發(fā)布時(shí)間：2018-09-07 19:19

【摘要】：腰椎間盤具有多孔粘彈性質(zhì),髓核中的液體在應(yīng)力作用下,可以在組織中流進(jìn)或流出,因此具有吸收能量和緩沖的功能,對(duì)維持脊柱的靈活運(yùn)動(dòng)及穩(wěn)定性、分散和緩沖載荷起到重要作用。在外力作用下,椎間盤的纖維環(huán)如果破裂,髓核組織從破裂之處脫出,將導(dǎo)致相鄰脊神經(jīng)根遭受壓迫或刺激,引起下腰痛病癥,因此腰椎間盤突出癥是臨床上的常見疾病。由于椎間盤的力學(xué)行為對(duì)其產(chǎn)生退變有很大的影響,故研究各種載荷作用下椎間盤的生物力學(xué)特性,為臨床上治療腰椎間盤疾病提供了理論依據(jù)。本文主要采用有限元方法對(duì)腰椎間盤的力學(xué)行為進(jìn)行仿真研究,對(duì)蠕變性能進(jìn)行實(shí)驗(yàn)并建立蠕變本構(gòu)方程。利用ANSYS軟件建立正常人體腰椎間盤L3~L4節(jié)段的有限元模型,基于Biot理論考慮了流固耦合關(guān)系,分析了椎間盤在不同軸向壓縮載荷及復(fù)合載荷作用下的力學(xué)響應(yīng),得到了椎間盤各個(gè)部分的壓力、應(yīng)力分布規(guī)律和比較曲線。結(jié)果表明:軸向正壓時(shí),外層纖維環(huán)壓力約為內(nèi)層的15%,外層最大應(yīng)力約為髓核的4.3倍;椎間盤各部分所受壓力隨載荷增大呈近似線性增加,且增加的速率基本相同;應(yīng)力隨載荷增加而增大的速率不同,最外層纖維環(huán)應(yīng)力增加最大。軸向壓縮與扭轉(zhuǎn)載荷組合作用時(shí),纖維環(huán)整體應(yīng)力水平最大,最容易被破壞。利用ABAQUS軟件的多孔彈性有限元模型,對(duì)椎間盤在壓縮應(yīng)力下的蠕變特性進(jìn)行了研究,得到的位移-時(shí)間曲線呈指數(shù)規(guī)律變化,應(yīng)力增大時(shí),應(yīng)變隨之增大。以新鮮豬腰椎間盤為研究對(duì)象,采用非接觸式數(shù)字圖像相關(guān)技術(shù),對(duì)不同壓縮應(yīng)力及加載速率下的椎間盤進(jìn)行蠕變實(shí)驗(yàn)。結(jié)果表明:壓縮應(yīng)力作用下,椎間盤蠕變曲線呈指數(shù)規(guī)律變化;相同加載速率下,蠕變的應(yīng)變隨著應(yīng)力的增大而增大;相同應(yīng)力下,加載速率越大,蠕變應(yīng)變?cè)叫�。利用三參�?shù)粘彈模型建立椎間盤蠕變本構(gòu)方程,并與實(shí)驗(yàn)結(jié)果進(jìn)行比較,二者具有較好的相關(guān)性,本構(gòu)方程能夠預(yù)測(cè)椎間盤的蠕變性能。研究結(jié)果為臨床上進(jìn)一步研究人體椎間盤粘彈特性提供了理論基礎(chǔ)。
[Abstract]:The lumbar intervertebral disc has porous viscoelasticity, and the fluid in the nucleus pulposus can flow in or out of the tissue under stress, so it has the function of absorbing energy and buffering, which can maintain the flexible movement and stability of the spine. Dispersion and buffer load play an important role. Under the action of external force, if the fibrous ring of intervertebral disc ruptures, the tissue of nucleus pulposus will come out from the ruptured place, which will result in the compression or stimulation of adjacent spinal nerve root, and cause the disease of lower back pain, so protrusion of lumbar intervertebral disc is a common disease in clinic. Because the mechanical behavior of intervertebral disc has great influence on its degeneration, studying the biomechanical characteristics of intervertebral disc under various loads provides a theoretical basis for clinical treatment of lumbar intervertebral disc disease. In this paper, the mechanical behavior of lumbar intervertebral disc is simulated by finite element method, the creep behavior is tested and the creep constitutive equation is established. The finite element model of L3~L4 segment of normal human lumbar intervertebral disc was established by using ANSYS software. Based on the Biot theory, the fluid-solid coupling relationship was considered, and the mechanical response of the disc under different axial compression loads and composite loads was analyzed. The pressure and stress distribution and comparison curves of each part of intervertebral disc were obtained. The results show that the pressure of the outer fiber ring is about 15 times of that of the inner layer and the maximum stress of the outer layer is about 4.3 times of that of the nucleus pulposus under positive axial pressure, and the pressure on each part of the intervertebral disc increases approximately linearly with the increase of the load, and the increasing rate is basically the same. The stress increases at different rates with the increase of load, and the stress of the outermost fiber ring increases the most. When combined with axial compression and torsional load, the overall stress level of the fiber ring is the largest and the most easily destroyed. The creep behavior of intervertebral disc under compression stress is studied by using the porous elastic finite element model of ABAQUS software. The displacement-time curve changes exponentially and the strain increases when the stress increases. The creep experiments of fresh porcine lumbar intervertebral discs under different compression stress and loading rate were carried out by using non-contact digital image correlation technique. The results show that the creep curve of intervertebral disc changes exponentially under compressive stress; at the same loading rate, the creep strain increases with the increase of stress; under the same stress, the higher the loading rate, the smaller the creep strain. A three-parameter viscoelastic model was used to establish the creep constitutive equation of intervertebral disc. Compared with the experimental results, the constitutive equation can predict the creep behavior of intervertebral disc. The results provide a theoretical basis for the further study of viscoelastic properties of human intervertebral disc.
【學(xué)位授予單位】：天津理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：R681.53

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