Title: Evaluating biofidelity of Anthropometric Test Devices under the use of Pre-Pretensioners - Evaluation of future Pre-Pretensioner system with respect to injury levels
Abstract: Pre-pretensioner (PPT) seatbelts are equipped with an electrical pretensioner that
tightens the belt in safety critical situations and liberates some webbing if the driver is
able to avoid the hazard. These PPT seatbelts introduce new loading scenarios, posing
a requirement to evaluate the biofidelity of present-day Anthropometric Test Devices
(ATDs). This study evaluates the biofidelity of ATDs of different sizes in four predefined
positions under PPT seatbelt loading also considering the habituation effect.
Data from 5th and 50th percentile females, and 95th percentile male volunteers and their
corresponding ATDs- Hybrid III 5th and 95th percentile dummies, and a prototype
BioRID 50 percentile female dummy were analyzed. Evaluation of the biofidelity was
done by comparing the responses of volunteers and ATDs. Basic kinematics parameters were tracked with TEMA3.5-012 software and the seatbelt force, current
and voltage signals were obtained from the transducer. Corridors were generated with
the volunteer subjects’ mean response ±1 standard deviation. Hybrid III family does
not reproduce human-like motion of the head-neck complex under PPT loading due to
the stiffness of the neck and torso. The 50th
percentile female BioRID dummy shows
a reversed trend compared to the flexion-extension motion of the volunteers. Changes
in stiffness and damping properties may lead to improvements in biofidelity of these
dummies under low load conditions (PPT loading). In general, the small female
volunteers are observed to have larger head-neck rotation amplitudes, which may
contribute to higher whiplash risk in females. Large male volunteers show lower
backset reduction and low T1 kinematics compared to other sizes of volunteers. Some
volunteers exhibit limited range of head-neck motion compared to others, which may
be a result of neck muscle tension.
Current studies about PPT seatbelts suggest that there is a scope to develop more
powerful systems that may use higher forces to reposition the occupant before an
impact. This study identifies injury assessment reference values for neck injuries and
optimal force values for PPT development. Dynamic and static tests were conducted
with H-III6C and the BioRID50F prototype. Two safe crash pulses, one with a
maximum deceleration of 4g at
56ms
and
a
delta
V
of
9km/h
and another with a
mean acceleration of 6g and a delta V of 28km/h were used in child and adult ATDs
respectively. Neck injury assessment reference values
(NICprotraction and NIJ)
were
obtained from the dynamic tests and literature review. In static tests, neck injury
criteria for higher seatbelt forces were obtained to compare them with the previous
thresholds.
Forces
close
to
600N
might
be critical in children when seated slightly
leaning forward. Some test results were discarded due to technical limitations, hence
for future testing it is recommended to use sensors and data acquisition systems
according
to
the
low
loading
scenario.
Publication Year: 2015
Publication Date: 2015-01-01
Language: en
Type: dissertation
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