Course stability analysis for towing system of a gravity-based structure in managed ice fields

Author(s):  
Yue Han ◽  
Li Zhou ◽  
Shifeng Ding ◽  
Meng Zhang ◽  
Yanmin Guan
1986 ◽  
Vol 30 (02) ◽  
pp. 136-146 ◽  
Author(s):  
Michael M. Bernitsas ◽  
Nikos S. Kekridis

The course stability of a towed vessel is traditionally assessed using local linear analysis of a time-independent system of a ship towed by an inelastic towline. In this work a method is developed for studying the global stability of a nonlinear time-dependent model of the horizontal plane motions of a ship towed by a nonlinear elastic rope. First, the critical points of the corresponding autonomous system are found in the phase space and their nature is determined by local analysis. Then the global behavior of the trajectories in the phase space is predicted on the basis of the local analysis results. The results of the stability analysis are verified by comparison with the solution of the model by simulation. A barge, a tanker and a Mariner, with markedly different course stability characteristics, towed by two different elastic ropes are used to illustrate the method.


Author(s):  
Denys Popelysh ◽  
Yurii Seluk ◽  
Sergyi Tomchuk

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.


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