Research On The Modeling And Simulation Of Full Vehicle Based On Multi-body Dynamics

In the past40years, the capability of high precision simulation of such a complex ehicle system has been greatly enhanced rapidly, while the multi-body system dynamics heory provides a strong support for the complex mechanical systems in modeling, structural lesign, analysis and optimization. This made a wide range of applications in vehicle lynamics. In this paper, the modeling of a multibody system of vehicle using the recursive (?)gorithm is presented. The multi-body program is implemented, And the dynamic simulation s performed. The topology of multi-body dynamic system has been analyzed, decomposed (?)nd glued by a new method, the gluing algorithm and the numerical simulation has been mplemented. Then using the virtual prototyping software ADAMS/Car, the vehicle system (?)as been assembled after the modeling of the front suspension module, the rear suspension nodule, steering, body and the powertrain module. The vehicle handling stability and ride (?)mfort have been predicted and analysed as well as the optimization of the front suspension (?)lignment parameters.The content is as following.Firstly, on the basis of the analysis of a variety of multi-body dynamics modeling nethod, a multi-rigid-body model of vehicle has been established using the recursive (?)lgorithm. In order to facilitate research, the overall vehicle structure has been simplified appropriately. On these basis, the vehicle topology has been analysed, a spanning tree opology of the system is obtained by cut joints that open the closed loops in the multi-body system. On one hand,17cut joint constraint equations, Jacobi Matrix, the velocity and acceleration equations have been derived. On the other hand,23equations of the motion of (?)he system has been formulated; The Magic Formula tire has been modelled. Later, the model of the Magic Formula tire as external program of vehicle multi-body system has been embedded into the vehicle simulation; The differential-algebraic equations have been solved (?)sing augmented method and constraint stabilization is performed using direct method. The nulti-body program is implemented using MATLAB program. The simulation including vehicle acceleration, deceleration, pulse input and step steer input has been performed. The gluing algorithm for multi-body dynamic system has been discussed. And the triple pendulums system has been simulated and the quadruple pendulums system which has elastic parts has (?)een simulated by the gluing algorithm. The modeling and simulation of the vehicle has been given. The results show the availability and the validity of the gluing algorithm. It is showed that the the method is simple and has a high accuracy, it is also easy to be implemented in computer when using the multi-body dynamics. Meanwhile, the kinematic and dynamic characteristics of vehicle is well presented and got, therefore, it is a effective tool for the research of vehicle dynamics.Secondly, The front and rear suspension, steering, body, powertrain and brake system module have been established using the virtual prototype simulation software ADAMS/Car and therefore, a more accurate multi-body model of vehicle is built; The simulation of front suspension kinematic has been performed. And the alignment parameters have been optimized using ADAMS/Insight according to the problem found in the simulation results. Finally, the vehicle handling stability and ride comfort have been analysed. The random road profile and3d roof road are built for comfort analysis. The result showed that the vehicle handling and stability performance are still needed to be improved and optimized, while the car performs very well on the stochastic road and roof road.