臺灣博碩士論文加值系統

本研究利用點應力準則與有限元素軟體ANSYS，探討含傾斜45o橢圓孔編織複合材料平板之破壞強度。首先將碳纖維編織布含浸環氧樹脂後，利用熱壓法將預浸材製成編織複合材料平板。然後利用金相顯微鏡觀察沿纖維紗束方向的斷面，求得紗束纖維的高長比，並計算纖維體積含有率。接著利用勁度平均法計算編織複合材料平板的等效工程模數，然後以實驗值驗證試片之軸向楊氏模數。其次，將編織複合材料平板加工成含傾斜45°之橢圓孔洞試片（短軸長度固定，長軸尺寸改變），並進行拉伸試驗，得到其破壞強度。接著，將試片之等效工程模數與拉伸實驗測得破壞強度輸入ANSYS中分析，得到含傾斜橢圓孔編織複合材料平板之孔邊的應力分布，且由點應力準則求出其特徵長度，並以最小平方法建立特徵長度與橢圓孔長軸半徑之函數關係。
最後為了驗證此研究之準確性，另行製作驗證試片，利用上述函數關係計算驗證試片之特徵長度並預測其開孔強度。結果顯示，預估值與驗證值之誤差僅在2.23%內，故本研究分法可準確的預測含傾斜橢圓孔編織複合材料平板之破壞強度。

In the work, the Finite Element software —ANSYS— and Point Stress Criterion are used for studying the fracture strength of braided composite plates each with an elliptical hole of inclined angle 45o. First, carbon fiber braid was impregnated with epoxy resin to make braided composite plates by hot-press method. Then, by means of metallographic microscope, we observed the cross-section of a specimen along the direction of fiber yarn weaving, and got the high length ratio and the fiber volume fraction. Furthermore, the Stiffness Averaging Method was adopted to calculate the equivalent engineering moduli of the braided composite plates, and the calculated axial Young’s modulus was then verified by experimental data. Carrying out the tension experiment with the specimens with various major axes (miner radius is fixed) which incline an angle of 45° to the horizontal is to get fracture strength of specimens. Next, the engineering moduli and the resulting fracture strengths of the experimental group are input into ANSYS for analysis to obtain the stress distribution beside the hole in this plate. Meanwhile, the characteristic length from the Point Stress Criterion is derived. Furthermore, the Least-squares method is adopted to set up a functional relationship between characteristic length and major radius.
Finally, in order to verify the accuracy of this study, specimens with different radius were made, and the functional relationship mentioned above was used to calculate the characteristic length and the predicted fracture strength. By comparison to experimental data, it is shown that our method can accurately predicted the notched strength of braided composite plates each containing an inclined elliptical hole with a maximum error of only 2.23%.

誌謝 I
摘要 II
Abstract III
目 錄 V
圖目錄 VIII
表目錄 XI
第一章 前言 1
1.1 引言 1
1.2 文獻回顧 3
1.3 研究動機 6
第二章 相關理論 8
2.1 編織物複合材料之工程模數計算 8
2.1.1 單位格子 9
2.1.2 單方向紗束工程模數計算 11
2.1.3 三維座標轉換 13
2.1.4勁度矩陣平均法 17
2.1.5 纖維體積含有率量測 19
2.2　點應力準則 20
2.3　基於有限元素點應力準則預測其開孔強度 22
第三章 實驗 24
3.1實驗材料 24
3.2實驗儀器 26
3.3試片製作流程 27
3.4研究流程 35
3.5金相實驗 37
3.6 編織複合材料平板之材料性質測試 40
3.7 拉伸實驗 41
3.8　CNC鑽孔加工 43
第四章 有限元素軟體分析 44
4.1 有限元素法ANSYS介紹 44
4.2　ANSYS軟體分析架構 46
4.2.1 前處理 47
4.2.2　求解器 50
4.2.3　後處理 51
第五章 結果與討論 54
5.1 編織複合材料之材料性質驗證 54
5.2 破壞模式 55
5.2.1 巨觀破壞模式 55
5.2.2 微觀破壞模式 57
5.3 孔洞半徑與特徵長度之關係 60
5.4 實驗組之強度預估 62
5.5 驗證組之強度預測 63
第六章 結論 64
參考文獻 65
附錄一 68

1.Photo by Kestrel Bicycles(SantaCruz, America)
2.Photo by 伸欣精密有限公司(Taichung, Taiwan)
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