new-type locomotive’s parameter and predict a new-type locomotive’s performance as well as remake an old-type locomotive. The analysis will be suitable for a four-axle locomotive with two-axle bogies and a four-axle passenger car with two-axle bogies by doing a little revision to the model.
