本研究目的為建立積層製造(Additive Manufacturing)中的直接式能量沉積(Direct Energy Deposition，DED)模型。在模擬金屬受高斯雷射之加工過程中，假設基板需達到熔點形成融池，粉末才會開始沉積於基板上，並同時考慮表面張力(Surface tension)、馬倫格尼力(Marangoni force)、固化及液化模型，使金屬於相變化過程中更符合實際物理現象。於本文中，金屬粉末將假設為由經驗方程式而得之沉積率函數，以此建立三維模型。但由於三維模型計算量龐大，故將三維模型轉換為二維模型做計算，將空間軸(z)轉換為時間軸(t)，使雷射強度及粉末沉積速率呈現高斯分布於時間軸(t)與空間軸(x)上，朝等效二維模型發展。再以等效二維模型模擬三維熔覆層軌跡中穩定成長平台，此平台代表熔覆層高度及寬度幾乎不再隨進給方向而有所變化。
模型建立後，可透過大量模擬建立數值模擬融覆軌跡截面圖，得到加工參數，並預測加工結果，於實際加工前可避免選用易導致融覆層脫層之參數，減少原料成本浪費及尋找參數之時程。

The purpose of this study is to develop a numerical model presenting for a direct energy deposition process. In order to make the thermal and fluidic behaviors more accurate, the additional terms such as surface tension, Marangoni force, Gaussian laser, solidification and melting are considered. In this article, the assumption that the powder source term is a function derived from the empirical equation is applied to three-dimension model. However, due to the enormous computational time in three-dimension model, the equivalent two-dimension model, in which the space axis (z) is converted into time axis (t), is built. It means the laser intensity and powder deposition rate are distributed as Gaussian functions on x-t plane and therefore the three-dimension problem can be solved. The two-dimension model is used to simulate the deposition platform, of which the width and height are not changed with scanning direction in three-dimension model.
The laser tracks cross-section map established by numerous simulation results demonstrates clearly the process parameters, and is capable of predicting the results of actual processing. Furthermore, it is possible to avoid choosing the parameters leading to detached laser tracks and to lower the cost of raw material.

目錄
論文審定書 i
致謝 ii
中文摘要 iii
Abstract iv
目錄 v
圖目錄 vii
表目錄 ix
符號說明 x
第一章 緒論 1
1.1 積層製造背景 1
1.2 直接式能量沉積技術 3
1.3 文獻回顧 6
1.4 研究目的 11
第二章 研究方法 12
第三章 結果與討論 19
3.1 二維模型 19
3.1.1 等效二維模型 19
3.1.2 數值模型與流場設定 22
3.1.3 模擬結果 26
3.1.4 模擬分析 31
3.2 三維模型 36
3.2.1 數值模型與流場設定 36
3.2.2 模擬結果 38
3.2.3 以等效二維模型模擬三維模型 41
第四章 結論與未來展望 44
4.1 結論 44
4.2 未來展望 45
參考文獻 52

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