Calculation of the shrinking contact resistance by truncated cone model to simulate the contact of armature and rails

The shrinking contact resistance is due to the current shrinking near the so called “a-spot” contact area between conductors. In the numerical simulation of armature and rails, e.g., in the finite element simulation, such “a-spot” model can not be dealt with, since the gaps between conductors are too narrow to be meshed. It is suggested in this paper that a circular truncated cone can be employed to simulate the “a-spot”. The truncated cones with suitable dimensions is able to enlarge the gaps wide enough to be meshed, and simulate the contact resistance in a desired accuracy. The method of determining the suitable dimensions of truncated cone is given based on the calculation and analysis of the resistance of truncated cone with different dimensions. With the truncated cone models, the finite element method can be implemented to deal with the partly contact between the armature and the rails, and acceptable simulation accuracy can be gained.