Research On Handling Stability For Semi-trailer Tractor With Air Suspension

With the accelerating pace of modern life，It is high demand for logistics speed.As one of the main bearer of transporting goods, in order to meet the requirements,the semi-trailer tractor’s load capacity and design speed are improving. Runningcontinuously at high speed and heavy loading, if the tractor can’t well follow thecommand of the driver or can’t effectively resist outside interference and to maintainstable driving, it will be likely to cause serious harm to people’s lives and property.Semi-trailer tractor’s handling and stability performance are increasingly subject tothe attention of manufacturers and research institutions.Advanced technologies of modern automobile are generally applied to passengercars first, and then used in other models. Multi-body dynamics analysis has manyapplications in the development of passenger car, but is still in its infancy in thedevelopment of commercial vehicle. This paper is completed based on a cooperationproject with a commercial vehicle company. the project developes a6X4semi-trailertractor with air suspension. A vehicle dynamics analysis model is built by using ofmulti-body dynamics and finite element method, which includes the flexible body ofthe leaf spring, leaf—air compound suspension system, air bag suspension of cab,chassis and accessories, tires, and so on. The model parameters are obtained throughexperiments with the assistance of the corporate. To ensure it’s accuracy, the paperverifies and adjusts the model according to the tests which include the front and rearsuspension stiffness tests, unladen and full load tests, tire test,air bag test and so on.Then the tractor and semi-trailer model are built which can do stability experimentsreplacing the real vehicle.Leaf—air compound suspension system stiffness and leaf spring stiffness have adecisive influence on vehicle performance. Based on the GB "Controllability andstability test procedure for automobiles", the paper analyzes and evaluates thetractor’s handling stability by using the dynamic model. It contains four tests such asthe steady static circular test, returnability test, pylon course slalom test and steeringwheel angle pulse input test. No-load tractor shows good handling and stabilityperformance.Generally, semi-trailer tractor is overloaded driving with semi-trailer, the trailerhas a great impact on driving performance. For security reasons, most handling andstability testing of real tractor are carried out without trailers, a lot of literature is also only limited to the unladen tractor. In order to study the effect of semi-trailer onhandling and stability performance of tractor, the paper carries out the handling andstability simulation with the established vehicle model including semi-trailer, thencompares the results curve and scores with unladen vehicle model. The results showthat the semi-trailer worsen the handling and stability performance of the tractor, inparticular, affect the performance of steady static circular test. According to theresults of the analysis, the paper studies the trend of semi-trailer wheelbase and masscenter parameters effect on the performance of the steady static circular test. itprovides a high reference value on the tractor design and the matching of semi-trailer.