臺灣博碩士論文加值系統

近年來，越來越多的3D列印技術應用於生醫組織工程。尤其金屬積層製造方面被認為是最具應用潛力的一項技術，其中功能性孔洞梯度支架扮演著重要角色，因為該技術製作的材料使植入物在病患體內能夠有效的減少排斥現象，並避免應力屏蔽效應發生。
本研究透過選擇性雷射燒熔技術以鈦合金製造梯度多孔性結構，並進行結構設計及參數研究。內容主要分成兩部分，第一部分為了有效控制梯度多孔性結構材料之45°剪切斷裂現象，將參數分為: 1.保持相同的整體材料孔隙度，改變高孔隙度層數及排列方式，2.探討高孔隙度層數減少時，無法產生45°剪切斷裂的極限層數，第二部分探討應變率效應對高孔隙度層數的影響。研究結果顯示，當整體材料孔隙度相同，高孔隙度層數不同排列時，高孔隙區連續層數較低，高孔隙度每層承受偏移角度變大，材料強度降低更快。而當高孔隙度區層數達到一層時，多孔材料已無空間生成45°斷裂面之裂紋，因此小裂紋沿界面生成，顯示吾人可以選擇適當的多孔性設計，控制沿45°破壞的現象。第二，高孔隙度層數下降到一定比例時，應變速率會提高一個級別，變成衝擊測試，造成材料塑性變形量大幅下降。研究結果亦發現，當高孔隙度層數由8層減少到4層時，降伏應力大幅上升1.5倍，顯示在此過程出現穩態轉變至非穩態的轉折點。

In recent years, a growing number of 3D-printing technology has been applied to biomedical tissue engineering. In particular, additive Manufacturing is considered to be the most potential technology for it. Furthermore, functionally graded porous scaffold is used to avoid stress shielding effect and reduce the rejective reactions on implant of patients. In this study, we use Ti-alloy to manufacture functionally graded porous scaffolds by Selective Laser Melting, then design the structural of scaffolds and investigate the mechanical properties of each sample. The content is divided into two parts. First of all, in order to control the occurrence of shear fracture of functionally graded porous scaffolds under compression test, we use different number of high porosity layers and arrangement for parameters. Secondly, we investigate the effect of the strain rate effect on the number of high porosity layers. We have demonstrated that when the porosity of the whole material is the same and the arrangement of high porosity region is different, the sample with low continuous high porosity layer results in faster failure owing to the larger offset angle. Furthermore, the porous material has no space to develop 45° Shear fracture as the number of high porosity layer becomes one. Hence small cracks are formed along the interface. This indicates that we can control the occurrence of 45° Shear fracture by the design of high porosity layers. What’s more, as the strain rate increases a level and becomes an impact test high porosity layer drops to a certain percentage, resulting in a significant decrease in the amount of plastic deformation of the material. Finally, it is found that the yield stress increases by a factor of 1.5 when the number of high porosity layers are reduced from 8 layers to 4 layers. This shows a turning point of a process from a steady-state to an unsteady transition.

摘要 I
英文延伸摘要(Extended Abstract) II
誌謝 IX
目錄 X
表目錄 XII
圖目錄 XIII
符號表 XV
第1章 緒論 1
1.1 前言 1
1.2 文獻回顧 3
1.2.1 積層製造技術與應用之發展歷程 3
1.2.2 梯度結構組織工程 7
1.2.3 極小曲面（Minimal Surfaces） 8
1.2.4 多孔結構失效機制 11
1.2.5 應變率效應 15
1.3 研究動機與目的 18
第2章 實驗設備 19
2.1 選擇性雷射燒熔系統 19
2.2 萬能試驗機 20
2.3 相機 22
2.4 位移感測器LVDT 23
第3章 實驗步驟及方法 24
3.1 研究材料 24
3.2 樣品參數設計 25
3.3 計算參數 28
3.4 多孔結構製作 31
3.4.1 MATLAB 31
3.4.2 Materialise Magics 22.02 34
第4章 結果與討論 40
4.1 45°剪切斷裂之控制 40
4.1.1 均勻梯度結構壓縮結果 40
4.1.2 挫曲角度與高孔隙度層數之關係 41
4.1.3 高孔隙度層數與45°剪切斷裂之關係 43
4.2 應變率效應對高孔隙度層數的影響 43
4.3 穩態至非穩態區間 44
第5章 結論 47
參考文獻 48

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