臺灣博碩士論文加值系統

本論文之目的在於解析不銹鋼雙極板微流道沖壓製程的成形性與微觀尺寸效應之影響。研究中提出以剛性沖頭對長、寬皆為50mm，厚度為50μm 的不銹鋼薄板(SUS 304)進行微沖壓製程，並在每一極板上製作出21條陣列式梯形流道，其流道寬度及深度分別為0.8與0.75mm。透過有限元素法與實驗比對，以尋求最佳製程參數。本文之有限元素法是運用Prandtl-Reuss之塑流法則，結合有限元素變形理論與updated Lagrangian formulation(ULF)觀念，建立一庫侖摩擦法則之增量型彈塑性大變形有限元素分析程式以模擬不銹鋼雙極板微流道之成形製程。本論文中亦運用選擇性減化積分法SRI (slective reduced integration)與四節點四邊形退化殼元素所推導之形狀函數至剛性矩陣中。在處理彈塑性狀態及模具與板料間的接觸問題，則採用廣義的 方式處理，此方式可有效處理彈塑性狀態的計算上的問題，並且延伸到處理模具與板料之間的接觸問題。而微觀材料參數則以傳統拉伸試驗求得知數據，針對不同厚度(0.05、0.1、0.2、0.3、0.4、0.5、1.0mm)變化進行比例式之修正，以得出具有微觀尺度效應之材料式，如此可使有限元數分析更加精確。
本論文之研究重點在於探討傳統巨觀材料參數與比例因子修正後的材料參數之差異，以觀察尺寸效應之影響。藉由模擬與分析微沖壓成形製程之全部變形履歷資料、衝頭負荷與衝程之關係、應力與應變分布、厚度分布、X-Z平面與Y-Z平面流道截面深度及截面厚度，並透過試驗結果驗證。另外，加入不同參數變化如:摩擦力、正交異向性值、模具倒角、板料厚度與流道形狀 (梯形、方形、三角形、半圓形)等進行微沖壓製程，由結果指出最容易出現破裂區域均在主流道與次流道之轉角處。而不同流道形狀的成形性，經分析後得到半圓型具有較佳的成形性，其次是梯形。由研究結果顯示利用微沖壓製作薄不銹鋼雙極板不僅可降低成本也可加速生產時程，而本文以ULF(Updated Lagrangian Formulation)的觀念建立一彈塑性大變形有限元素分析模式，並比較傳統巨觀應力-應變關係式與比例因子修正後的關係式，結果指出修正後的材料式較能符合實際成形情況，該比例法亦可運用於SUS304不銹鋼微觀任意厚度得修正，以省略繁複的拉伸試驗。除了應用所建立之分析程式之外，並選取SUS 304進行微沖壓成形之實驗，將可作為日後進行微衝壓測試之參考。
本論文所提出之方法能夠有效的模擬不銹鋼金屬雙極板之微流道沖壓製程。因此，可廣泛應用在各種流道形狀的沖壓製程上，建立完善分析數據及預估微沖壓過程中產生的各式問題，有利降低試誤損失及增進生產速率，進而使得燃料電池可朝向更精確微小化之發展。

The aim of this study is to resolve the stainless steel bipolar plates with micro channel forming form stamping process and micro-size effect of the impact. Regarding the use of rigid punch on 50μm-thick stainless steel sheet (SUS 304) for micro-channel stamping process in this study, the channel design is 0.8*0.75mm. Besides, the finite element method and the experimental results are used to analyze the micro-stamping process key parameters. The use of finite element method and experimental comparison, to find the best process parameters.
The methodology of elasto-plastic three-dimensional incremental finite element model is based on Updated Lagrangian Formulation (ULF). It associated Prandtl-Reuss flow rule and Hill's yield criterion respectively. The shape function derived from a four-node quadrilateral degenerated shell element associated and used selective reduced integration into the stiffness matrix to constitute the finite element model. An extended algorithm is proposed to formulate the altered elasto-plastic state of material, the increment of element and the nodal penetration or separation of mold and blank. The micro material parameters places that the traditional tensile test data requirements for different thickness (0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0 mm) of proportional changes in the amendment to come to a micro scale effects of the material type, so the number of finite element analysis can be more accurate. This study focused on exploring the traditional macro material parameters and scale factor corrected material parameters of the differences, in order to observe the effect of size effect.
The Simulation results include the whole deformation history, the relationship between punch load and punch stroke, stress and strain, the distribution of thickness XZ plane and YZ-plane cross-section depth and thickness, during the stamping process were obtained. Changes such as adding different parameters: friction, normal anisotropy value, die chamfer, sheet metal thickness and flow channel shape (trapezoidal, rectangular, triangular, hemispherical) and other micro-stamping process, the results indicate that the most prone to rupture region are in the main channel and sub-flow channel of the corner. Different flow channel shape formability, obtained by the analysis of semi-circular with better formability, followed by the ladder. The results shown by the use of micro-stamping sheet metal bipolar plate production not only reduces costs but also speed up the production process, In this paper, using ULF (Updated Lagrangian Formulation) concept to establish an elastic-plastic deformation finite element analysis model and using scale-factor to modify the calculation could effectively simulate the micro-stamping process for metal bipolar plates. The results indicate that the revised material style more in keeping with the actual shape of the scaling method can be applied to any thickness of SUS304 stainless steel micro was amended to omit the complex tensile test. In addition to applications outside of the establishment of the analysis program, and select the SUS 304 micro-stamping of the experiment, will serve as a micro-stamping test future reference.
Method proposed in this paper can effectively simulate stainless steel bipolar plate of the micro-stamping process flow. Therefore, can be widely used in various flow on the shape of the stamping process, establish and improve the analysis of data and forecasts generated in the process of micro-stamping all kinds of problems, loss of benefit to reduce trial and error and increase the production rate, thereby making the fuel cell can move towards more accurate miniaturization of the development.

致 謝 --------------------------------------------------------------------------- I

中 文 摘 要 --------------------------------------------------------------------------- II

英 文 摘 要 --------------------------------------------------------------------------- IV

目 錄 --------------------------------------------------------------------------- VII

表 目 錄 --------------------------------------------------------------------------- X

圖 目 錄 --------------------------------------------------------------------------- XI

符 號 說 明 --------------------------------------------------------------------------- XIV

第 一 章 緒論--------------------------------------------------------------------- 1
1.1 前言--------------------------------------------------------------------- 1
1.2 研究動機與目的------------------------------------------------------ 2
1.3 燃料電池簡介--------------------------------------------------------- 4
1.4 燃料電池之雙極板元件--------------------------------------------- 6
1.5 研究方法--------------------------------------------------------------- 10
1.6 文獻回顧--------------------------------------------------------------- 11
1.6.1 微成形------------------------------------------------------------------ 11
1.6.2 金屬成形分析--------------------------------------------------------- 16
1.6.3 雙極板流道設計------------------------------------------------------ 18
1.7 論文架構--------------------------------------------------------------- 21
第 二 章 基礎理論--------------------------------------------------------------- 23
2.1 基本假設--------------------------------------------------------------- 23
2.2 有限變形之應力與應力率------------------------------------------ 23
2.3 有限變形之應變與應變率------------------------------------------ 28
2.4 有限變形之update Lagrangian formulation---------------------- 29
2.5 材料之彈塑性構成關係式------------------------------------------ 32
第 三 章 有限元素分析理論--------------------------------------------------- 37
3.1 剛性統制方程式------------------------------------------------------ 37
3.2 虛功原理之離散化--------------------------------------------------- 39
3.3 摩擦處理--------------------------------------------------------------- 40
3.4 三維曲度修正方程式------------------------------------------------ 44
3.5 退化殼元素Degenerated Shell Element--------------------------- 46
3.6 不同積分法則推導退化殼元素之剛性矩陣--------------------- 48
3.7 除荷之設定------------------------------------------------------------ 50
3.8 靜態顯函Static Explicit--------------------------------------------- 50
3.9 廣義 法之增量步驟的計算-------------------------------------
51
第 四 章 不銹鋼雙極板流道微沖壓製程分析------------------------------ 55
4-1 不銹鋼雙極板流道微沖壓實驗與模擬之簡介------------------ 55
4.2 研究步驟--------------------------------------------------------------- 56
4.3 實驗設備與微沖壓模具建構--------------------------------------- 58
4.3.1 實驗設備--------------------------------------------------------------- 58
4.3.2 微沖壓模具建構------------------------------------------------------ 61
4.4 實驗流程--------------------------------------------------------------- 63
4.4.1 拉伸試驗--------------------------------------------------------------- 63
4.4.2 試驗結果--------------------------------------------------------------- 64
4.5 比例因子修正之微觀彈塑性材料模型--------------------------- 65
4.6 材料參數--------------------------------------------------------------- 68
4.7 不銹鋼雙極板流道微沖壓製程之數值分析--------------------- 69
4.7.1 有限元素網格化處理------------------------------------------------ 69
4.7.2 邊界條件--------------------------------------------------------------- 69
4.7.3 彈塑性與接觸問題之處理------------------------------------------ 70
4.7.4 除荷處理--------------------------------------------------------------- 70
4.8 不銹鋼雙極板流道微沖壓實驗與模擬之結果分析------------ 71
4.9 摩擦係數對製程之影響------------------------------ 81
4.9.1 變化摩擦係數與衝頭負荷與衝頭衝程之關係------------------ 81
4.9.2 變化摩擦係數與最薄厚度之關係--------------------------------- 81
4.9.3 變化摩擦係數與最大應力之關係--------------------------------- 82
4.9.4 變化摩擦係數與最大應變之關係--------------------------------- 82
4.9.5 變化摩擦係數與斷面平均深度之關係--------------------------- 82
4.10 正交異向性對製程之影響------------------------------------------ 87
4.10.1 變化正交異向性與衝頭負荷與衝頭衝程之關係--------------- 87
4.10.2 變化正交異向性與最薄厚度之關係------------------------------ 87
4.10.3 變化正交異向性與最大應力之關係------------------------------ 88
4.10.4 變化正交異向性與最大應變之關係------------------------------ 88
4.10.5 變化正交異向性與斷面平均深度之關係------------------------ 88
4.11 模具倒角半徑對製程之影響--------------------------------------- 92
4.11.1 變化模具倒角半徑與衝頭負荷與衝程之關係------------------ 92
4.11.2 變化模具倒角半徑與最薄厚度之關係--------------------------- 93
4.11.3 變化模具倒角半徑與最大應力之關係--------------------------- 93
4.11.4 變化模具倒角半徑與最大應變之關係--------------------------- 93
4.11.5 變化模具倒角半徑與斷面平均深度之關係--------------------- 94
4.12 板料厚度對製程之影響--------------------------------------------- 99
4.12.1 變化板料厚度與衝頭負荷與衝程之關係------------------------ 99
4.12.2 變化板料厚度與最薄厚度之關係--------------------------------- 99
4.12.3 變化板料厚度與最大應力之關係--------------------------------- 99
4.12.4 變化板料厚度與最大應變之關係--------------------------------- 100
4.12.5 變化板料厚度與斷面平均深度之關係--------------------------- 100
4.13 不同流道形狀之影響------------------------------------------------ 104
第 五 章 結果與討論------------------------------------------------------------ 108
5.1 結論--------------------------------------------------------------------- 108
5.2 未來展望--------------------------------------------------------------- 109
參 考 文 獻 --------------------------------------------------------------------------- 111
附 錄 --------------------------------------------------------------------------- 119

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