The Study Of Dynamic Response And Injuries Of Pilot's Neck Under High G Loading

With the development of technology and the need of war,the fighter has greater acceleration capability and maneuverability,resulting in the pilot bearing higher acceleration loading.The study show that the high G load has caused 70% of the pilot's neck discomfort,and more than 30% of the neck injury,which caused more serious loss of pilots and economic loss.Therefore,it is of positive significance to study the neck biomechanics and damage under high G load and to seek the cause of neck injury.The research results provide a theoretical basis for the design of the neck guard.We collected 3-dimensional information from MRI images by Mimics software and gained 3-dimensional point cloud data,process point cloud data in 3-matic to generate 3D geometric models,and divide mesh in ANSYS-ICEM-CFD and Hypermesh,we built a neck finite muscle element mode which concluded 24 pairs of muscles.The 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.Combined with the existing finite element model of the head and cervical vertebrae,the model was performed with cervical vertebra segmentation verification,Non-muscle finite element model verification and muscle whole model verification.Cervical segmental model validation is based on the in vitro study of cervical segmental segmentation of David J et al.and the cervical segmental segmentation simulation of Matthew B et al.;the Non-muscle model validation reference to Ningtingale et al.'s head-neck drop test and the simulation of Camacho et al.;muscle model validation refer to Ewing et al.'s frontal collision experiment and the simulation of Yang Jikuang et al.The results show that the model simulation data is basically consistent with the literature experiments and simulation data in the three verifications,which proves that the established finite element model can effectively reflect the head and neck kinematics and mechanical response of the human body.Can be used for neck injury studies under high G loads.The verified model was loaded with different acceleration,different acceleration directions,different acceleration growth rates,and arresting,launching condition,and the effects of various factors on neck injury were studied.The studies have shown that as the acceleration increases,the head and neck movements intensify,and the stress of each tissue(vertebra,disc,muscle)continues to rise,and the neck injury is more serious.When subjected to acceleration in the z direction,the stress on the vertebrae C4 and C5 is larger,and the force on the intervertebral disc C6-C7 is larger.When subjected to the acceleration in the x direction,the force on the vertebra C5 is the largest,and the intervertebral disc is the C6-T1 larger.When subjected to acceleration loads in different directions,the human body has the worse tolerance to acceleration in the x axis,and the z axis is better.Under the same acceleration,the NIC value in the x axis increases by 59.5% compared with the z axis.The rate of acceleration growth is proportional to the degree of neck damage.The 100G/s acceleration rate increases by 18.4% compared to 50G/s.In the arresting condition,the value of stress is the largest on C7 vertebrae,and the lower end disc was significantly higher than the upper end.Under the launching condition,the C5 vertebrae showed larger than others,and the disc also showed the same performance as the arresting condition.