The Experimental Study And Finite Element Analysis On The Mechanical Properties Of Dic Under Physiological Loads

Lumbar Intervertebral Disc Herniation is one of the common diseases of spine and the main reason for lumbocrural pain, which brings a serious threat to physical and mental health of patients, making heavy burden to modern society. Long-term mechanical load or overload is considered to be an important cause of disc degeneration. Disc Herniation has close relationship with its mechanics behaviors, so it is necessary to study the mechanical behaviors of interertebral disc under physiological loads, which will provide a theoretical basis for the prevention and clinical treatment of Disc Herniation, and be significant in evaluating mechanical properties of disc and constructing artificial disc.This topic studied the mechanical behaviors of animal lumbar disc under physiological loads by experiment and simulation. Compression experiment of animal lumbar segment and measurement of strain field on the surface of disc under physiological load were completed.The first experiment got the load-displacement curves of lumbar segment under compression,which is nonlinear. The second experiment studied the mechanical state on the surface of disc under compressive and bending loads using the digital image correlation techniques and the results show that the distribution regularity of strain field under bending load is obvious.At the part of simulation, this study used the technology of reverse engineering and established a complete model of animal lumbar segment including intervertebral disc which contained annulus matrix, annulus fiber, nucleus pulposus and endplates, using 3D image creating and editing software Mimics, reverse engineering software Geomagic Studio,three-dimensional graphics software Solid Works and finite element analysis software ANSYS,based on CT scanning technology. Then we analysed the model under compressive, bending and torsional loads and compared the results of simulations and experiments. The results are basically consistent, which confirms that the established model has higher feasibility and the simulation results has reference value. The results of finite element analysis conclude that the maximum stress appeared under torsional load, which shows torsional load is most likely to make the annulus fail, causing Disc Herniation. The stress state of annulus fibers indicates that the oblique and crossed growth pattern of annulus fibers protects the disc well. Then we studied the effects on the mechanical properties of the disc by simulation. The results show:(1) fiber and nucleus pulposus both affect the mechanical properties of the disc and the influence of fiber is more obvious than nucleus pulposus;(2)the strain on the complete disc model under different loads is smaller than other incomplete models;(3)compared to other loads, torsional load always have the greatest effect on all disc models.