A Study Of Driver Injury Risk Based On Reconstructions Of Passenger Car-to-Tree Accident

In-depth accident investigation with accident reconstruction is an important approach for acquisition of the background knowledge of vehicle safety improvement. Validity and injury evaluations of simulation models and researches on injury mechanisms are also largely dependent on the results of accident investigation and reconstruction. Recently more and more attentions have been paid to the in-depth accident investigation.The current paper is to study the kinematics response of driver and cause of injuries in accident collisions. An example of car-to-tree accident was reconstructed based on in-depth accident investigation by using multi-body (MB) and finite element (FE) method. A systematic method for analysis of drive injury risks was put forward. Furthermore, a parameter study was performed for investigation of the effect on the reconstruction results. The methods advanced provide a way of evaluating and analyzing the protective effect of vehicle to occupants in real accident, simultaneously, occupant injuries in accident can be studied by using the way presented in this paper.The total kinematic course of a car-to-tree accident from GIDAS (German In-Depth Accident Study) was recurred by using PC-Crash program, from which initial impact velocity (V), impact angle (A) and impact overlap (O) were obtained.Finite element simulation was employed to perform the second reconstruction. The finite element vehicle model derived from NCAC (National Crash Analysis Center) which is similar with the accident vehicle. According to test results from literature, a simulation of 100% car to rigid wall impact test with the same impact conditions was performed to validate the reliability of finite element car model. The results of finite element reconstruction were evaluated by comparing the deformation of car damages in terms of velocity, equivalent energy speed (EES) and deformation energy. A design method using orthogonal arrays is exploited to select test points. Optimizing by considering design variables of initial impact velocity (V), impact angle (A) and impact overlap (O) to objective function and constraint conditions were performed to get the best simulation result comparable with accident records.Initial boundary conditions of MADYMO injury reconstruction were defined according to the acceleration impulse of left B-pillar and the rotational angle time history of point near driver seat. MADYMO injury reconstruction model contains three parts:vehicle model, restraints system model (seat belts and airbag) and occupant model. According to output of physical injury parameters from MADYMO reconstruction, evaluation of driver injury risks was conducted based on human injury tolerances which include head linear acceleration, HIC value, neck shear and tension force, neck bend moment, thorax compression, VC, compression force on tibia and femur, tibia index (TI) and contact forces on lower and upper extremities.Design parameters of seat, instrument panel, seat belts and airbag affect a lot on occupant kinematics and injury severity during collision. Studies on sensibility of the change of these parameters to injury severity were performed. Suggestions on special data collection for occupant injury reconstruction from on-site accident investigation were put forward.The study results indicate that the kinematics and injury risk evaluation of driver can well reconstructed by using multi-body and finite element method, by which protective effect of vehicle to occupant in real accidents can be evaluated effectively. Further studies can be done by using human finite element model to understand human tissue biomechanical response in real collisions based on injury reconstructions. The results of parameter analysis on driver restraint system can be used as a reference to vehicle safety design.