Analysis Of Vehicle Rollover-stability Under Unstable-state Turning Condition

Vehicle rollover is regarded as one of the highest risking traffic accidents,and the injury level it leads to is only after vehicle collision in single car accidents and its incidence is remained stubbornly high in multivariable car accidents.Therefore,domestic and foreign auto manufacturers and research institutions attach more importance on vehicle rollover.Recently,the sales of Sport Utility Vehicles increase rapidly.Comparing with ordinary cars,the SUV’s CG is relatively higher,which shows that the urgent avoidance and swerve of SUV can easily cause vehicle rollover accidents.The parameter to evaluate the probability of vehicle rollover is named as vehicle rollover-stability index.It can be applied to provide reference to estimate vehicle rollover.So its universal applicability and reliability is quite crucial.The tests of vehicle dynamic rollover are widely used.It laid vigorous standards on vehicle condition,test field and the test contents,but the actual driving process of vehicles is much different from test process.Therefore,it is very necessary to research rollover stability according to actual road driving.The thesis comes from the National Natural Science Foundation of China “AntiRollover Control Study of Active Interconnected Suspension of Vehicle”(Project No.51175157),and it mainly consists of the following parts:1.By using dynamic modeling methods,it explicitly deduced and built a 10-DOF vehicle maneuvering-rollover model which considered the impact of vehicle longitudinal motion on vehicle rolling.Based on all test standard conditions of rollover stability,it tested real cars’ rollover stability and the final results proved the validity of the model.2.Considering the limitation of current rollover stability assessing index,a new rollover stability evaluation method was creatively put forward based on energy approach.Moreover,an energy stability index of vehicle rollover was fully deduced.Under the same condition,the validity of energy approach is proved by comparing with the current methods.Due to the contains: vehicle velocity,roll angle velocity,roll angle and tire steering angle,the energy approach can be applicable even under some special conditions when the current method is invalid.3.In order to avoid the excessive conditions of vehicle tests and to effectively simulate the rollover-stability of real vehicle steering,a series of unstable-state condition were built.The 10-DOF vehicle model and energy approach are applied to study the vehicle rollover-stability,and the effects that the unstable-state conditions act on vehicle rollover were found.By completing the works above gradually,a full vehicle maneuvering-rollover model was built,the energy approach was proposed and applied,the effects and regulars that the unstable-state conditions act on vehicle rollover was summarized.