A spatial geometry approach to variable cross-section rail modeling: Application to switches and turnouts

Contact between the wheel and rail can have a significant effect on the dynamics of vehicle/track interaction models. Many existing rail surface models rely on curve based geometry which may lead to some geometric inaccuracy in the case of variable cross-section rails. This investigation will focus on the development of a new spatial geometry based rail surface description which reduces this geometric inaccuracy. It has been shown in literature that certain CAD geometry types, such as BSpline curves and surfaces, may be converted to equivalent absolute nodal coordinate formulation (ANCF) finite elements without a loss of geometric accuracy. To this end, a new ANCF surface description of variable cross-section rails is developed. This investigation also demonstrates the feasibility of using, in the future, 3D surface scanning techniques as well as profile curve measurements to develop a rail surface geometry model using the new ANCF surface which can be systematically integrated with complex multibody system (MBS) models. A realistic railroad vehicle example of a turnout, which includes variable cross-section rails, is tested for the case of the new ANCF surface. A study of the numerical results reveals the benefits of using the ANCF surface geometry developed in this investigation.