Development and validation of a general vehicle dynamics simulation (NUCARS)

NUCARS (New and Untried Car Analytic Regime Simulation) is a general-purpose program for modeling rail vehicle transient and steady-state response. NUCARS models the interaction of an arbitrary number of rigid or flexible bodies joined by suspension-element-type connections. Means are provided for varying the number and identity of the degrees of freedom chosen for each body. The potential choices include all translational and rotational body degrees of freedom and the first flexible modes (for all bodies, excluding the wheelsets) in twist and in vertical and lateral bending. All connections must be assigned a stiffness and/or damping characteristic. Rigid connections are given large stiffnesses. The representation of connection location and of forces through the connections is chosen to minimize the program memory required. NUCARS is coded in Fortran 77 for use on IBM-compatible personal computers. Three vehicle dynamics applications are presented, including results of validation testing with a lightweight, two-axle, intermodal car.