Experimental and Numerical Study of Rollover Crashworthiness of a Coach Body Section 2012-01-1900

The good mobility and large carrying capacity promote the popularity of intercity coach in mass transit, especially in the long distance passenger transport nowadays. However, accidents related to coach and bus usually involve large casualties. Higher risk of fatalities is exhibited in rollover than the other coach accident types. In order to protect the occupants when a rollover accident occurs, coach structure must have sufficient strength to resist the impact loads. This paper presents a rollover test of an intercity coach body section using both numerical simulation and experimental testing to investigate its rollover crashworthiness in accordance with ECE R66. A full scale coach body section is manufactured and a tilting bench is designed and fabricated. Displacement transducers and accelerometer are equipped to record the time history of superstructure deformation and impact acceleration. And the FE model was developed accordingly. Coupon tests were carried out to get the properties of the materials used in the body section. Rollover test is simulated using a nonlinear and explicit code, LS-DYNA. Good agreement is observed between the results from the experimental test and the numerical simulation in terms of the dynamic deformation and impact acceleration, which indicates that the numerical model is validated against the experiment model. Deformation of the superstructure is primarily attributed to plastic hinges in the areas where the side wall pillars and the cross-members are connected. Local buckling behaviors that are unfavourable for loads transmit are found in the cantrails, indicating that the cantrails need to be enhanced. In-depth analysis of the results from simulation and experimental test leads to several design guidelines for coach rollover safety. With the numerical model that is validated by the experimental test, optimization can be performed to improve the structural deficiency exhibited in rollover test.