| Discomfort,fatigue and low back pain caused by driving activities have become the urgent problems to be solved in the area of car seat comfort research.Reasonable car seat design can effectively improve the car ride comfort.This paper aims to establish a unified multi-source information model of human biomechanics that can reflect the human body pressure distribution and biomechanical characteristics of human lumbar spine,and use the model to explore the internal influence mechanism of automobile seat design parameters on seat comfort.Based on the geometric model of human lumbar spine in Poser software database,a finite element model of lumbar spine containing detailed ligaments,intervertebral discs and collagen fibers was established by Hypermesh software.The physiological characteristics of the finite element model of lumbar spine were verified under various load conditions with range of motion,intervertebral disc compression and intradiscal pressure as the evaluation indexes.The results showed that the range of motion,intervertebral disc compression and intradiscal pressure of the finite element model of the lumbar spine were highly consistent with the previous experimental data and the finite element simulation results.Therefore,the model can accurately reflect the biomechanical characteristics of the human lumbar spine,and has a good biomimetic degree.On the basis of Hybrid Ⅲ dummy model,the verified lumbar finite element model was added,and the important parts of Hybrid III dummy model were adjusted and modified to establish a complete human finite element model.Through the body pressure distribution experiment and referring to the previous experimental research literature,the body pressure distribution characteristics,the body segment mass distribution and the biomechanical characteristics of the lumbar spine in the human finite element model were verified.The results showed that the body pressure simulation results were in good agreement with the experimental results,the body segment mass distribution of the human finite element model was reasonable,and the biomechanical characteristics of the lumbar spine were in good agreement with those of the predecessors.Therefore,the finite element model of human body has a good biomimetic degree.The finite element model of human body was used to explore the influence mechanism of car seat back angle on seat comfort,and the finite element model of human-seat system with seat back Angle of 5~°,7~°,10~°,13~°,15~°,17~°,20~°,23~°,25~°,27~°and 30~°was established for simulation analysis.The results demonstrated that when the seat back angle was in the range of 23~°to 30~°,the intradiscal pressure and the average annulus fibrosus stress of L1-S1 segments were significantly lower than that of the seat back angle in the range of 5~°to 20~°,and the change was not significant in the range of 23~°to 30~°.Meanwhile,the average pressure representing the static comfort of the seat was the smallest in the seat back angle range of 23~°to 30~°,the body pressure distribution between the human body and the cushion was the most uniform,and the pressure of the thigh full of nervous system and blood vessels was the lowest.Combined with the results of clinical medicine,the layout and design theory of automobile seats and the relevant enterprise standards of the automobile industry,23~°to 30~°is the comfortable range of automobile seat back angle,which indicates that the intradiscal pressure and annulus fibrosus stress can be used as the evaluation index of the seat comfort,and within the reasonable pressure or stress threshold,the lower the value is,the better the comfort of the car seat is. |
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