Modeling, Handling And Stability Analyzing & Evaluating Of A A-Class Vehicle

The topic was raised under the background of the lack of the core technology of the vehicle chassis.Through studying and researching abroad advanced vehicle chassis technology,rich the database of the vehicle chassis development,and enhance our capabilities of self-deve- lopment and innovation,and improve vehicle design and development pr- ocess system,and provide valuable experience and the basis for self- development.In this paper,based on the theory of multi-body system dynamics, multi-body system dynamics template of the rear suspension is built in the mechanical system simulation software,ADAMS/CAR,and the temp- lates of the front suspension,the front suspension horizontal stabi- lizer,the powertrain system,the braking system,the steering syste- m,the body and the tire already exist in ADAMS/CAR and are changed in order to satisfy our needs.The subsystems based on the templates are established,and the full-vehicle dynamic model is built.According to the national controllability and stability test procedure for autom- obiles,the full-vehicle dynamic model of the vehicle is simulated,analyzed and evaluated.In this paper,the specific work as follows:1.Establish the Full-Vehicle Dynamics Model of the vehicle The multi-link rear suspension of the vehicle is not the Macpherson suspension nor the traditional multi-link suspension, which featuresthe integration of a variety of suspension.Because ADAMS/CAR still is not ready template in its structure,it needs to be established.In template builder interface of ADAMS/CAR,the rear suspension template was established.First,the structure is simplified. According to the Simplified structure,establish Hardpoints coordinates and Construc- tion Frames.Build various general parts and Mounts the rear suspension of the vehicle from Hardpoints coordinates and construction.Then establish Forces,including Damper,Spring,Bumpstop.And establish Joints,Bushi- ngs and Communicators,which are used to exchange information between the rear suspension and the subframe etc.Finally,by adjusting the model until the model is reasonable,the ultimate template of the rear sus- pension of the vehicle has been completed.Other templates of the full-vehicle dynamics model of the vehicle include: the front suspension template,the front suspension horizontal stab- ilizer template,the powertrain template,the braking system template, the steering system template,the body template and the tire template. These templates are available in ADAMS/CAR,in addition to doing some structural modification of the front suspension,Other templates on their Hardpoints,and documents of attributes and parameters to make the necessary changes to obtain the required templates.According to the front suspension template,the rear suspension template,the front suspension horizontal stabilizer template,the po- wertrain template,the braking system template,the steering system template,the body template and the tire template,the subsystems are established in standard interface of ADAMS/CAR.Finally,by adjusting the model until the model is reasonable,the ultimate full-vehicle dynamics model of the vehicle has been completed.2.Simulation,Analysis and Evaluation of the Full-Vehicle Dynamics Model of the vehicleAccording to the requirements of the current standards GB/T6323.1 -94~GB/6323.6-94 of the national controllability and stability test procedure for automobiles,carried out simulation and analyses for ve-hicle handling stability,such as steering wheel angle step input test procedure,steering wheel angle pulse input test procedure,pylon course slalom test procedure,steering efforts test procedure,returnability test procedure and steady static circular test procedure.In each si- mulation test the road condition is entirely consistent with《Road Test Method General Clauses for automobiles》;Parameters and road conditions are entirely consistent with《Controllability and Stability Test Procedure for Automobiles》;Made the program of Data Processing according to《Controllability and Stability Test Procedure for Automobiles》;And made the program of evaluation the car's handling stability performance by scoring according to GB/T 13047-91《Criterion Thresholds and Evaluation of Controllability and Stability for Automobiles》.In conclusion,the multi-body system dynamics software-ADAMS is a powerful and efficient approach in the research of vehicle dynamics. Along with the constant development of vehicle dynamics and computer technology,the dynamic simulation technology will play a greater role in the development of automobile chassis.