7/27/2019 Vehicle Suspension Model and Dynamic Simulation on Handling Stability

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Vehicle Suspension Model and Dynamic Simulation

on Handling Stability 

Xiaobin Ning,Jishen Sheng,Bin MengDepartment of Mechanical Engineering

Zhejiang University of Technology

Hangzhou, China

nxb@zjut.edu.cn

Jie ZhangTechnical Center 

Wanxiang Group

Hangzhou, China

aerohoser@263.net

 Abstract  —Chassis platform is usually supplied for several types

of cars which has their individual requirement for handling

stability and ride comfort. Therefore the stiffness, damping and

the dimension of the guide mechanism of the suspension have to

be adjusted to meet the different performance requirements of 

different styles of cars. In this paper a module exclusively for

handling stability analysis of chassis platform is developed basedon ADAMS/Car. With this module chassis engineers can easily

adjust the parameters of suspension such as spring stiffness,

damping and hard points location to match the front and rear

suspension suitably and then predict and optimize the

performance of the suspension system. By this approach different

types of cars that using chassis platform can fulfill their own

handling stability.

 Keywords-chassis ; suspension; handing stability;simulation

I.  I NTRODUCTION

Chinese vehicle industry are developing quickly at present,and most of them want to take a transition from “develop car 

 body, borrow foreign mature Chassis” to “develop a chassis platform for cars of different types”, the requirement of chassisassembly system is becoming stronger than any time before

 because the level of the platform of shared chassis becomes asymbol of maturity of car manufacturer. In most internationalcar manufacturers, one of their leading techniques is the chassis

 platform, with which they can develop different types of carsaccording to the analysis of market through adjusting part of the platform, so they can occupy the market quickly and getmore profit. However since Chinese national car manufacturersare short of related technologies and talented person in car engineering, the design and performance evaluation of theshared chassis have not been developed yet. From a

 professional point of view, shared platform refers to the sameset of development techniques which can be applied to cars of different types, so several derived model could bemanufactured from a shared platform. Theoretically it meanscars of different levels could be manufactured from the same

 production line to reduce development costs and to increase productivity.

Chassis platform can derive several types of cars and everytype of car has its own requirement of handling stability, so it’snecessary to find a way of simulating and evaluating handlingstability of derived model quickly. An analysis module

exclusively for analysis of suspension kinematic performanceand chassis platform handling stability is developed usingVC++6.0. The module with menus and dialog boxes for theman-machine interface can easily accomplish the modeling,analysis and optimization of suspension and shared chassis,and automatically complete the extraction, management and

display of the data in the analysis process by calling the multi- body dynamic software ADAMS/Car, so the users can greatlyenhance the design efficiency.

II.  FUNCTIONS AND MAIN INTERFACE OF THE 

MODULE

The module has been developed according to the modeling,simulation, data processing and optimization which arenecessary in the analysis of suspension and shared chassis withVC++6.0 as platform in the windows environment, and it’s

main functions include:Ԙ Automatic parametric subsystem

modeling of the suspension, steering, anti-roll bar, car body

and tires.ԙ

Automatic assembly of the suspension and sharedchassis. Ԛ Easily accomplish the kinematic simulation of 

suspension, postprocessor of the simulating results andextraction of the data. So the users can easily evaluate the

kinematic performance of the suspension.ԛEasily analyze and

evaluate the handling stability of shared chassis, automatically

 process the simulating results and extract the data. ԜEasily

optimize the suspension and chassis whose kinematic performance and handling stability is not good.

The main interface has been developed with VC++6.0 asshown in Fig 1. The main interface can call every dialog whichwill automatically read the input parameters and open theADAMS/Car to accomplish all the functions introduced above.

This study used a chassis platform from the WanxiangGroup as an example. Firstly the parametric model of front,rear suspension and chassis is built; then the kinematic

 performance of the front, rear suspension is analyzed; at lastthe chassis to two types of cars and carried out the simulationof handling stability is applied to verify the practicality of themodule.

978-1-4244-7739-5/10/$26.00 ©2010 IEEE

7/27/2019 Vehicle Suspension Model and Dynamic Simulation on Handling Stability

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Fig.1 Main Interface

III.  MODELING AND SIMULATION OF THE 

SUSPENSIONS

 A.   Parametric Modeling of the Macpherson Front 

SuspensionsAccording to the requirement of chassis platform, the

suspensions should be parametric models, so the locations of hard points, stiffness of spring, damping of damper and wheelalignment parameters can be easily adjusted to derive severaltypes of cars.

By using the module, the parametric models of themacpherson front suspensions of the two cars were built in themulti-body dynamic software ADAMS/Car and saved to the

 private database. Fig.2 shows the assembled model of themacpherson front suspensions of the two cars which includingmacpherson suspension subsystem, front anti-roll bar subsystem and steering subsystem.

Fig.2 Assembled Model of the Front Suspensions of B1, C2

In the module, there are two simulating modes of kinematic performance for the suspensions that built above, parallelwheel travel and opposite wheel travel. This study chose thefirst mode, carried out the "parallel wheel travel±50mm"

simulation of the assembled suspensions by using ADAMS/Car.And results of the simulation are shown in Figures 3, 4 and 5.

Fig.3 Camber Angle Curve of Front Tire

Fig.4 Toe Angle Curve of Front Tire

Fig.5 Lateral Displacement of Front Left Tire

From the results we can see that these parameters (camber, toeand tire lateral displacement) are changing reasonably when thetires travel, so the kinematic performances of the frontmacpherson suspensions of the two cars both reach therequirement of handling stability for the chassis. And thekinematic performance of the front suspension belonged to C2is little better than the front suspension belonged to B1.

 B.   Parametric Modeling of the Rear Double Link 

Suspensions

According to the requirement of chassis, the modeling mode

of rear suspension is just like the front suspension. The parametric model of rear suspensions of B1, C2 have been

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 built (shown in the Fig 6) and saved to database by using the

module.

Fig.6 Assembled Model of the Rear Suspensions of B1, C2

Like the front suspension, the "parallel wheel

travel±50mm" simulations were carried out for the rear suspensions of B1, C2. And the results are saved in database.

From the results of the simulation we can see that these

 parameters (camber angle, toe angle and tire lateraldisplacement) of the rear suspensions are changing reasonably

when the tires travel, so the kinematic performances of the

double-link rear suspensions of the two cars both reach therequirement of handling stability for the chassis. And the

kinematic performance of the rear suspension belonged to B1

is little better than the rear suspension belonged to C2.

C.   Modeling and Simulation of B1 & C2

The chassis platform consists of front macpherson

suspension, rear double-link suspension, tires, car body,

steering system, braking system and power system. In order to

verify the adaptation of chassis to different types of cars, two

cars of different types called B1, C2 are chosen as examples.Their parametric models were built by adjusting the locations

of hard points, stiffness, wheelbase, wheeltrack, full quality

and tires of the chassis. Fig.7 shows the assembled model of 

B1, C2 built in ADAMS/Car by using the module. The two

cars have the same type of front, rear suspensions, same FF

engine, same disc brake, and their bodies are simplified to

rigid bodies, their quality are also simplified to centroids

which contain moments of inertia.

Fig.7. Assembled Model of B1, C2

Tableĉ shows the main parameters of B1 and C2.

TABLE I. THE MAIN PARAMETERS OF B1, C2

Main Parameters B1 C2

Full Quality/kg 1579 1845

Front Axle Load/kg 799 849

Rear Axle Load/kg 780 996

Front Wheeltrack/mm 1470 1420

Rear Wheeltrack/mm 1470 1440

Wheelbase/mm 2610 2695

Front SpringStiffness/N·mm-1

24.7 25.1

Rear Spring

Stiffness/N·mm-116.56 16.85

Tires 205/50 R16 185/70 R14

Since steady-state cornering performance is one of the most

important behaviors for handling stability, so it is chose as an

example to test the handling stability of the two cars. The

steps of the steady-state cornering simulation carried out in thestudy refer to the Chinese national standard GB/T 6323.6-

94[7].ķMake the car running along a circle with radius of 15

meters at the lowest stable speed and then fix up the steeringwheel. ĸ Accelerate the car slowly and evenly at a

longitudinal acceleration that less than 0.25m/s2. Ĺ Stop the

simulation when the lateral acceleration reaches to 6.5m/s2.

According to the Chinese national standard, the stead-state

cornering simulations of B1 and C2 were carried out and the

comparative curves of steady-state cornering characters

including 1 2α α − , R/Ro and roll angle of car body are shown

in Figures 8,9 and 10.1 2α α − represents the difference

 between later slip angle of front axes and later slip angle of rear axes, R/Ro represents the ratio of cornering radius in one

moment "R" and initial cornering radius "Ro".

Fig. 8 1 2α α − Curve

Fig.9 R/Ro Curve

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 Fig.10 Roll Angle Curve

 D.   Evaluayion

In accordance with the evaluation criteria of steady-state

cornering in Chinese national standard QC/T 480-1999[8],

evaluation of the steady-state cornering characters of the two

cars has been carried out in the study.

Scoring evaluation of the steady-state cornering characters

is based on 3 evaluating indicators:  nα  (the value of lateral

acceleration at neutral turning point), U (degree of understeer), K ¶(roll-degree of car body). Table 2 shows the values of the 3

indicators of the two cars which can be separately found in

Figures 14 to 16.  nα  is the value of lateral acceleration in the

1 2α α − curve where the slope is zero; U is the value of 

average slope in the 1 2α α − curve where the lateral

acceleration is 2m/s2;  K ¶ is the value of average slope in the

roll angle curve where the lateral acceleration is 2m/s2.

TABLE II. VALUES OF THE 3 I NDICATORS OF B1, C2

Indictors B1 C2

2/na m s−⋅   8.5 8.9

U/ ( ) ( )1

0 2m s−

⋅ ⋅   0.22 0.27

( ) ( )1

0 2/ K m sφ 

−

⋅ ⋅   0.62 0.7

The scoring equation of n

a can be expressed as:

( )60100 60

40

60an n nn n

 N  α α α α = + × −− 

(1) 

Wherean is the scoring value of  n

a ; 100na is the upper 

limit of  na , 100n

a =9.8m/s2; 60na is the lower limit of  n

a ,

60na =5.0m/s2.

Calculation of the equation (1): an (B1)=89; an (C2)=92.5.

The scoring equation of U can be expressed as:

( )( )

( )( )60

100 60 100 100

60 40U 

U U U U   N 

U U U U  

λ 

λ 

− −= + ×

− −  (2)

Where U  is the scoring value of U; 100U  is the upper 

limit of U,100

U  =0.4e/(m•s2);60

U  is the lower limit of U,

60

U  =1.0e/(m•s2); λ  is the coefficient calculated according

to the ratio of 60

U  and100

U  ,

60 100

100

60 100

2 /

( / ) 24

U U U 

U U λ = ×

−=

 

Calculation of the equation (2):u

(B1)=90;U 

(C2)=94.

The scoring equation of  K φ  can be expressed as:

( )60

60 100

4060 N K K 

 K K φ φ φ 

φ φ 

= + × −

−

(3)

Where φ  is the scoring value of  K φ  ;100

 K φ  is the upper 

limit of  K φ  ,o

100 0.7 K φ  = /(m•s2);60

 K φ  is the lower limit of 

 K φ  ,o

601.2 K φ  = /(m•s2).

Calculation of the equation:  N φ  (B1)=100; φ  (C2)=100.

The composite scoring value of B1 and C2 can be derived as:

( ) ( )1 / 3w an U   N H N N N φ = + + = (89+90+100)/3=93 (4)

( ) ( )2 / 3w an U  

 N C N N N φ = + + = (92.5+94+100)/3=95.5 (5)

From the results it can be seen that the composite scoring

values of steady-state cornering characters of the two cars are

 both satisfactory, and the steady-state cornering characters of the two cars are both good. Besides, the scoring value of C2 is

slightly higher than B1, so the steady-state cornering character 

of C2 is better.

IV.  SUMMAR  

In this paper, a module exclusively used for analysis of 

suspension of chassis platform based on vehicle handling

stability was developed with the platform of VC++6.0 and

ADAMS/Car. By using the module, parameterized models of 

the front, rear suspension and the chassis platform were built

in this paper, and kinematic simulations of the front, rear 

suspensions were carried out easily and the results show that

the kinematic performance of the suspensions are both goodenough to reach the requirement of handling stability of 

chassis platform. Then two cars of different type which using

the chassis were taken as an example to do the cornering

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simulation and evaluation, the results show that the steady-

state cornering characters of the two cars are both good. So

 practicality of the module has been verified, and the efficiencyof modeling and analyzing of suspension and chassis platform

is improved with the module.

ACKNOWLEDGMENT

Financial support for this research was provided jointly by

Science and Technology Department of Zhejiang Province

(Grant No.2008C01002) and Zhejiang University of Technology (Grant No.20080174).

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