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Liquid cargo has a significant impact on the interface wheel-track interaction. The sloshing affects the track-railcar's dynamic behavior. The effect is detectable at the track level and at the vehicle. Its characterization requires the combination of different techniques:
Empirical Mode Decomposition (EMD)
Time-Frequency Maps
Sloshing occurred when significant perturbations happened in the railcar:
The railcar entered a curve
Reduction in its travel speed
A railcar with a tank is a clear example of a multibody dynamic system with a nonlinear behavior.
This paper presents the study of the impact caused by a liquid Cargo on a railway infrastructure. The dynamic behavior of a tank car corresponds to a multibody dynamic system with several degrees of freedom. This study’s data were obtained from a scale experimental fixture consisting of a track and a railcar with a tank. The track was instrumented with strain gauges and the railcar with accelerometers. The data showed non-periodic and periodic terms; therefore, the results were analyzed with the Empirical Mode Decomposition method (EMD).
It was found that the EMD identified the signal components that were related to the sloshing. These components represent the mode shapes of the original signal.
The location of the sloshing in the track was found applying spectrograms to the accelerometer data. This paper’s experimental outputs suggest that the sloshing effect is detectable at the track and in the vehicle dynamics.
The efficiency and safety of railway transportation depend both on numerous factors linked to the vehicle, the infrastructure, the operator and the environment. Curved tracks are subjected to demanding situations due to elevated stress levels, as a function of the operating conditions and vehicle/infrastructure design. In such segments, steering forces are superimposed to lateral load transfers. The steering forces depend on the condition and the design of the centre plate and bogies’ suspensions design. While the friction at the centre plate provides the needed damping to mitigate the hunting vibration of the bogie in straight track segments, such yaw resistance originates high steering forces and rail damage on curved tracks. A centre plate with low friction at turns and high friction at straight track segments would thus be highly advantageous. In this paper, a centre plate design is proposed which provides a yaw-rotation resistance torque that depends on the bogie-car relative position. Two different designs are considered for that purpose, one that combines a spring-acted centring mechanism with a lower pair kinematics, while the other one involves higher kinematic pairs which should incorporate lateral damping elements. As a result of using an engineering design approach, the higher kinematic pairs-based design is recommended however, the validation of such operational principles, including the introduction of the needed damping, should be configured on the basis of experimental models.
Wheel forces generate stresses in the rail as a function of several vehicle and infrastructure characteristics and operating conditions. The different components of the wheel forces develop strains in the rail which contain an elastic and hysteretic (irreversible) components. The irreversible deformations of the rail would be associated with locomotive energy losses. In this paper, a testing facility is proposed to indirectly characterize the level of stresses in the rail, in terms of the energy that is lost during tuming maneuvers. Different potentially influential factors are considered, including the friction at the Center plate, the wheelbase length, the distance between bogies and the radius of the curved track. The change
in the potential energy during a U-turn displacement is measured. In this respect, an experimental model under this operating principle, aimed at validating such a principle of Operation, reveals a significant effect of the friction at the center plate on the energy lost during turning maneuvers, and consequently, on the level of stresses in the rail.
Exposure of pressure vessels to fire can result in catastrophic explosion and escalation of accidents. The safe transportation of cargo in pressure vessels therefore requires knowledge of what will happen to the cargo in the event of a vehicle derailment or rollover resulting in fire exposure. The chapter presents an overview of selected testing and modelling work undertaken to understand the thermohydraulic processes within a vessel that drive pressurization during fire. A series of experiments highlighting the importance of adequate design and selection of protection systems are summarized. It is concluded that pressure relief alone is typically insufficient to prevent vessel rupture, but the combination of relief and thermal coatings can be effective.
Turning maneuvers originate higher forces exerted on the rail and the loss of locomotive energy, at a rate that is function of several parameters that influence the magnitude of the developed horizontal wheel-rail forces, including the friction at the centre plate and the bogie´s yaw stiffness. However, such a friction at the contact surfaces of the centre plate is needed to mitigate the Hunting phenomenon when the train moves on straight track segments. In this paper, a self-centering centre plate is proposed, consisting of a lubricated centre plate, equipped with a spring- and damper-based self-centering mechanism. Simulation results of the proposed mechanism suggest that the energy performance in turns of a train car equipped with such self-centering centre plate is comparatively better, as the peak friction forces linked to the dry friction at the contact surfaces of current centre plate designs, are avoided. The assessment of the hunting performance of the proposed device in straight track segments is proposed as the continuation of this work.
A facility is proposed in this paper to apply a selective carburizing process to the lateral faces of a railways´ head, aiming to increase its carbon content and to decrease the friction coefficient in case that the flange of the railway car wheel gets in contact with the rail during turning. Such a treatment would reduce the energy that is lost during the turning maneuvers performed by the vehicle, further improving the energy efficiency of the railway car. The facility consists of a furnace, which should be set next to the rails´ hot-rolling facility, in order to use the available enthalpy. The proposed furnace is equipped with what is necessary to avoid the decarbonization of the remaining rail material, based upon batteries of oxy-acetylene burners that are installed at the bottom of the furnace, on the opposite side to the carburizing surface. An experimental facility is necessary to validate the operational principles for the equipment proposed in this paper. On the other hand, a study should also be carried out to assess the effect of any rail welding process on the carburized surfaces.