Some of the material in is restricted to members of the community. By logging in, you may be able to gain additional access to certain collections or items. If you have questions about access or logging in, please use the form on the Contact Page.
While rollover crashes are the least frequent types of crash, around one third of vehicle occupant fatalities occurs in rollover crashes. Rollover crashes are usually associated with multiple impacts which result in complex interactions between occupants and a passenger compartment. Compared to the numerous experimental and computational studies on the rollover in passenger cars, efforts on bus rollover safety are far lagging behind. Based on a literature review, available studies on a bus rollover safety have mainly focused on structural integrity rather than considering occupant responses in their assessment. However, detailed information about the characteristics of occupant responses is lacking. Additionally, to design the effective occupant protection systems and safety evaluation tools, understanding the vehicle-occupant interaction is essential. There have been A few field data studies that provide some insights into occupant injuries (e.g., severity and distribution of injuries) using post-crash data, however, their results show a qualitative assessment rather than a quantitative assessment of occupant kinematics and injury risk. The main goal of this research was to characterize the vehicle and occupant responses during the rollover crash using both experimental and numerical methods. Two different experimental rollover tests include a modified dolly rollover (MDR) and tilt table (TT) tests were conducted using a similar bus and anthropomorphic test device (ATD) configurations to understand the effects of vehicle kinematics on occupant injuries. In each test, a 2-point and 3-point belted 50th percent male Hybrid III ATDs were used and the injury risks were measured for different parts of body. Next, two different computational models were developed to further understand the effects of test parameters and structural performance on injury outcomes. The full-scale finite element (FE) model of the bus were simulated in LS-DYNA and validated against experimental data. Because, the Hybrid III was originally designed for frontal crashes, the FE model of the EuroSID-2re, which his developed for the side impact crashes, was also implemented. Then, a series of FE simulations were conducted, and the structural deformation and occupant injury risk were quantified. Lastly, to obtain the more realistic characteristics of bus rollover crashes, the real-world rollover accidents were simulated using the multibody dynamic (MBD) model of the bus in PC-Crash software. An application of the combined MBD and FE simulations has been presented to and the results of the two crash tests were compared with the results of accident reconstruction. The results of this study showed that the most common impact mechanism among these rollover scenarios is the impact between the bus’s cantrail (roof connection to the sidewall) and ground that caused similar lateral deformation patterns. Also, unlike the passenger cars where the vertical roof deformation can significantly increase the occupant injuries, the intrusion of the bus passenger compartment was not identified as a source of any major injury. Furthermore, The highest head, neck, and chest injury risk were predicted during the MDR simulation where the ATD was partially ejected through the shattered side window. The findings of this research can benefit automakers who seek to improve the effectiveness of structural safety systems of the bus and regulatory agencies seeking to develop the vehicle tests targeting the safety of the passengers in the bus rollover crashes.