Effects of Helmet on Biomechanical Responses of Pilot's Intervertebral Disc under Vibration Environment
Objective To evaluate the effect of helmet on biomechanical responses of pilot's intervertebral disc under vibration environment.Methods A porous media finite element model of C5-6 segment was established based on the computed tomography(CT)images of an adult.Four loading conditions(A,B,C helmets and No helmet)were applied to the validated model with a duration of 3 600 s for vibration analysis.Considering the effects of vibration frequency,the maximum porous pressure(MPP)and maximum principal stress(MPS)of nucleus pulposus(NP)and annulus substance(AS)were obtained.Results The MPP of NP and AS decreased and became stable under the same vibration frequency.The MPS of NP and AS for B helmet was the maximum,followed by C helmet,A helmet and No helmet.The curve of MPS for B helmet was higher than that of C helmet,A helmet and No helmet.At the vibration frequency of 5 Hz and 9 Hz,the MPS of AS under four helmet conditions increased with time,and reached a constant value after 1 200 s.Under the same helmet condition,after loading for 1 200-2 400 s,the MPS of NP at 9 Hz vibration frequency was higher than that at 5 Hz and 1 Hz.The MPS of AS at 9 Hz and 5 Hz was close to each other,and both were higher than that at 1 Hz.Conclusions The helmet has an important effect on the MPP of NP and AS,and the increase of vibration frequency will lead to the increase of the MPS of AS.
vibration loadpilotneck injuryintervertebral disc degenerationporous media modellingporous pressure
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