Optimization And Matching Of Passenger Compartment Subarea Stiffness For Car Side Impact

With the growth of vehicle ownership, road traffic accidents have become a majorsocial problem worldwide. The latest decade of traffic accident statistics show that thetraffic accidents caused by side impact are higher than by frontal crash. And side crashfatality rate run after frontal collision, while of the injury rate side crash comes to thefirst place. As strength of the vehicle side body structure is weaker and the side collisionbuffer is smaller plus a weaker body energy absorption capability, the crew faces ahigher injury risk. Therefore, a research for safety of vehicle side crash has an importantsignificance for improving the overall safety performance of China’s automotiveproducts.The article is based on a self-brand car, research on the optimization of caroccupant compartment stiffness, stiffness matching law in different regions of the sideof the crew compartment and the relationship between subarea stiffness and occupantinjury indicators. The research and conclusions for side impact safety have somereference value. The main work and conclusions are as follows:(1) According as the laws and regulations of the side-impact in China，This paperestablish and validate the finite element model of the MDB for the computer simulationof the side impact according as the distortion characteristic and absorbing energy of theMDB. Finally it is proved that the MDB model can be used for research of the computersimulation of the side impact.(2) We establish a more complete crash simulation of finite element model for sideimpact including the car body, engine, gearbox, suspension systems, wheel assembly,rigid wall, the electric motor, fuel tank and battery etc. At the end, we build a side crashsimulation. As to several aspects of energy and mass conservation situation of thevehicle movement, speed changes, and body deformation, we do a detailed analysis ofcomputer simulation results and make an objective evaluation. The rib distortion of driver is35.45mm, and the chest score is only1.31.this results prove that the safety performance ofvehicle is so bad that it should be improved on and optimized.(3) This paper divides the body side impact area into six regions for researching thecrew compartment side of the partition stiffness level. In addition, it analyses theimproving potential of the partition stiffness. Results show that the stiffness of bodysides showing up to down weak to strong trend. Then we obtain the key factors affecting the stiffness of the crew compartment and lay the foundation for the next occupantcompartment stiffness optimization and matching such as B-pillar、the crashworthy poleand so on.(4) In order to enhance the optimization efficiency, this paper do the research of thepredigest model about the side impact. Using orthogonal experiment method and thesimplified model and vehicle model simulation analysis comes to the optimizationprogram to meet the side crashworthiness requirements. This results prove that B-pillarintrusive velocity of the first and second optimization programs decrease respectively0.91m/s、1.93m/s. The top B-pillar intrusive displacement decrease respectively9.92mm、26.18mm；The mid B-pillar intrusive displacement decrease respectively31.01mm、69.99mm；The bottom B-pillar intrusive displacement decrease respectively30.33mm、78.9mm；The improving effects prove obvious and improve the safetyperformance of vehicle.(5) Based on the optimization we research for the crew compartment side of thepartition of the stiffness characteristics. We get partition stiffness matching law and therelationship between the partition stiffness and occupant injury indicators. And in thecase of not involving the dummy, we forecast and project occupant’s chest scores. It isshown that the subarea stiffness of the six regions merges two group: high stiffness leveland low stiffness level. The shape of each stiffness curve likes mountain profile which ishigher in the middle, and lower on both sides. The peak stiffness is120N/mm higherthan ravine’s for the high stiffness curve and30N/mm for the low stiffness curve. Thepeak stiffness for the high stiffness curve is approximately150N/mm higher than thepeak’s for the low stiffness curve. It is shown that the stiffness curve is increasedsynchronous on the improvement of side crashworthiness, and the relationship betweenthe occupant thorax score and the peak stiffness value can be calculated. The studyprovides a significant reference for the research of side impact safety.