Railway transportation is considered as one of the safest means of transportation. Different kinds of devices have been developed to prevent collision accidents. However, the collision accidents summarized in Appendix point out in the reality at present collision accidents cannot be fully eliminated. As a result, the research on the passive safety of railway vehicles is necessary and important. In this thesis the responses of railway vehicles during a collision accident have been systematically analysed. The main objective is to mitigate the injury severity by means of reasonable measures to prevent the collided vehicles from derailment. The research work has been carried out by using multi-body system (MBS) software SIMPACK. Two collision scenarios from the European Standard EN 15227 have been adopted in this thesis as the designed collision scenarios. According to the analysis of collision accidents it has been pointed out the collision between two freight trains, especially on a curve, deserves to be taken into account. Therefore, this collision scenario has been designed and involved in this thesis. Firstly, the collision simulation between two railway multiple units has been carried out to explore the causes of overriding phenomenon. Computer simulations demonstrate in addition to the initial vertical offset described in EN 15227, vehicle pitching motion has great influence to the overriding collision. This pitching motion is affected by some important factors, such as collision mass, pitching frequency and height of the centre of gravity of car body. Secondary, the derailment of a collided city tram has been analysed. The corner collision scenario defined in EN 15227 has been adopted. Simulation results indicate this collision scenario is mainly focused on the structure deformation and collision energy absorption. Due to the large impact angle (45°), it is unlikely for a city tram to comply with this scenario without derailment. In order to avoid derailment the maximum impact angle has been recommended to decrease to 25°. Besides that, computer simulations demonstrate that there are many contributing factors to the derailment phenomenon of a collided city tram. Compared to the factor of impact point position, the derailment phenomenon is more sensitive to the variations in impact angle, mass of loaded passengers and friction coefficient. Moreover, two measures have been proposed to prevent the collided city tram from derailment. One is using secondary lateral dampers to absorb the collision energy. Another is increasing the lateral stiffness of secondary springs as well as lateral clearance to store the collision energy in the suspension. It has been validated by collision simulation with these measures the safety against derailment can be improved. The third and last part of this thesis focuses on the collision between two freight trains. This collision scenario has been designed occurring on a curve rather than on a tangent line. Therefore, from the point of view of safety against derailment this collision scenario is more critical than the scenarios defined in EN 15227. Two kinds of conventional freight wagons have been chosen and simulated. Moreover, it is pointed out there are many contributory factors to the responses of freight wagons during a collision, such as curve radius, distance between bogie pivots, loading mass, etc. The derailment phenomenon is less likely to occur, when freight trains are collided on the curve with larger radius. Besides that, the characteristics of freight wagons with large axle loads, low centre of gravity of car body and appropriate static strength are favourable for the collided wagons to reduce the risk of derailment.
Derailment investigations of rail vehicles during collision accidents
Untersuchungen zum Entgleisen von Schienenfahrzeugen während Kollisionen
2014
118 Seiten, Bilder, Tabellen, 151 Quellen
Hochschulschrift
Englisch
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