Whiplash is a neck injury caused by the sudden differential movement between the
head and torso. Whiplash injuries are most commonly reported as a consequence of
rear impacts in car accidents. They are regarded as minor injuries, but can still lead to
long-term disablement and discomfort in the neck. Whiplash injuries can be
mitigated by better car seat designs. For this purpose, head restraint geometry must
be improved first, and then the dynamic performance of the whole seat must be
assessed at all crash seventies. A biofidelic human-body model is a key requirement
in designing whiplash mitigating car seats.
This thesis presents the development of a 50th percentile male multi-body human
model and several energy absorbing car seat designs. The human-body model is
specifically designed for rear impact and validated using the responses of seven
volunteers from Japanese Automobile Research Institute (JARI) sled tests, which
were performed at an impact speed of 8 kph with a rigid seat and without head
restraint and seat belt. A generic multi-body car seat model is also developed to
implement various seatback and recliner properties, anti-whiplash devices (A WDs)
and head restraints. Using the same driving posture and the rigid seat in the JARI
sled tests as the basic configuration, several anti-whiplash seats are designed to allow
different types of motion for the seatback and seat-pan.
The major findings of this research are:
-The human-body model simulates the effects of muscle contraction and its overall
response is superior in comparison to the currently used models and dummies.
-A criterion called the S-shape index (SSI) is developed based on the intervertebral
angles of the upper and lower cervical spine.
-The car seat design concepts are able to control and use crash energy effectively
with the aid of anti-whiplash devices for a wide range of crash seventies.
-In order to reduce whiplash injury risk, this study advocates energy absorbing car
seats which can also provide head restraint contact as early as possible.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.