Biomechanical Study Of Occupant’s Neck With Complex Posture In Automobile Crash Accident

The cervical spine is the primary area where motor vehicle accidents cause serious injuries.Whiplash injuries are mild soft tissue injuries from neck motion under low rear impact.Whiplash injuries are difficult to objectively diagnose with medical equipment and can develop into a chronic condition with long-term effects on the patient’s life.Many researchers have identified only rear impact as a source of whipping injuries,but frontal impact has been shown to cause a significant number of neck injuries.Most research on neck injuries in automobile crashes has focused on the situation where the driver’s head is in a normal neutral position.However,drivers change their neck posture when performing tasks such as changing lanes,stopping,and steering.With the popularity of smartphones,driving with "heads down" is becoming a norm,which poses a great risk to their own and others’ traffic safety.Head and neck posture may be the only factor that affects the persistence of symptoms in patients with whiplash injuries.In order to study the effect of neck posture on neck injury during the collision in traffic accidents,the existing finite element model was used to preprocess the model postures of head and neck extension 20°,flexion 20°,left axial rotation 20°and left lateral bending 200 for collision simulation.Based on the volunteer experiment and the C-NCAP whiplash test,the rear impact simulation with or without the restraint of the headrest and the frontal collision simulation with seat belt restraint were carried out to study the head and neck motion laws in different postures during the collision.It was found that the posture of head lateral bending and axial rotation did not affect the overall neck motion process on sagittal plane during the impact.The posture of head flexion increases the S-shaped alignment of the neck in the initial phase of the posterior collision process.In the frontal impact,the S-shaped motion of the neck in the rebound phase appeared opposite to that of the rear impact.The extension posture and lateral bending posture have great influence in front impact,while the flexion posture has great influence on rear impact.Studies have shown that C4-C5 cervical vertebra is prone to injury.The traditional injury criteria such asNij and Nkm are not fully applicable to the study of impact injury situations in complex postures,and injury criteria like IV-NIC in three-dimensional directions need to be proposed and improved.