The chin bar of motorcycl
e
full
-
face helmets
is the
most
likely
region
of the helmet to
sustain
impact
s
during accident
s
, with a
large percentage
of these impacts lead
ing
to basilar skull fracture
.
Currently,
helmet chin bars are
designed to mitigate
the peak acceleration at the c
entre
o
f
g
ravity
of
isolated
headforms
, as required by standards, but they are not designed to mitigate
the neck force, which is
probably the cau
se of
basilar skull fracture,
a type of head injury that can lead to fatalities
. Here we test
whether
it is possible to increase the protection of helmet chin bars while meeting standard requirements.
Fibre
-
reinforced composite shells are commonly used in
helmets due to their lightweight and energy
absorption charac
teristics.
W
e
optimize the ply orientation of a chin bar made of fibre
-
reinforced
composite layers
for
reduction of the neck force in a dummy model
using a computational approach
. We
use
the
fini
te element model of
a
human head/neck surrogate
and
measure
the
neck
axial force, which
has been shown to be
correlated
with
the risk of basilar skull fracture.
The results show t
hat by
varying
the orientation
of the chin bar
plies
,
thus
keeping the helmet
mass constant,
the
neck
axial force
can
be
reduced by
approximately
3
0
%
while
ensuring that
the helmet
complies with
the
impact attenuation
requirements
prescribed in helmet standards
.