The Construction Of Vehicle Suspension Simulation Analysis And Development Platform

Suspension system is one of the most important assemblies of vehicle and its characteristics directly affect the comfortableness, maneuverability and the travel security of vehicle. Road roughness that has a direct impact on the major traveling performance of vehicle is one of the main excitation sources of automobile vibration. During the simulation analysis of vehicle which makes use of its simulation model to imitate the actual driving conditions, how to gain the road information to accurately reflect the actual road, how to establish a rational road input model and how to factually reconstruct the three-dimensional virtual road model have been the key issue of simulation.The integrated development of suspension system is a complicated system engineering and involved in many fields of subjects and technologies, such as the experiment, database, CAD/CAE, kinematical and dynamic analysis of multi-body system,optimization algorithm and software engineering. In order to improve the design quality of the suspension system and shorten the development cycle as well as lower manufacturing cost, the key technologies related suspension are researched in this paper aim to construct the vehicle suspension simulation analysis and development platform. The main contents and contributions of the paper are summarized as follows:At present, commonly used McPherson and double-wishbone suspensions have been integrated in the kinematics analysis system of the platform. The matching design of vehicle toe-in and camber can be realized and the structure and geometric parameters of the suspension mechanism's simulation models can be rapidly and conveniently edited by using the fast parameterized design function module of the system. By calling RecurDyn solver, the kinematics simulation and analysis function module of the system can get the simulation results. The software system's correctness was verified by comparing the simulation results with ADAMS. The simulation results can be inspected by using the ZedGraph control, which is integrated in the function module. Taking the minimum variation of the front wheel alignment parameters and the minimum lateral displacement of the tires as the optimal object, the optimization function module of suspension's the structural parameters is constructed based on genetic algorithm. The validity of the optimum method was verified by comparing the simulation results of initial design and optimum design. The optimization results showed that the coordinates of the McPherson suspension swing arm's front and rear points have effect on the changes curve of front wheel alignment parameters as well as lateral displacement of the tires to the run out of automotive wheels.The dynamic simulation system of heavy truck suspension with main and auxiliary spring was constructed based on based on a 2-DOF virtual prototype model of quarter vehicle. The principal design parameters of the model can be conveniently edited and the time-domain road roughness model can be generated which based on the harmony superposition method and its information was imposed on the virtual prototype model to create a translation motion. Taking account of the minimum of the root-mean-square value of vibration acceleration on suspended mass as objective function, the genetic algorithm was applied to optimize the suspension's damping value, stiffness ratio and critical load ratio of the main and auxiliary spring. The optimization results showed that this method is better than the mean proportional method and the average load method with regard to suspension system with main and auxiliary spring.Based on studying the AR model, the contrastive analysis of parameter estimation algorithms of L-D and Burg model have been done. The results showed that the two algorithms have essentially the same effection as the parameters of the AR model of time series are estimated but the algorithm of Burg model outperforms L-D model in precision.The reconstruction of 2-D AR model was simplified by means of converting the 2-D double auto-variable AR model into two single dependant variable models and separating 2-D low frequency signals through 1-D low pass filtering twice in the direction of ? and v.The road roughness reconstruction system based on AR model adopts wavelet transformation method to filter the measured data and can output the road file of RecurDyn and ADAMS.Based on the concept of two leaves spring model equivalent simulation multi-leaf spring model, the multi-body dynamics model of leaf spring in term of discrete beam method was built in RecurDyn. The contact and friction force between the interacting spring leafs has been effectively imitated by defining the user subroutine translational forces so that the dynamics model can reconcile both stiffness characteristics and hysteretic properties of leaf spring. DOE study showed that the thickness coefficient of beam element, elastic modulus, shear modulus and damping ratio have the most effect on stiffness characteristics and hysteretic properties of leaf spring. Based on genetic algorithm, the developed application program can make effective identification of the parameters of the two leaf spring dynamics model and make the model reflect the characteristics of leaf spring more veritably. The contrastive analysis of meta-model optimization algorithm and genetic algorithm have been done. The results showed that the meta-model algorithm outperforms genetic algorithm in efficiency, but the latter outperforms the former in precision.The full vehicle model of a van has been built in RecurDyn which consist of front suspension, rear suspension, cab and other subsystems. The ride comfort of the van transporter physical prototype has been tested. Simulating results agreed well with the experimental data which verified correctness of full vehicle model. DOE method was used to analyze the influence of suspension parameters and cab suspension parameters on the ride comfort, which provides the basis for the selection of the range of variables. The full vehicle model has been optimized and revised to improve its ride comfort. In the optimization process, the minimum of total weighted acceleration RMS of the driver's foot floor has been chosen as the objective function and the stiffness and damper of the front suspension, the stiffness of rear suspension, the stiffness and damper of cab suspension have been chosen as design variables. For the convenience of viewing the simulation results and parameters optimization, the van comfort analysis system has been developed which consist of simulation analysis and parameters optimization modules.A method which based on the integrated product model of suspension has been proposed to ensure the consistency of the platform data and the corresponding organizational model and product model have been built. The integration method of genetic algorithm in the platform has been discussed and the three necessary conditions for genetic algorithm to meet the multi-body dynamics software have been proposed.Moreover, five multi-body system dynamics optimization algorithms have been researched comparatively.