4569846498

178 Multibody Systems Approach to Vehicle Dynamics
Camber angle (deg)
4.0
3.0
Rigid joints
2.0
Linear bushes
Non-linear bushes
1.0
Test data
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
80.0 40.0 0.0 40.0 80.0
100.0 60.0 20.0 20.0 60.0
Bump movement (mm)
120.0
100.0
Fig. 4.38
Front suspension – camber angle with bump movement
Castor angle (deg)
7.0
6.0
5.0
4.0
3.0
2.0
Rigid joints
Linear bushes
Non-linear bushes
1.0
0.0
80.0 40.0 0.0 40.0
100.0 60.0 20.0 20.0
Bump movement (mm)
Fig. 4.39
60.0
80.0 120.0
100.0
Front suspension – castor angle with bump movement
Examination of the results shown here indicate that despite the alignment
of the bushes on the lower arm assembly the calculated suspension characteristics
agree well for models using rigid joints, linear bushes or nonlinear
bushes. It is noticeable with the front suspension that the plots begin
to deviate when approaching the full bump or full rebound positions. This
is due to contact with the bump stop or rebound stop generating forces that
are then reacted back through the suspension to the bushes. The reaction
forces at the bushes leads to distortions that produce the changes in suspension
geometry as shown in the plots. This effect is not present in the
models using rigid joints that have zero degrees of freedom. Geometry
changes are entirely dependent on the position and orientation of the joints.