20141011

電腦輔助分析標準作業程序 (SOP of CAE simulation)

電腦輔助分析標準作業程序 (SOP of CAE simulation)

以下是做結構分析及金屬成形 CAE 分析,將持續更新。
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一、準備 CAD 模型


1. 確認幾何

從產品到分析用之CAD模型,如果外型簡單,能直接拿來做 CAE 建模最好,不然還是自己花點時間,把不必要的小特徵(feature)拿掉,再拿來做 CAE 模型。建議在CAD環境下進行修改,在CAD環境中編輯遠比在CAE環境中編輯來的方便,若是 CAD 與 CAE 軟體間具有關聯性,在CAD所做的模型設計變更,能立即地轉換至 CAE 中。

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二、準備材料模型

1. 材料實驗

依照材料實驗規範(ASTM、JIS)準備試片、設定參數進行材料實驗,
常見的材料實驗有:

(1)材料塑流應力模型:鈑料拉伸試驗、圓柱壓縮實驗。

(2)材料摩擦特性模型:圓環壓縮試驗。
(3)臨界破壞值(critical damage value, CDV)


2. 將材料實驗資料轉換成數據模型。


(1)位移-負荷曲線圖(stroke - load curve)

(2)真實應力-應變曲線圖(true stress - strain curve)
(3)機械性質

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三、前處理-建立 CAE 模型(Pre-processor)


1. 幾何(Geometry)

確認單位、檢查CAD轉換至 CAE中,是否發生破面、
是否需要修復及重建曲面。

2. 網格(Element / Mesh)

(1)依分析類型選擇元素類型(element type):
           實體、實體-殼、殼元素(solid、solid-shell、shell)。

(2)實體元素可分成四面體(tetra)及六面體(hexa),
          網格大變形的鍛造適用四面體元素、
          材料流動平緩的擠製類成形則用六面體網格。
(3)殼元素則以積分點(integration points)數目應用在不同分析中,
          如3積分點用在金屬鈑金成形、5-7點則應用在彈回分析。
(4)檢查網格品質。
(5)網格自動 / 手動細化 (remesh)

3. 材料特性(Material properties):

彈性模數(K)、加工硬化指數 (n)、降伏應力 (Sy, yield stress)、
破壞值 (CDV, critical damage value)。

4. 邊界條件(Boundary conditions):
對稱面 (symmetry plane)、固定端 (Fix)、負荷 (load)。

5. 分析控制(Simulation controls):

步進控制 (step control)、停止條件 (stop criteria)。
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四、求解(Solver)


1. 求解器(solver)

依照分析類型(sim type)及元素類型(element type)
選擇適用的求解器進行求解。

2. 收斂性(convergence)


一般以誤差判斷收斂與否,常見為速度誤差(velocity tolerance)及
力量誤差(force tolerance)。
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五、後處理(Post-processor)

1. 結構強度分析(structure strength analysis):
    Modal,deformation,strain、stress。

(1)模態分析結果:結構變形的趨勢,振幅看變形程度。

(2)應力分析結果:看結構脆弱處。

2. 金屬成形分析(metal forming analysis):
    Deformation、strain、stress、damage。

(1)變形:材料流動,是否發生流動缺陷,如疊料(folding)。
(2)應變:變形激烈程度。
(3)應力:材料受壓、受拉、彈性變形 or 塑性變形。
(4)破壞:材料過度變形,發生破裂 or 失效。
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Enson. 

20141011-露西(Lucy)觀後感

20141011-露西(Lucy)觀後感


這部片,女主角(Lucy),一個表情演完一部片、一包藥幹掉一群人、一個人成了一支隨身碟,沒了,卻又到處都在。

露西(Lucy)意外被迫幫韓國人運藥物,卻不小心讓身體吸收了藏在體內的藥物,腦部開發從 10%激增到了 100%,知識在一瞬間就進入腦中,學習的速度好比直接下載瞬間完成。當 Lucy 得到了異於常人的超能力,她開始報復,一步一步將藥物回收 ... 回收的方法,嗯,就交給警察去辦吧。而弄趴對手的招式,根本就是海賊王的霸氣外露,手掌一揚的一瞬間,對手全倒、戰力全失。




當時間的流逝不再不可控制,進而得以逆轉、回到歷史現場,可以控制時間倒轉,看盡萬物的流轉,從現在、過去、到宇宙洪荒混沌初開,一切,是的,一切,彷彿人生走馬燈,沒想到,昨日種種,僅靠一支 USB 隨身碟就裝滿了!隨身碟?是的,Lucy 最後演化成了一支隨身碟 ... ...

這部科幻片,看到Lucy 開始變成電腦的時候,我想到了另外一部講人工智慧的『全面進化』(Transcendence);全面進化的劇情是,主角快掛了,但他決定要將自己的腦袋內的東西上傳到伺服器上,跟 Lucy 的隨身碟倒是有異曲同工之妙,身體沒了,但精神卻又到處都在 (I AM EVERYWHERE)


(Lucy: I AM EVERYWHERE)


(武狀元蘇乞兒,趙無極爆體)

另一個有趣的地方是:摩根弗里曼(Morgan Freeman),Lucy 跟 Transcendence 兩部片都有他的戲,也都扮演科學家的角色。

(全面進化 Transcendence )

(露西 Lucy)

這部片,當作在看海賊王就好,真要看這一類的科幻片,看全面進化(Transcendence) 比較有看頭。
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Enson.

20141006

Cold Roll Forming Process and Die Design for Double-Gutter Frame of Drawer Slider

Jinn Jong Sheu, Chia Cheng Hsieh,Cheng Hsien Yu (2015) Cold Roll Forming Process and Die Design for Double-Gutter Frame of Drawer Slider, Key Engineering Materials, Vol.626,

Abstract

In this paper, the main focus is to demonstrate a systematic method of designing the roll flower and corresponding dies for a double-gutter frame applied to the drawer slider. The blank development method was proposed to calculate the width of blank for bending with small radii. The cold roll forming process design was based on the maximum longitudinal strain minimization and the interference of rolls with the double-gutter geometry of product profile. Extra pre-bending was designed to avoid the occurrence of blank collision during forming process. The FEM method was adopted to evaluate the process and die designs. Due to the geometry complexity of the product, strain distribution is uneven which results in more spring back and stress concentration. A geometry setting design was proposed to create local strain redistribution and smooth strain distribution of entire section profile after final forming step. Using geometry setting die design, the spring back at the end point and the gutter areas of final product section are 0.07 mm and 0.1 mm, respectively. Without the geometry setting die design, the spring back at the end point and the gutter areas of final product section are 0.11 mm and 0.15 mm, respectively. The simulation results demonstrate the proposed methods are able to improve the accuracy of cold roll forming products.

Keywords : Cold Roll Forming Die Design;Double-Gutter Frame of Slider;Roll Flower Design;Sprig Back Control

http://www.scientific.net/AMM.419.395

Cold Forging Die Design and Process Simulation of a Disk with Inner Ring Gear

Cheng Hsien Yu,Jinn Jong Sheu (2015) Cold Forging Die Design and Process Simulation of a Disk with Inner Ring Gear, Key Engineering Materials, Vol.626, pp.211-216.

Abstract

Cold forging die design and process simulation were studied in this paper for a disk with center boss and outer ring gear. The complexity of part geometry results in defects of under-filling and folding. The material flow interference in the radial and the axial directions at the corner areas is the main reason of the occurrence of defects. A multi-stage cold forging process was proposed to control the material flow and volume distribution simultaneously. FEM simulations were carried out to evaluate the designs of process and die. The proposed preform and web geometry designs were able to decrease the forging load and control the material flow. The simulation results showed the proposed methods were able to make this forged part without defects.

Keywords : CAE;Cold Forging;Multi-Stage Forging;Preforming Design;Ring Gear

http://www.scientific.net/AMM.419.395

Preform and Die Designs for Hot Forging Process of Linear Slide Block

Cheng Hsien Yu,Jinn Jong Sheu (2013) Preform and Die Designs for Hot Forging Process of Linear Slide Block, Applied Mechanics and Materials, Vol.419, pp.395-400.

Abstract

In this study, the preform and die designs of hot forging process were proposed for a long-flat slide block. This block is assembled to the linear slide for carrying the moving table. Three different billet geometry designs were proposed to obtain good die filling. The volume of the flash is limited to 30% with a flash thickness design in 3 mm. The forging die was designed with four ejectors to push up the forged part smoothly. The proposed billet geometries and die design were evaluated using CAE simulation. The simulation results indicated that the suitable perform design is able to achieve better material flow. The flash flow control is able to reduce the forming load and improve the die filling. The forging experiments were carried out to verify the proposed method, the experiment results showed good agreement with the CAE simulations.

Keywords: Forging Die Design;Hot Forging;Linear Slide Block;Preforming Design

http://www.scientific.net/AMM.419.395

20141001

20141001-線上取出PDF內嵌圖片工具 (ExtractPDF)

20141001-線上取出PDF內嵌圖片工具 (ExtractPDF)

取出 PDF 內圖片的線上工具:http://www.extractpdf.com/

操作方法:

(1)上傳PDF

(2)網站取出圖片

(3)點擊圖片下載
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Enson.