Study On The Derailment Mechanism Of The Vehicle Based On Catastrophe Theory

The safety of the railway transportation is the prime condition in the process of train running in orbit. Vehicle derailment is the most important factor that endangers the running safety of trains. With the continuous development of the heavy-load and high-speed railways, it makes the problem of the running safety in the railway transportation particularly outstanding. The derailment of train will caused a heavy and great loss to people’s life and property, and it would also cause more serious negative social influences, especially the derailment of heavy-load or high-speed train would bring a devastating catastrophe. For many years almost all railway exports、administrations and technical personnel has done a lot of things in the railway research, great achievements has been made in the theoretical analysis and experimental research about the mechanism of derailment. However the derailment of train is a complex mechanical process, involves many factors, and is very difficult to be described only by given a perfect fixed formula. Research shows that currently using the Nadal derailment coefficients and reduction rate of wheel load to evaluate and analyze the derailment have certain uncertainty and considerable limitations. Therefore, based on thorough understanding of the derailment mechanism and the currently using derailment evaluation criterion, to seek a more reasonable evaluation criteria reducing even avoiding the derailment of train accident is very necessary. With the mathematics thought-catastrophe theory has been proposed, in some ways catastrophe theory provides a new idea for the research of derailment mechanism.Based on the detailed overview of present derailment mechanism research at home and abroad, this thesis summarizes and provides the currently using derailment evaluation criterions and their defect. With the help of elementary catastrophe theory which has been extensively studied and analysed, based on catastrophe theory, the cusp catastrophe model of the derailment accident is established. And also the catastrophe characteristics of the model have been analyzed and described. Combined with the cusp catastrophe model of the derailment accident, the bifurcation set of the catastrophe model has been analyzed, and in that model two factors:the derailment coefficient and the angle of attack, which would impact the derailment of train have been considered comprehensively. In this paper a new evaluation method which is based on the hazardous area of the train derailment has been proposed. By using the simpack dynamics simulation software, the vehicle dynamic model has been set up. The derailment coefficients and the attack angle of the vehicle dynamic model has been calculated in different speed rating, and the distribution of them has also been analyzed. With the help of the vehicle dynamic model, the qualitative analysis of catastrophe model has been tested and verified through examples. By reference to the dynamic model of a single wheelset, the cusp catastrophe model of a single wheelset derailment has been established. Combined with the parameters of a wheelset, this paper evaluates the catastrophe stability of the model.