Study of rear impact in light trucks and potential injuries to the occupants

Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.According to National Highway Traffic Safety Administration (NHTSA), each year about 400,000 trucks are involved in motor vehicle crashes. Eighteen percent of these accidents are in rear-end crashes of the trucks. Accordingly, fatal injury had resulted to 5 percentages of the injuries. Whiplash is the common neck injury in rear impact consuming billions of dollars in insurance. However due to relatively low number of deaths or injuries in rear impact crashes, NHTSA does not conduct any rear impact testing to test the bumpers. The main objective of this thesis is to study the effects of low speed impact on light trucks and the potential injuries on the occupants. The Federal Motor Vehicle Safety Standards (FMVSS) includes rear impact testing of fuel leakage, but only has a voluntary test for rear bumper impact test at low speed. In this thesis, the low speed rear impact simulation of a light truck was performed to understand the bumper deformation. A Chevy light truck is impacted to a flat barrier at 5 mph by using the finite element code LS-Dyna. This simulation is analyzed and validated for its bumper impact test. A parametric study is thus performed to quantify the effect of various parameters on the rear end impact of the truck. Four vehicles were selected from public domain National crash analysis center (NCAC). These vehicles were Geo Metro, Chevy Truck, Ford Taurus and Ford single unit truck, selected according to the weight of the vehicles. The Chevy truck was chosen as target vehicle and other three models were selected as bullet vehicles. The target vehicle was then impacted with speed of 5, 10 and 15 mph. The accelerations were extracted from the center of gravity of the target vehicle (Chevy Truck). The acceleration pulses from the LS-Dyna were used in multi body analysis Mathematical Dynamic Model (Madymo). The seat model was built with similar characteristics as the Chevy truck seat. A Hybrid ΙΙΙ dummy model was positioned with seat and the model was given the acceleration pulses from the corresponding g’s at low speed for the truck impacted at 5, 10 and 15 mph. This model was used to study the injuries on the neck. The developed model was then compared for neck response from the occupant with head restraint and without head restraint. Output of the dummy response resulted in injury values needed to be studied. The injury values were compared with standard critical values complying with injuries. The result of this study can be utilized to obtain the effect of weight of impacting vehicles in low speed rear crashes of trucks. The impact response of the occupants and potential neck loads and injuries are also by products of this stud