The Study Of Drives' Neck Injuries Analysis And Implication In The Rear Impact

The rear impact will cause about 90% drivers' neck injuries,which leads to a large number of casualties and heavy economic loss.So it's necessary to study neck biomechanical responses and injuries in the car rear impact and offer a automotive headrest position which directly relate to neck injuries scheme.We collected 3-dimensional information from CT images by Mimics software and gained high precision 3-dimensional geometric model,then combined with neck anatomical structure,we built a neck finite element mode which concluded C1-C7 cervical vertebra,T1 thoracic vertebra,7 intervertebral discs,10 groups of ligamenta,24 pairs of muscle and parts of cartilage tissues.The ligament model included anterior longitudinal ligament,posterior longitudinal ligament,ligamenta flava,alar ligament,supraspinal ligament,interspinal ligament,intertransverse ligament,Atlas occipital transverse ligament,posterior atlantooccipital membrane and capsular ligament.The muscle model contained scalenus anterior,scalenus posterior,scalenus medius,semispinalis,musculi multifidi,longissimus capitis,longissimus cervicis,splenius capitis,splenius cervicis,musculi patientiae,musculi obliquus capitis inferior,musculi obliquus capitis superior,musculi rectus capitis anterior,musculi rectus capitis posterior,musculus rectus capitis lateralis,omohyoid,serratus posterior saperior,sternocleidomastoid,trapezius,longus capitis,longus colli,sternohyoideus,sternothyreoideus.We used the model to verify necks without muscle and with muscle's dynamic responses.The Non-muscle neck and head model was verified by Nightingale et al.'s corpse head-neck axaial impact experiment,the head and neck with muscle model was verified by Davidson et al.'s rear impact experiment.The validation results showed two groups' simulation data and experiment data were similar,which proved the model can effectively reflect human head-neck kinematical responses and biomechanics responses that will be suited to study the neck injuries in the car rear impact.The verified head-neck model and the human biomechanics model,seats model and belt model of Chai Zhihua were engaged in rear impact simulation system.We simulated C-NCAP 2015 rear impact working condition and changed headrest and drives' head horizontal distance and vertical distance and the influence of headrest's position to neck injuries.The results demonstrated the headrest and drives' horizontal distance will cause the worst injuries and the longer the distance was,the injury worse.But if the distance was too short,the driver's head will repeatedly collide the headrest because of the belt strain.When headrest keep the suitable horizontal distance with head and no repeatedly collision,the NIC will relativelylower 11%~26%.While the headrest and drivers' vertical distance paralleled with headrest and head's top side,the NIC will relatively lower 13%.The dip angle of headrest influenced the head counter-acting force direction and then the neck curvature movement.If headrest anticlockwise inclined with small angle,the NIC will relatively lower 6%~11%.