Audi A8 2019 Service Training page 13

Roll hemming
Roll hemming is used all around for the entire front and
rear door sills. This process increases the door opening area
(better ingress and egress for the occupants) and improves
the field of vision in the A-pillar area.
Roll hemming
Carbon fiber rear bulkhead
An ultra high strength, torsion-resistant rear bulkhead
made of carbon fiber is the largest component of the occu-
pant cell and accounts for 33 per cent of the torsional
rigidity of the overall vehicle. To fully absorb the loads in
the longitudinal or transverse direction and shear forces,
6 to 19 fiber layers are placed on top of one another for
load optimization. These individual fiber layers are com-
posed of 1.96 in (50 mm) wide bands which can be posi-
tioned individually at any fiber angle and with a minimum
cut to create a finished layer.
Load application direction
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B-pillar
Roll hemming is complemented by grip punch riveting
which fixes the side wall frame in its position. This is in
addition to all around structural bonding. These joining
techniques allow the aluminum side wall frame to be
mated with the hot-worked, ultra high strength sheet steel
of the B-pillar, roof arch and sill with narrow flanges.
Grip punch rivet
The carbon fiber rear bulkhead, which contains all attach-
ment points for components such as the loudspeakers, the
rear sunshade, the three-point safety belts and the rear
center armrest, is inserted into the body through the rear
window cutout during final assembly. It is connected to the
body structure using two-component strength adhesive
and rivets. The two-component adhesive prevents contact
corrosion.
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