A Research On Drivers' Injury Biomechanics And Countermeasures In Vehicle Oblique Impact

Vehicle crash safety is more and more important in the field of vehicle engineering. According to the statistics, the ratio of frontal impact in all kinds of vehicle crash accidents is 16%, oblique impact is about 23%. The report of traffic accidents in China in 2005 showed that frontal impact accidents account for 26.43% in all of the accidents, the casualty induced by which accounts for 27.73% of total. As full frontal impact tests could not be used for sufficiently evaluating the injury mode caused by vehicle body deformation, it is necessary to combine it with offset impact and oblique impact to fully evaluate vehicle frontal impact performance.The thesis aims to research the drivers'dynamics response and injury mechanics in oblique impact by using 30°oblique impact FE simulation of a car in market and present some countermeasures against oblique crash. Some options including structure modification and local stiffness improvement are applied in the car model to reduce drivers'injury and could be helpful to the research of vehicle oblique crash.The thesis sums up the 6 common types of oblique impact mode, finds out that 30°oblique impact could cause the severest injury. It also summarizes the injury biomechanics basic theory of drivers'head, neck, chest and lower extremity in oblique impact.Oblique impact FE model was set up by using 50% Hybrid III dummy validated briefly, a trolley sled and a front longitudinal beam FE model and simulated using LS-DYNA to analyze the influence of impact angles on crash pulse and dummy upper extremity injury.By using 50% Hybrid III dummy model, the whole vehicle oblique impact is simulated according to US frontal impact regulation FMVSS 208. Being compared frontal impact output curves with NCAC test result, firstly the Ford Taurus FE model was validated, then the 30°oblique impact model was set up by combining dummy model and vehicle model (no airbag) and simulated. In the same way frontal impact and 15°,45°oblique impact are simulated and the results are analyzed including vehicle body acceleration, deformation and dummy injuries. The analysis showed that lower extremity is likely to suffer severer injury than other parts in oblique impact rather than in other types of impact because the passenger compartment would suffer more intrusion in oblique impact.Some local structures and stiffness of the model were improved against the disadvantage of the whole vehicle model on protecting dummy lower extremity. The frontal structure of the tunnel are strengthened using high strength panels, the stiffness of seat cross member was improved;Sub frame was weakened in some certain areas to optimize the stiffness configuration between energy absorbing zone and passenger compartment and the transferring path to reduce intrusion. More simulation result showed that the improvement had not influence on the impact severity but intrusion in foot area reduced a lot, upper leg force reduced more than 30%,torsion reduction of left and right ankle are 40% and 71%, injury risk of lower extremity reduced greatly. The countermeasures are positive theoretically.