Stability Simulation In The Car

Automobileisaveryinclusiveinertia,elasticity,dampingandotherdynamicfeaturesofcomplex nonlinearsystems, characterizedbymanylocomotionparts, mechanical complexity.And vehicle's controllability and stability as a high-speed car drive safely decide one of themain performances, are known as the drivers' "high-speed vehicles lifeline." In order toensure safe driving, automobile's controllability and stability have become an increasingemphasisonmanufacturers.Vehicle's controllability and stability are defined as a kind of capacities that in thecondition of the driver does not feel too nervous and fatigue, the vehicle can be set thedirection of traffic by the driver through the steering system and steering wheel, and whenencountered outside interference, the vehicle can resist the interference to maintain thestabilityoftraveling.As commonly considering, vehicle controllability and stability contain two interknittedparts.Oneiscontrollability;theotherisstability.Controllabilityreferstoakindofcapacitiesthat whether automobile can move to the correct direction following the manipulations ofsteering mechanism and the steering wheels. Stabilityrefers to a kind of capacities that withthe conditions of motor vehicles at the outside interference, the vehicle can resist to theinterference and maintain the original direction of travel. Difficult to categorically separatethe two, a direct impact on the stability of the mixed-operated, it is often only knowncollectivelyasthecontrollabilityandstability.This article discusses some of the most basic parts of the vehicles'controllability andstability: the stable response of steering wheel angle under the step input, the transientresponseandthefrequencycharacteristicsoftheyawangularvelocity.The stable and transient response of steering wheel angle under the step input, that is, vehicle controllability and stability characterization of the time-domain response of thesteering wheel angular displacement. Back to positive is a power steering wheel inputtime-domainresponse.The frequency response characteristics of yaw angular velocity, that is, under thesinusoidal input of steering wheel angle, frequency from 0 to∞, the changes of thevehicle's steering wheel angular velocity and yaw angle of amplitude ratio and phasedifference in graphics. It is another important characterization of the basic vehiclecontrollabilityandstabilitycharacteristics.The Vehicle using conditions and using requirements are complex, the research ofcontrollability and stability develops later, up to now it is still not very sophisticated.Therefore, controllability and stability requirements, evaluation indicators and test methodare not unified. The same test in different countries, different factories have differentapproaches.Vehicle is a physical system which is made up of a number of automotive components.Ithasinertia,elasticity,damping,andmanyotherfeaturesofthedynamics,soitisadynamicsystem which is more than one degree of freedom. It should be noted that components thatconstitute a vehicle dynamics system, such as tires, suspension, steering, etc., havenon-linear characteristics. The differential equations describe the vehicles should be anon-linear differential equations, so that the vehicles are nonlinear systems. But in mostdriving conditions, vehicle lateral acceleration does not exceed 0.4g, if overlooked someminorfactors, youcanputvehicleassimilartothelineardynamicsystem.This article is about analysis and discusses on the vehicles as a linear system and inaccordance with the relevant provisions of GB6323-94 "Controllability and stability testprocedure"and GB/T13047-91 "Criterion threshold and evaluation of controllability andstability for automobiles ", the car simulation model is calculated and analyzed on therelevant data. And also on the base of the car simulation model we have processed transientcharacteristics of the steering (the steering wheel angle step) and the steady-statecharacteristics of rotating (accelerating / steering wheel angle step), and shift back to being analyzed.Then, compare the simplified model simulation results with the flexible body modelsimulationresults.Nowtheflexiblebodymodels applyawiderangeofmedicine,machinery,the manufacturing sector. In the automotive field it is mainly used in simulation analysisabout vibration and noise, controllability, stability and drive comfort. Abroad because ofadvanced test and simulation equipment, flexible body models have been refined to therubber parts. Because of the current domestic production and the design have not fullydivorced from the combination, flexible body model just focuses on the now widely usedabroad, indoor air, some entities in body parts and vehicles. It's narrower, and has not yetbeenwidelyused.Finite element mesh building is the process of dividing discrete objects into the simpleunit intheworkingenvironment.Commonlyused simpleunits include: one-dimensional rodelement and lumped mass element, two-dimensional triangle, quadrilateral andthree-dimensional tetrahedron element, pentahedron and hexahedron element. Their bordersmainly have the shapes of beeline, curve and curved surface. For the border for the curve(surface) type of unit, the finite element analysis requires that curve or the surface of eachside has a number of points, so that it can guarantee the form of units, at the same time, canimproveaccuracyandspeeduptheconvergencerate.Thesameobjectofdifferentdimensioncan be divided into grids with a mixture of multi-unit. In this calculation the flexible bodytypethathasbuiltispentahedron.To form flexible bodythere are two ways: first, using the mode results to form flexiblebody, generally it has to reserve the top ten ranks mode in addition to rigid-body mode.Second,addtheresultsof2-3bandsbytheuseofstaticmode.In the finite element model we build the super-unit and retain the external node, that isthe connected points of multi-body model, and also give the necessary reservations modalorder.WeuseMSC.NASTRANtobuild*.outfile,andthenuseADAMS/ FLEXmoduletotransform*.outfileto*.mnffile.Finally, according to People's Republic of China National Standard Test Method for Vehicle Stability we carry through steady-state rotation experiment, shift transient responsetest (step input steering wheel angle), turned back to performance tests on the car cars. Wecarried out dynamic simulation analysis using ADAMS software, compared and analyzedexperimental results and simulation results in order to identify the causes of error, andfurther verified that the accuracy of simulation results are better by adding a flexible bodymodelsimulationarebetterthanthosethatdidnotaddflexiblebodymodel.With the growing development of the national economy, civil living condition is alsoincreasing; people's awareness of the requirements of motor vehicles is not just possessionlevel. With the prices of high-grade motor vehicles falling down, auto car, the highconsumption product, has been civilian; and it is no longer a symbol of luxury. With thegrowing national economy, people's"pocket money"is also on the rise. When people wantto buya car, not onlyeconomic, safety, comfort has also taken into account more and more.With the continuous development of science and technology and domestic production levelscontinue to improve and simulation analysis is also more and more accurate, comfortable orNVHSimulationanalysis is also paidmoreand moreattention,duringwhichtheapplicationofflexiblebodywillalsobeincreasinglymorewidespread.