Modeling And Ride Comfort Simulation Of A FF Car Based On Virtual Prototyping Technology

Automotive ride comfort is one of the major performances of modern high-speed andhigh-performance vehicles. With the improvement of living standards，people have higherprospect for ride comfort. However according to a survey, there are still a variety ofproblems involve in ride comfort. Therefore, with the increasingly fierce marketcompetition，the introduction of new technologies and new methods to improve vehiclecomfort become an important way to improve competitiveness. Virtual prototypingtechnology combining advanced modeling, simulation technology, modern informationtechnology, advanced design and manufacturing technology and modern managementtechniques which can be used in vehicle development，testing，analysis and evaluation willgreatly shorten the development cycle，reduce development costs and improve productcompetitiveness in the market. This article based on a FF（front engine front drive）sedanmodel provided by enterprises，can be built in ADAMS/Driveline, with which simulationanalysis can be carried out. Thesis main points are as follows:(1) The thesis discusses the layout features of the FF vehicle，points out the lacks of buildinga FF model and the necessity of building the FF model with ADAMS software.(2) The full-vehicle dynamic model consists of front and rear suspension, tires, steeringsystem, body and powertrain system which includes engine, clutch, transmission, differentialand main reducer. Various subsystems and Driveline test-rig combined to create the vehicledynamic model. This process highlights the connection and communication between variouscomponents.(3) The full-vehicle dynamic model is built in two different kinds of software. The followinganalysis are carried out: a constant torque of the engine, slope torque, torque based on enginecharacteristic curve, impulse torque, step torque and engine torque changing with the throttleby them. By contrast of engine output torque, engine speed, transmission output torque,speed, traction force of driving wheel, longitudinal velocity and longitudinal acceleration ofADAMS and Carsim of the very same condition，the rationality and accuracy of thefull-vehicle model can be confirmed.(4) According to GB/T4970-2009Testing method for vehicle ride comfort, ride comfortsimulation analysis can be conducted. First of all, the basic theory of harmonic superpositionmethod is discussed, and then the random road property file is programmed with MATLAB, at last the correctness and feasibility of the theory of harmonic superposition method can beverified by comparison with standard road spectrum. In the paper，the root-mean-squarevalue of longitudinal acceleration, suspension deflections, tire dynamic load are selected toevaluate the ride comfort of random uneven road and the maximum vertical absoluteacceleration value of body is chosen as the evaluating indicator of impulse input. Finally，with the dynamic model and road file created， simulation is conducted inADAMS/Driveline，by comparison with data of original road file，it is verified that the roadproperty file is correct.