1.2 Cornering
Similar phenomena occur on tight
cornering as occur on full braking. In the steadystate phase of cornering, the
loading area is inclined laterally by a rolling angle. A rapid buildup in centrifugal
force up to its maximum value gives rise to a rolling oscillation with
amplitudes which are superimposed on the steadystate rolling angle. The
transverse force parallel to the loading area acting on the cargo is therefore
made up of:
 centrifugal force component from cornering,
 downhill force arising from the geodetic
inclination of the loading area,
 inertial force arising from tangential
acceleration from a rolling oscillation.
In this case too, the normal force acting
from the cargo on the loading area is reduced by two causes, namely, as a
result of the inclination of the loading area, by the
 upwardly directed vertical component of the
centrifugal force of cornering,
 reduced normal component of the weightforce.
Figure
3: Cornering with unfavorable inclination b of the road
Unlike in the longitudinal direction, the
centrifugal force is oriented horizontally in the geodetic reference system,
i.e. not parallel to the inclination of the road. Thus the inclination of the
road has a direct impact on the centrifugal force components through the
downhill force.
Figure 4: Cornering on a level road with
0.42 g centrifugal acceleration and 0.54
g maximum transverse acceleration, maximum rolling amplitude = 5.8°.
Figure 4 shows the numerical solution of
the equations of motion over a period of 6 seconds. The forces acting on the
cargo have been converted into units of g.
Maximum centrifugal acceleration was
deliberately selected at 0.42 g such that, once the rolling oscillations have
subsided, a steadystate transverse acceleration of 0.50 g is established. As a
consequence, the first rolling amplitude gives rise to a maximum transverse
acceleration of 0.54 g. This value increases if the buildup time is shortened
or damping of the rolling oscillations is reduced.
Further simulated cornering maneuvers
with other loading area spring constants and with favorable and unfavorable
corner inclination of the road reveal comparable profiles. The following
general conclusions may be drawn::
 The generally accepted assumption of transverse acceleration of 0.5
g for dimensioning cargo securing against sideways sliding must not be
interpreted in such a way that this value could be solely attributable to the
centrifugal force. Instead, between 20 and 30% of this value must be reserved
for the downhill force from the inclination of the loading area and the
tangential forces from superimposed rolling oscillations.
 In steadystate cornering, the inclination of the loading area is
still present even after the rolling oscillations have subsided and contributes
just about 20% to transverse acceleration.
 The transverse force allowances from the downhill
force and tangential forces have nothing to do with the "rolling
factor", which is required in VDI Guideline 2700 Sheet 2. The rolling
factor takes account of dynamic tipping moments, while the stated allowances
are forces acting at the center of gravity.
 In favorably constructed curves (road inclined
towards the center point of the curve), the parallel component of the force of
gravity is partially offset by the inclination of the road. The opposite
applies when the road is inclined unfavorably.
 As previously with full braking, stiffer loading
area suspension gives rise to smaller rolling angles and the transverse forces
thus approximate to pure centrifugal forces.
 Starting to corner more slowly with buildup
times of distinctly more than two seconds allows the superimposed rolling
oscillations to become insignificant if damping is adequate, because the
initial amplitudes fall within the range of the still increasing centrifugal
force.
 The normal force from a given cargo unit is
reduced by an order of magnitude of around 5%. This has a negative impact both
on friction and on stableness.
