Dynamic Assessment of Freight Rail Vehicles Passing Through a Jog Aperiodic Irregularity

Abstract

Many factors may cause accidents with rail vehicles. The main ones are related with the vehicle-load dynamics, rundown tracks and unsafe operations. In order to evaluate the railway vehicle dynamics, a multibody system was implemented to model a railway boxcar with 24 DOFs. Based on the system’s excitation, the vehicle behavior can be evaluated in several operating conditions, and the dynamic system is solved with the Runge-Kutta method for numerical integration. When comparing results from a known model to the ones from the developed program, Dynamic Analysis of Railroad Cars (DARC), a consistent correlation is found. When passing over a jog type aperiodic irregularity, the boxcar of 100 t suffers a vertical acceleration of the car body equivalent to 0.38g and thus lowers load on the wheels for an instant. Hence, it is possible to conclude that this irregularity is severe. Considering that AAR establishes a minimum value of 10% of load over the wheel for traffic conditions, the obtained results show there would not be derailment, as the minimum load obtained on the wheel is of 44% in relation to the static load value.