2024年4月12日发(作者：)

外文文献（二）

外文原文

Abstract： To improve the suspension performance and steering stability of light

vehicles, we built a kinematic simulation model of a whole independent

double-wishbone suspension system by using ADAMS software, created random

excitations of the test platforms of respectively the left and the right wheels according to

actual running conditions of a vehicle, and explored the changing patterns of the

kinematic characteristic parameters in the process of suspension motion. The

irrationality of the suspension guiding mechanism design was pointed out through

simulation and analysis, and the existent problems of the guiding mechanism were

optimized and calculated. The results show that all the front-wheel alignment parameters,

including the camber, the toe, the caster and the inclination, only slightly change within

corresponding allowable ranges in design before and after optimization. The

optimization reduces the variation of the wheel-center distance from 47.01 mm to a

change of 8.28 mm within the allowable range of -10 mm to 10 mm, promising an

improvement of the vehicle steering stability. The optimization also confines the

front-wheel sideways slippage to a much smaller change of 2.23 mm; this helps to

greatly reduce the wear of tires and assure the straight running stability of the vehicle.

Keywords： vehicle suspension; vehicle steering; riding qualities; independent

double-wishbone suspension; kinematic characteristic parameter; wheel-center distance;

front-wheel sideways slippage

1 Introduction

The function of a suspension system in a vehicle is to transmit all forces and moments

exerted on the wheels to the girder frame of the vehicle, smooth the impact passing from the

road surface to the vehicle body and damp the impact-caused vibration of the load carrying

system. There are many different structures of vehicle suspension, of which the independent

double-wishbone suspension is most extensively used. An independent double-wishbone

suspension system is usually a group of space RSSR (revolute joint - spherical joint -spherical

joint - revolute joint) four-bar linkage mechanisms. Its kinematic relations are complicated, its

kinematic visualization is poor, and performance analysis is very difficult. Thus, rational

settings of the position parameters of the guiding mechanism are crucial to assuring good

performance of the independent double-wishbone suspension. The kinematic characteristics

of suspension directly influence the service performance of the vehicle, especially steering

stability, ride comfort, turning ease, and tire life.

In this paper, we used ADAMS software to build a kinematic analysis model of an

independent double-wishbone suspension, and used the model to calculate and optimize the

kinematic characteristic parameters of the suspension mechanism. The optimization results are

helpful for improving the kinematic performance of suspension.

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2 Modeling independent double-wishbone suspension

The performance of a suspension system is reflected by the changes of wheel alignment

parameters when the wheels jump. Those changes should be kept within rational ranges to

assure the designed vehicle running performance. Considering the symmetry of the left and

right wheels of a vehicle, it is appropriate to study only the left or the right half of the

suspension system to understand the entire mechanism, excluding the variation of WCD

(wheel center distance). We established a model of the left half of an independent

double-wishbone suspension system as shown in Figure 1.

3 Kinematic simulation analysis of suspension model

Considering the maximum jump height of the front wheel, we positioned the drives on

the translational joints between the ground and the test platform, and imposed random

displacement excitations on the wheels to simulate the operating conditions of a vehicle

running on an uneven road surface.

The measured road-roughness data of the left and right wheels were converted into the

relationship between time and road roughness at a certain vehicle speed. The spline function

CUBSPL in ADAMS was used to fit and generate displacement-time history curves of

excitation. The simulation results of the suspension system before optimization are illustrated

in Figure 2.

The camber angle, the toe angle, the caster angle and the inclination angle change only

slightly within the corresponding designed ranges with the wheel jumping distance. This

indicates an under-steering behavior together with an automatic returnability, good steering

stability and safety in a running process. However, WCD decreases from 1 849.97 mm to 1

896.98 mm and FWSS from 16.48 mm to -6.99 mm, showing remarkable variations of 47.01

mm and 23.47 mm, respectively. Changes so large in WCD and FWSS are adverse to the

steering ease and straight-running stability, and cause quick wear, thus reducing tire life.

For independent suspensions, the variation of WCD causes side deflection of tires and

then impairs steering stability through the lateral force input. Especially when the right and

the left rolling wheels deviate in the same direction, the WCD-caused lateral forces on the

right and the left sides cannot be offset and thus make steering unstable. Therefore, WCD

variation should be kept minimum, and is required in suspension design to be within the

range from -10 mm to 10 mm when wheels jump. It is obvious that the WCD of

non-optimized structure of the suspension system goes beyond this range. The structure needs

modifying to suppress FWSS and the change of WCD with the wheel jumping distance.

ADMAS software is a strong tool for parameter optimization and analysis. It creates a

parameterization model by simulating with different values of model design variables, and

then analyzes the parameterization based on the returned simulation results and the final

optimization calculation of all parameters. During optimization, the program automatically

adjusts design variables to obtain a minimum objective function [8-10]. To reduce tire wear

and improve steering stability, the Table 1 Values of camber angle α , toe angle θ , caster angle γ and

inclination angle β before and after optimization

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