Simplified Modeling Of Vehicle And Ride Comfort Analysis In Virtual Proving Ground

Ride comfort of vehicle is mainly to maintain the influence of vibration and impact environment on occupant comfort in the course of driving within a certain limit.It is one of the main performances for modern high-speed vehicles.Long-term exposure to vibration not only causes physical fatigue of passengers,but also causes various diseases.In addition,ride comfort also affects vehicle handling stability and power.Improving ride comfort is conducive to driving safety,protecting the health of passengers and improving the comprehensive performance of automobiles.In view of the limitation for traditional theory and test methods,virtual simulation technology has become an important method for ride comfort analysis of vehicle.Virtual Proving Ground(VPG)has become a software widely used in ride comfort analysis because of its systematic and comprehensive advantages.At present,the detailed finite element model of the body is mostly used in the simulation model of the virtual proving ground,who has many elements and degrees of freedom,leading to a long analysis and design cycle.Aiming at the above problem,this paper uses the frame model of body to carry out simulation analysis and research of ride comfort.The frame model has the advantages of simple structure,few elements and degrees of freedom,high accuracy,and can greatly shorten the simulation analysis time of ride comfort.It is suitable for rapid analysis and design of automobile in the conceptual design process.Firstly,the three-degree-of-freedom dynamic model of a quarter car is used to deduce the analytical formula of the driver's RMS acceleration response under road random excitation.The influence of vehicle dynamic parameters on driver's RMS acceleration is studied by analysing the formulas.Then,the expression of optimal damping ratio of driver's buffer system is obtained,and the influence of each parameter on the optimal damping ratio is analyzed.The detailed finite element model of the body-in-white is reduced to the frame model,and the accuracy of the simplified model is verified.The accuracy of the model can reach more than 80%.Secondly,the detailed finite element model and the frame model of the car body are used to build the vehicle model combined with the database of VPG software.Then the simulation analysis of ride comfort is carried out by using the two vehicle models.The error is less than 16% comparing the simulation results of the two models.The rationality and validity of the vehicle model built with frame model are verified.The calculation time of the frame model is only about 5% of the detailed finite element model,which greatly improves the efficiency of simulation analysis.Next,the influence of suspension spring stiffness,shock absorber damping and driving speed on ride comfort of the vehicle is studied by adjusting parameters up and down.Finally,the BIW-Frame is developed by secondary development based on Hypermesh,which realizes rapid modeling of frame model for body-in-white.It not only guarantees the accuracy of modeling,but also improves the efficiency of modeling.The functions of the software are divided into four parts: pre-processing,beam creation,joint creation and post-processing.