【摘要】：生物鎂合金具有可降解性、優(yōu)異的生物相容性和生物安全性,是較有發(fā)展?jié)摿Φ墓锹葆斨苽洳牧�。與傳統(tǒng)的不可降解金屬骨螺釘相比,生物鎂合金骨螺釘強度較低,且應(yīng)力集中會影響其降解速度,因此原來不可降解螺釘?shù)慕Y(jié)構(gòu)不適用于生物鎂合金,需要對生物鎂合金骨螺釘進行結(jié)構(gòu)優(yōu)化,以更好地滿足臨床使用性能要求。目前,國內(nèi)外該方面的研究尚鮮見于報道。本文針對可降解生物鎂合金骨螺釘?shù)牧W強度不足,局部應(yīng)力集中加速腐蝕速度等問題,參考鈦合金、不銹鋼材料醫(yī)藥行業(yè)標準,建立股骨骨螺釘三維結(jié)構(gòu)模型,采用仿真分析軟件ANSYS對其進行力學性能的有限元分析,包括螺釘三點彎曲實驗、扭轉(zhuǎn)實驗和軸向拔出實驗的模擬,得到應(yīng)力應(yīng)變、總變形分布及結(jié)果。首先改變骨螺釘結(jié)構(gòu)特征,包括螺紋形狀和是否空心結(jié)構(gòu),并對改變前后的結(jié)構(gòu)進行力學性能的對比;其次分別改變螺距、內(nèi)徑和牙型角等骨螺釘結(jié)構(gòu)尺寸參數(shù),建立不同參數(shù)的模型,以力學性能模擬結(jié)果為目標函數(shù),探究各個尺寸參數(shù)對三點彎曲、扭轉(zhuǎn)和軸向拔出性能的影響規(guī)律及結(jié)果;最后在模擬計算結(jié)果的基礎(chǔ)上,通過正交試驗對多方面因素耦合作用進行分析,確定最優(yōu)螺釘尺寸參數(shù)并進行加工,進而對真實螺釘?shù)膶嶋H力學性能進行表征,校核模擬結(jié)果。研究結(jié)果表明:不對稱螺紋骨螺釘防脫出,且應(yīng)力集中程度降低;彎曲、扭轉(zhuǎn)性能模擬結(jié)果表明骨螺釘中心部分應(yīng)力較小,因此實心與空心直徑1mm的骨螺釘力學性能對比無明顯差別。內(nèi)徑的增加對彎曲、扭轉(zhuǎn)承載能力有一定程度的提升,但會降低骨質(zhì)與螺紋的咬合力;螺距對骨螺釘力學性能的影響沒有明顯規(guī)律;牙型角的增加對螺釘承載能力呈現(xiàn)先增加后減小的趨勢。通過正交試驗極差分析得到各參數(shù)對彎曲載荷的影響排序從大到小是內(nèi)徑、螺距、牙型角β和牙型角α;對扭矩影響排序是內(nèi)徑、螺距、牙型角α和牙型角β;對軸向拔出力影響排序是螺距、內(nèi)徑、牙型角β和牙型角α。綜合單因素變量分析結(jié)果和極差分析,選擇骨螺釘螺距1.45mm、內(nèi)徑3.2mm、牙型角α為2°、牙型角β為35°為最優(yōu)組參數(shù)。骨螺釘力學實驗和模擬結(jié)果基本吻合,驗證了有限元分析的正確性,優(yōu)化后比優(yōu)化前骨螺釘彎曲載荷提高83.5%;扭矩提高24.2%;但是對軸向拔出力并無明顯改善。本文通過對Mg-Zn-Y-Nd合金骨螺釘整體的結(jié)構(gòu)優(yōu)化,提升其力學承載能力,減小了應(yīng)力集中程度,建立起鎂合金骨螺釘尺寸的基本參數(shù)體系,為鎂合金骨螺釘最終用于臨床骨外科的植入提供數(shù)據(jù)參考。
[Abstract]:As biodegradable, biocompatibility and safety, magnesium alloy is a promising material for the preparation of bone screws. Compared with the traditional non-degradable metal bone screw, the strength of the biodegradable magnesium alloy bone screw is lower, and the stress concentration will affect the degradation rate, so the structure of the non-degradable screw is not suitable for the biological magnesium alloy. It is necessary to optimize the structure of biological magnesium alloy bone screw in order to better meet the requirements of clinical performance. At present, the domestic and foreign research on this aspect is rarely reported. Aiming at the problems of insufficient mechanical strength of biodegradable magnesium alloy bone screw and accelerated corrosion rate of local stress concentration, a three-dimensional structure model of femur bone screw was established by referring to the medical standard of titanium alloy and stainless steel material. The finite element analysis of mechanical properties was carried out by using the simulation software ANSYS, including three point bending test of screw, torsion experiment and axial pull-out experiment. The stress strain, total deformation distribution and results were obtained. Firstly, the structural characteristics of bone screw were changed, including the shape of screw thread and the hollow structure, and the mechanical properties of the structure before and after the change were compared, and the structural dimension parameters of bone screw such as pitch, inner diameter and tooth angle were changed respectively. The model of different parameters is established, and the simulation results of mechanical properties are taken as the objective function to explore the influence of various dimension parameters on the three-point bending, torsion and axial pull-out properties. Finally, on the basis of the simulation results, The coupling effect of various factors was analyzed by orthogonal test, the optimum screw size parameters were determined and processed, and the actual mechanical properties of the real screws were characterized and the simulation results were checked. The results show that the asymmetrical screw is anti-detachable and the stress concentration is decreased, and the simulation results of bending and torsion show that the stress in the center of the screw is small. Therefore, there is no significant difference in mechanical properties between solid and hollow diameter 1mm bone screws. The increase of inner diameter increases the bearing capacity of bending and torsion to a certain extent, but decreases the bite force of bone and thread, and the influence of pitch on the mechanical properties of bone screw is not obvious. The tooth angle increased first and then decreased. By means of orthogonal test range analysis, the order of influence of parameters on bending load is obtained, from big to small is inner diameter, pitch, tooth shape angle 尾 and tooth shape angle 偽, and the order of influence to torque is inner diameter, pitch, pitch, The order of influence on axial pull-out force is pitch, inner diameter, tooth angle 尾 and tooth angle 偽. According to the results of univariate analysis and range analysis, the optimal parameters were as follows: screw pitch 1.45 mm, inner diameter 3.2 mm, tooth angle 偽 2 擄, tooth angle 尾 35 擄. The experimental results of bone screw mechanics are in good agreement with the simulation results, which verify the correctness of finite element analysis. After optimization, the bending load of bone screw is increased by 83.5%, the torque is increased by 24.2%, but the axial pull-out force is not obviously improved. In this paper, by optimizing the structure of Mg-Zn-Y-Nd alloy bone screw, improving its mechanical bearing capacity, reducing the degree of stress concentration, the basic parameter system of the size of magnesium alloy bone screw is established. It provides data reference for the application of magnesium alloy bone screw in clinical bone surgery.
【學位授予單位】：鄭州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG146.22;R318.08

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本文編號：2184747