The Effect Of Muscle Activation On The Dynamic Response Of The Head And Neck In Lateral Impact

Unlike the frontal and rear part of a car,the energy absorption space of lateral side is small,which results in serious or even fatal injuries of occupants in lateral impact accidents.Head and neck injuries are found the most common and fatal injuries in vehicle accidents.Due to the complexity of the cervical anatomical structure and the physiological characteristics of the human body,volunteer tests,corpse and mechanical dummy tests can't help researchers to explore the effects of cervical muscle on head and neck injury.The aim of this paper is to develop a high biofidelity FE model of human head and neck with muscle activation in lateral impact condition,and to study the effects of neck muscle activate behavior on the dynamics and biomechanical responses of head and neck under different impact intensities.A solid element muscle model representing a 50th percentile male was developed based on the geometry reconstruction from MRI,and replaced the discrete element muscle model of HBM-Head-Neck FE Model II.The muscles were modeled coupling with solid elements and Hill elements representing passive and active behavior,in which the active elements were integrated in the solid mesh with shared nodes.The solid elements were defined as nonlinear-elastic and viscoelastic material.The validity of the finite element model of head and neck is verified under the condition of lateral impact.A full-scale occupant FE model was then developed merging the above model with dummy model ES II,and was validated in lateral impact condition with restraint system..The biomechanical responses of head-neck in different impact intensity were analyzed considering the real impact condition with a validated car model.The results show that the active behavior of neck muscle has a positive effect on the dynamic response of head and neck in low-intensity lateral impact,that the neck muscles can maintain the head posture and reduce the pressure on the disc during impact.However,within the middle and high intensity impact,the active behavior of neck muscle has no significant effect on the dynamic response of head and neck In middle and high intensity lateral impacts,the head bent to the shoulder and reach the limit position,which results in greater injury risk than that under low intensity impact and neck muscle activation has little effect on it.