Vehicle Dynamics Simulation Study By Virtual Prototype Technology

In recent years, traffic accidents occurred frequently, and they made seriousthreat to people’s life. Among accidents which caused casualties, rollover accidentsaccounted for a large proportion. Statistical data from the NHTSA shows that SUVshave higher possibility of rollover accidents than other types of cars and cause agreater loss. Therefore, it is significant to study the effect of the anti-rollhydraulically interconnected suspension (HIS) on the automobile dynamics.This thesis is based on the project of National Natural Science Fund of ChinaProject "Anti-Rollover Control Study of Active Hydraulic InterconnectedSuspension of Vehicle (Project No.51175157)”. With the purpose of studying theeffects of the anti-roll hydraulically interconnected suspension on vehicle handlingstability and ride comfort, this paper firstly introduces the background, history andcurrent study status of the hydraulically interconnected suspension, makes adetailed description of the structure and working principle of the anti-rollhydraulically interconnected suspension.Then the subsystems of the SUV are established with the ADAMS/CAR basedon the datas, such as moment of inertia of the body got from the test and otherknown parameters. Modal natural frequencys of the bounce, pitch and roll modalare obtained by doing vehicle frequency response analysis with the assembled fullcar model to verify the accuracy of the established vehicle model.After verifying the accuracy of vehicle model, simulation analysis are didrespectively with the standard SUV model and the SUV model equipped with theanti-roll HIS under the conditions such as steering wheel angle step input, steeringwheel angle pulse input, random uneven road excitation, unilateral bump incentive,to compare the difference of roll angle, yaw rate, lateral acceleration, verticalacceleration response of these two SUVs under these conditions. Simulation resultsshow that anti-rollover capacity of the SUV quipped with the anti-roll HIS has beensignificantly improved while its ride comfort has not been impacted almostly.Finally, the influence of variation of the structure parameters of the HIS on theequivalent independent suspension stiffness and damping of roll and bounce modeis analyzed. The half-car model of a SUV fitted with anti-rolling HIS system isestablished in the domain of frequency, the expressions of equivalent independent stiffness and damping of the system are derived, the method to get the equivalentindependent suspension stiffness and damping with suspension system parametersis found. And then simulations are carried on to analyze the influence of variationof cross-sectional area of the hydraulic cylinder chamber, the inner diameter of thehydraulic pipeline, the pre-charge pressure of accumulator on the equivalentindependent suspension stiffness and damping of roll and bounce mode. Resultsshow that hydraulic components parameters variation of the anti-rolling HISsystem has a great influence on equivalent independent suspension stiffness anddamping of the roll mode, but a little on the equivalent independent suspensionstiffness of the bounce mode. This analysis provides the reliable theory basis forthe optimization design of the HIS system.