Computation of Common Normal Between a Wheelset and Straight Rail at Singular Position
Computation of common normal between a pair of wheel and rail surface is an important sub problem in railroad simulations. In this study, it is shown that there are special position and orientation of every wheelset that makes the governing equation for computation of the common normal degenerate. This condition leads to divergence of the Newton’s iterate. To develop a procedure that can successfully compute the common normal between a straight rail and a wheelset, first parametric equation for the rail and wheel surface in track coordinate system is developed. Then four nonlinear equations whose solution is location of common normal are constructed. Three of the equations are used to eliminate three unknown in fourth equation. The resulting equation has only one unknown. A hybrid procedure based on Newton method and bisection method is used to solve the roots of the last equation. The utility of this approach is demonstrated by reporting the common normal for a pair of wheel and rail surface at singular position.