| Lumbar disc herniation is a common disease in clinical medicine,which causes heavily burden in life and economic of patients.It is the foundation of the lumbar intervertebral disc that maintain the height of the spine and dispersing load,connecting the upper and lower vertebral bodies.Therefore,the intervertebral disc withstand complex and strong strength,so it is vulnerability.The etiology of lumbar intervertebral disc disease is complex,so far it hasn’t been accurately explained the reasons,but the clinical medicine shows that the key factors causing the disease is biomechanical factors.Therefore,in order to prevention of the occurrence of disc disease,it is necessary to further study the lumbar disc in a variety of load-bearing stressstrain state.In this paper,it is studied from two aspects that is the animal lumbar intervertebral disc experiment and the finite element simulation to discuss the mechanical properties and stressstrain regulation of different layers of lumbar intervertebral disc.In the experiment,it was carried out in situ with the lumbar intervertebral disc of the pig with the aids of the digital image-related technology,the stretching machine and other experimental equipment,which measured the displacement field and strain field of the strain.Integrated the analysis results of quantitative and qualitative,which can be obtained that the outer strain is smaller than the inner strain,and the upper layer strain is larger than the lower strain,and the strain on the ventral side is larger than the dorsal side.Through this experiment,it can also be found that the intervertebral disc under the action of the physiological load,which the fiber ring of stress-strain curve is nonlinear.In the finite element simulation,with the aid of reverse engineering technology software Geomagic studio,medical image processing software Mimics,and drawing software Solid Works,and through the finite element analysis software ANSYS to build a complete model of lumbar intervertebral disc,including fibers,the upper and lower end plates,nucleus pulposus,matrix,to give reasonable unit type and material properties.According to the results of clinical research,the changes of the different parts of the three kinds of lumbar vertebrae were simulated,which respectively is: first,to simulate the effect of 700 N in the lumbar spine when it is walking upright;second,to simulate the effect of 1000 N in the lumbar spine when it is siting still;Third,to simulate the effect of 5000 N in the lumbar spine when it is over loading.The load method is uniform distribution load,and select 458 nodes on the L1 vertebral body surface,loading the load evenly through the nodes.Simulation results show that: First,the strain on the ventral side of the fiber ring is larger than that of the dorsal side,which confirms the conclusion of the experiment;Second,the outer layer is greater than the inner strain when the load is evenly distributed and the fiber ring around the bulge;Third,the maximum stress appears in the articular process,and the stress changes from the outer layer to the inner layer.At last,the moment of the people in the movement is affected by the bending moment of 20 N.m and the effect of 50 N.m moment when is lifting the heavy weights are simulated.The changes of displacement field,stress field and strain field as well as the distribution law of the displacement field,the stress field and the strain field were discussed by using the nodal coupling loading method,and a brief analysis is carried out in this paper.The results of this study for the prevention and treatment of lumbar disc disease,repair of lumbar intervertebral disc defect and artificial lumbar disc material development etc.have important scientific significance. |
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