Simplified Methodology for Ride Comfort Assessment Based on Wheel/Rail Contact Geometry Synthesis

Abstract

This article proposes a simplified methodology for ride comfort assessment based on wheel/rail contact geometry synthesis without Complicated measurements or simulations. A mechanism drawing with particular reference to G(1) continuity is used to describe a reliable wheel/rail profile and to derive a profile equation to be applied in contact geometry synthesis. The proposed method is used to explore all possible positions of contact between a wheel and rail on each side of the track. Based on synthesis results, moving and fixed centrodes of carbody motion are proposed. The degree of smoothness of the moving and fixed centrodes is applied to define the range of the sweet spot in terms of the wheel/rail tread area. In this study, contact between the Shinkansen wheel and UIC60 and JIS60 rails is investigated as a case study. The results show that the Shinkansen wheel matches the UIC60 rail more effectively because it has a wider range of contact sweet spots than the JIS60 rail when rolling stock is running on a curved track. Finally, the Shinkansen wheel profile and each rail profile equation are applied in simulation software of a vehicle track system with different wheel/rail matchings to verify that contact geometry synthesis can be used to assess ride comfort. A dynamic simulation program, whose parameters are adjusted to fit experimental values, is used to compare the results. The results show that both the vertical and lateral vibration acceleration responses of a carbody with the Shinkansen wheel in contact with the UIC60 rail are stable and lower than those for the JIS60 rail. Furthermore, the UIC60 rail provides a better degree of ride comfort to passengers when matched with the Shinkansen wheel. Therefore, contact geometry synthesis of wheel/rail contact can be used to assess the movement behavior of rolling stock and derive a simplified index of ride comfort.