Design And Simulation Analysis Of Active Head Restraint

About70percent of fatalities and injuries caused by rear-end collision arewhiplash injuries, which not only make patients suffer great pains, but cause hugesocial medical expenses. Most of the rear-end collision accidents occur at lowspeeds, usually less than25km/h. Therefore, how to prevent or reduce neckinjuries resulting from low-speed rear-end collisions is urgent to be solved.Currently, design of head restraints has comprehensively considered safety,comfort and side vision. However, as an anti-whiplash, it can only reduce13-18percent of neck injury. Therefore, it is urgent to design a head restraint which canenhance the protection of neck injuries in rear-end collision with consideration ofriding comfort.A finite element model of the driver seat was developed through the FE softwareHypermesh and validated by the pendulum impact test. The dynamic response of theoccupants in the rear-end collision was evaluated by the coupling model of the driverseat finite element model and the BioRIDII dummy model which was evaluated by theLS-DYNA/MADYMO coupling method. In this study, the effects of the parameters,including the height and backset, the seat-back stiffness and the head restraintstiffness, on occupant response were analyzed. The results suggested that height andbackset had the dominant influence on the neck injury risk. The reduction of thebackset and increase of the height lead to a decrease the neck injury risk.A new kind of active safety head restraint controlled by the crash accelerationsignal was presented in this thesis. Acceleration sensor is applied to real-time monitorthe signal of the vehicle acceleration. When the rear-end collision occurs and thestrength reaches the threshold set by the control system, the locking mechanisminstantly releases the head restraint to protect the occupant. The head restraint issimple in structure, reliable and reusable in working. The working principle,structural design and control system design were conducted in this thesis. A specimenof the head restraint was made and verified. The simulations between the active headrestraint and without the active head restraint were conducted.The results suggested that the new active head restraint can move32mmupward and38mm forward within60ms after the rear-end collisions happened.Compared to the original structure, the active safety head restraint could reduce the Neck Injury Criteria (NIC) value by33.8%and thus provide an effective protectionfor the neck in the rear-end collisions. The new active head restraint developed in thisstudy can not only improve neck injury prevention, but also have a reference value forfuture design of anti-whiplash device.