A Study On Vehicle Secondary Crashworthy Structure And Occupant Injury Protection In Side Impact

Side impact is one of the more common forms in vehicle traffic accidents, the frequency of side impact and numbers of injuries in side impact is the greatest than other types of accidents. It seems that the side structure of vehicle body is relatively weak in stiffness and strength compared to other structures. There are fewer components used to absorb energy and the space is not enough, and the probability of occupant injury is larger than other types of crashes. Therefore, improving the vehicle safety in side impact and minimizing the occupant injuries maximally become important research in vehicle safety. The regulation "Occupant Protection in Side Impact" was developed by China Automotive Technology&Research Center, which has been brought into effect in July1st2006, and Chinese New Car Assessment Program (C-NCAP) was also issued according to foreign experience at the same time.The aim of the present thesis is to improve the side structure of the vehicle and optimize design parameters of the corresponding structure basing on the whole car model verified already, and the paper provides some countermeasures to improve the vehicle safety in side impact and protect the occupants and validate their effectiveness theoretically.Firstly, the paper outlines two basic theories in vehicle impact simulation, and then MDB finite model was developed and validated. By using computational simulation method, the whole car model was developed basing on a certain domestic vehicle model, which was validated by comparing it with the requirements of rules and test data. According to GB20071-2006rules, side impact simulation was done. For the large deformation of the seat in simulation, the stiffness of the seat was adjusted by adding reinforcement in the seat back, increasing the thicknesses of seat parts, changing the materials properties, and then analysis the validity of the improvement of the seat to low the velocity of the B pillar and the front door. Again, Prescribed Structure Motion (PSM) model was developed using MADYMO software to analysis the occupant injuries, also validated the effectiveness of the improvement of the seat from occupant injuries area. At last, By optimizing the design parameters of inner panel of the B pillar and inner panel of the front door by using the orthogonal experimental design (OED) and the Response Surface Method (RSM) methods, and the substitute model based on response surface was developed, and the minimum value of abdominal peak force (APF) was figured out from the subsitute model by using the optimize software ISIGHT. The results of this study indicate that the velocity calculated at point on B-pillar is lowed by42%, and the the velocity calculated at point on the front door is also reduced by36%. The injury values of the Rib Deflection Criterion (RDC), Abdominal Peak Force (APF) and Pubic Symphysis Peak Force (PSPF) are also ruduced correspondingly, and the value of the PSPF is lowed by25%which meets the allowed maximum in standard. At last, the value of the PSPF is4.102kN calculated from the substitute model which is smaller by29%than the primal value. The simulation results showed their positive effects theoretically and that they are strictly helpful on improving the vehicle side impact performance.