醫療用螺栓之有限元素法力學分析

The Finite Element Analysis of Bio-material Screw

方亮彬(Lian-Bin Fang) ； 毛祚飛(Tsuo-Fei Mau)

《建國科大學報》 27卷4期 (2008/07) Pp. 1-12

https://doi.org/10.6995/JCTU.200807.0001

摘要

由於螺栓或螺絲(bolt or screw)於組合結構件或機械元件時，具有使組合件容易組合、易於拆解與易於保養等優點，因而以螺栓為主的組合方式仍為常見的機件組合方法之一。隨著科技的進步與使用對象的不同，對於組合件的品質要求，或是其間所衍生的破壞或疲勞等問題持續仍為學者所關注，如以要求嚴格的醫療用骨釘和牙釘而言，由於仍須考慮骨骼再生的問題，所以除了要求能達到固定與組合的效果外，尚需考量植入後各螺紋的應力分佈的情形，以避免因為應力遮蔽效應(Stress shielding)影響骨骼再生。對於不論是考慮螺栓鬆脫、破壞或是醫療用骨釘和牙釘等的相關問題，計算螺栓各螺紋上力量或是應力分佈成了無法避免的問題，因此本文將考慮利用三維有限元素分析，來探討承受軸受負載螺栓與不同材質螺帽組合時，各螺紋上力量的分佈，以做為未來相關於螺栓強度、疲勞或是骨釘設計上之參考。
由分析結果顯示，改變螺帽的材質會影響作用在螺紋上的應力分佈形式，尤其是對高剛性的螺帽而言。另外於研究中也發現，改變螺栓的外徑，亦會對不同材質的螺帽上力量的分佈產生影響，尤其對螺栓外徑較小者影響較大；對於螺帽材質剛性較低者，其應力的分佈會趨於均勻。

關鍵字

螺栓 ； 螺帽 ； 力量分佈 ； 有限元素分析

並列摘要

The bolts and nuts are generally used in the assembling mechanical elements together to from structures, due to the merits that they can be easily assembled, disassembled, and maintained. With the progress of technology and different applied object, the demand of quality for the assemblies by bolts, or the related problems derived from assemblies by bolts are still concerned by researchers. In the case of bone screw and dental implant, with highly and strictly medical requirement, besides the consideration of fixation and assemblies of bone, the stress distribution between bone and screw still need to be taken into account to avoid the effect of stress shielding and adverse effect on bone remodeling. The problems related to loosening of threaded fasteners, fracture, bone screw and dental implant, determination of the stress and load distribution on the thread is inevasible. Accordingly, we utilize 3D finite element analysis to investigate the load distribution in thread for the bolt-nut connector with different material properties of nuts. The results can be used as the basis of further research for the behavior of strength and fatigue of bolt and bone screw.
The analyzed results show that the variation of the nut materials will affect the stress distribution on the thread, especially for the high stiffness. However, its effectiveness would not that prominent for low-stiffness nuts. Besides, the variation of the outer-diameter of bolts will also change the force distribution on the nuts with different materials. For the low stiffness nut materials, the stress distribution tends to be more uniform than those of high ones.

並列關鍵字

Bolt ； Nut ； Load distribution ； finite element analysis