Basics of Vehicle Dynamics

V e h ic le D y n a m ic s N o t e s

- s h ir n a n d a B h a v ik a t t i

1 . I n t r o d u c t io n
V e h ic le d y n a m ic s is t h e
s tu d y o f f o r c e s a n d m o m e n t s
a c t i n g o n t h e v e h i c le w h e n it is
in m o ti o n
A c c o r d in g t o S A E n o t a tio n s
t h e v e h i c le m o t io n c o - o r d in a t e s
a r e d e f in e d a s s h o w n i n f ig u r e .

, Where
N, Y, 2 are longitudinal, lateral
and vertical directions
of motion of vehicle
respectively.
Mx, My,Mz are the moments about
21412 axes respectively.

In vehicle dynamics, the effects
of all these forces and moments,
on the vehicle behaviour are studied.
The forces and the moments
which are acting on the vehicle,
are generated in the tire and road
contact patch; when the vehicle
is driven in longitudinal and
lateral direction on the different

,types of road.
Hence this study widely divided
into
- study of time, which generates
these forces and moments in
the road and tire contact patch.

- study of longitudinal behaviour
of vehicle when the vehicle is
accelerated or applied brakes.

- study of lateral behaviour
of vehicle when it is changing
the direction or negotiating the
curve/ turn.
- study of vertical motion of
the vehicle when it is passing
over the bumb or pot holes or
undulated road surface

, - The longitudinal behaviour of
the vehicle assists in the study
of performance of the vehicle
during traction (driving) and

braking.
- The lateral behaviour of
vehicle assists in the study
of characteristic and handling
of the vehicle.

- The vertical behaviour of
the vehicle determines the
ride quality, comfort and
road holding nature of the
vehicle.