1、Liu Xintian,Hung Hu ,Wang Jichang,Zhao Lihui,Gao Hui,WangYansongAbstract-Front double wishbone Independent suspension is built according to hard point parameters of a car. After the rubber bushing stiffness of lower control arm is changedThe suspension performance is analyzed and discussed with mult
2、ibody dynamic and Suspension Kinematics theory. The conclusion can be drawn as follows:when wheels are hoping, All the stiffness of lower control arm have no effect on camber angle,caster angle and kingpin_incl_angle,and torsion stiffness of rubber bushing has heavy effect on toe angle,but axial,rad
3、ial stiffness have no effect ,While steering,all the stiffness of lower control arm rubber bushing have no effect on camber angle and toe angle,torsion stiffness has affects on camber angle ,axial stiffness has a little and radial stiffness has heavy , axial and torsion stiffness have none on kingpi
4、n_ incl _angle,but radial stiffness has heavyDuring the analyze of traction force and brake force ,torsion stiffness of lower control arm rubber bushing has no effect on camber angle, kingpin_ incl_ angle and toe angle , axial stiffness has a little, and radial stiffness heavy , According to the cur
5、ve of caster angle VS brake force, radial and axial stiffness of rubber bushing have a little affects on caster angle, but torsion stiffness noneKeywords-Front Double Wishbone Independent Suspension, rubber bushing, stiffnessI. INTRODUCTIONDouble wishbone independent suspension is widely used on aut
6、omobile now. Two wishbones have equal length or not. Equal length of double wishbone independent suspension is Not usually used now , Unequal length of double wishbone independent suspension can keep good road ability and reduce the interference between suspension and steer bar ,with reasonable stru
7、ctural parameters and Proper arrangements to make the parameter of wheel spin and wheel location floating in Permissible range. therefore, it is widely used in front suspension of car and small truck. Front double wishbone independent suspension is regard as research object using multibody dynamics
8、and Suspension Kinematics theory to analyze and discus the influence of suspension performance by axial , torsion , radical stiffness of rubber bushing. II THE MODEL OF THE MULTIBODY DYNAMICSMultibody dynamics theory is the subject that study on the movement rule of the object in system . It is comp
9、osed of multi_rigid_body dynamics and multi_fexible_body dynamics:Where q, , are systems system position,speed,acceleration vector, is langrange multiplier, t R denote the time , M denote inertia matrix of mechanical system, deonte constraint jaclbian matrix, Q denote outside force vector , denote l
10、ocation constraint equation.;Where v(q,t) is speed right side, is accleration right side.Initial condition q(0)= (0)= Putting the initial condition into(2)and (3), the rigid movement can be calculated by above functionsIII FRONT DOUBLE WISHBONE INDEPENDENT SUSPENSION MODELFigure 1, front double wish
11、bone independent suspension modelAccording to the suspension key hard point value of a certain car,front double wishbone independent suspension Kinematics model is built as shown Figure 1 .The characteristics of location parameters are analyzed in some operating conditions. During the analysis, axia
12、l ,torsion, radical stiffness of rubber bushing is respectively increasing to 5 times of original, and then comparison and analysis with the original.IV THE INFLUENCE OF WHEEL LOCATION PARAMETERS BY LOWER CONTROL ARM FRONT BUSHING STIFFNESSWhen front rubber bushing stiffness of lower control arm is
13、changed,the influence of wheel location parameters are discussed separately under the conditions of wheel hop, steering, traction force and braking force.A. Wheel hopCamber angle VS wheel travelCaster angle VS wheel travelKingpin_incl_angle VS Wheel travelToe angle VS Wheel travelFigure 2.The curve
14、of rubber bushing stiffness of lower control arm, wheel location parameters and wheel travel.In fig 2, the four curves are under the conditions of unchanging lower control arm rubber bushing stiffness and radial,axial,torsion stiffness increasing 5 times(the changes of lower control arm rubber bushi
15、ng stiffness are also like this in fig.3,4 and 5). In fig.2 while wheels is hoping ,according to the curve of camber angle vs wheel travel , caster angle vs wheel travel and kingpin_incl_angle vs wheel travel ,the conclusion is drawn that radial ,axial and torsion stiffness of rubber bushing has no the toe angle ,Radical stiffness of rubber bushing has heavy on the toe angle, but axial and torision stiffness have a little from the curve of toe angle vs wheel travel.B Steering analyzeCamber angle VS Steering angleCaster angle VS Stee
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