Exploration of Equivalent Design Approaches for Tanks Transporting Flammable Liquids

Tank vehicles are widely used for the road transportation of dangerous goods and especially flammable liquid fuels. Existing gross weight limitations, in such transportations, render the self-weight of the tank structure a crucial parameter of the design. For the design and the construction of metallic tank vehicles carrying dangerous goods, the European Standard EN13094:2015 is applied. This Standard poses a minimum thickness for the shell thickness for the tank construction according to the mechanical properties of the construction material. In the present paper, primarily, the proposed design was investigated and a weight minimization of such a tank vehicle with respect to its structural integrity was performed. As test case, a tank vehicle with a box-shaped cross-section and low gross weight was considered. For the evaluation of the structural integrity of the tank construction, the mechanical analysis software ANSYS ® 2019R1 was used. The boundary values and the suitable computation for structural integrity were applied, as they are defined in the corresponding Standards. The thickness of the construction material was decreased to a minimum, lower than that posed by the standards, indicating that the limit posed by them was by no means boundary in terms of structural integrity.

Computational Evaluation of Stability in Slosh Dynamics of Tank Vehicles Using Zero Moment Point

Sloshing characterized by inertial waves has an adverse effect on the directional dynamics and safety of partially filled tank vehicles, limiting their stability and controllability during steering, accelerating or braking maneuvers. A mathematical description of the transient fluid slosh in a horizontal cylindrical tank should consider the simultaneous lateral, vertical and roll excitations assuming potential flows and a linearized free-surface boundary condition. While the determination of vehicle stability would require coupling this model to a dynamic roll plane model of a tank vehicle resulting in a computationally expensive analysis. Considering the need for a simpler method to predict roll stability for partially filled tank vehicles, we explore the Zero Moment Point of a liquid domain as a novel solution to this challenge. Numerical investigations are carried out in a three-dimensional partially filled tanks while tracking the movement of the liquid-air interface by employing the volume of fluid method in OpenFOAM. The center of Mass and Zero Moment Point were calculated from the computational results using analytical expressions. The movement of free surface is found to be in good agreement with available literature. The center of mass of the liquid domain was traced as a practical means to quantify the slosh in the tanker. The analyses are performed for different fluid fill heights at varying speeds. The results suggest that the roll stability of tank vehicles can be efficiently analyzed using the zero moment point with significantly lower computational effort.

TO THE STABILITY OF TANK VEHICLES IN THE BRAKE MODE

This article discusses the question of the possibility of improving the roll stability of partially filled tank vehicles while braking. We consider the dangers associated with partially filled tank vehicles. We give examples of the severe consequences of road traffic accidents that have occurred with tank vehicles carrying dangerous goods. We conducted an analysis of the dynamic processes of fluid flow in the tank and their influence on the basic parameters of the stability of vehicle. When transporting a partially filled tank due to the comparability of the mass of the empty tank with the mass of the fluid being transported, the dynamic qualities of the vehicle change so that they differ significantly from the dynamic characteristics of other vehicles. Due to large displacements of the center of mass of cargo in the tank there are additional loads that act vehicle and significantly reduce the course stability and the drivability. We consider the dynamics of liquid sloshing in moving containers, and give examples of building a mechanical model of an oscillating fluid in a tank and a mathematical model of a vehicle with a tank. We also considered the method of improving the vehicle’s stability, which is based on the prediction of the moment of action and the nature of the dynamic processes of liquid cargo and the implementation of preventive actions by executive mechanisms. Modern automated control systems (anti-lock brake system, anti-slip control systems, stabilization systems, braking forces distribution systems, floor level systems, etc.) use a certain list of elements for collecting necessary parameters and actuators for their work. This gives the ability to influence the course stability properties without interfering with the design of the vehicle only by making changes to the software of these systems. Keywords: tank vehicle, roll stability, mathematical model, vehicle control systems.