臺灣博碩士論文加值系統

具有高強度、高勁度、重量輕的複合材料，已在工程上廣泛被應用。具脫層複合材料疊層板受到壓縮外力時，常因脫層的存在，對複合材料的挫屈能力有甚大的影響。
複合材料由於其層狀結構、特殊的製造程序、或使用過程中受到異物低速撞擊，很容易使層與層之間的結合喪失，即脫層現象。本文是針對俱有圓形脫層的複合材料平板，當其承受平行於脫層平面的壓縮負荷時，利用有限元素法求出其挫屈負荷及所對應的挫屈模式。
本研究將其模擬成三維問題，以圓形脫層之半徑、脫層位置、平板的寬度為參數，藉著改變參數大小，求得挫屈負荷及挫屈模態，並在脫層尖端使用較密的網格，以抓住裂縫尖端的奇異性，確保結果的準確性。
結果顯示，脫層挫屈應力會隨著圓形脫層半徑增加而降低，而相對應挫屈模式，由整體挫屈改變至混合挫屈，再改變至局部挫屈；脫層位置愈接近表面，愈容易發生挫屈，且挫屈模式愈容易發生混合型及局部性挫曲。至於平板的寬度對挫屈應力隨著寬度增加稍微增加。

Due to their high strength, high modulus, and lightweight, composite materials are widely used in the engineering field. When compressive force is applied to delaminated composite plates, buckling may occur.
Delamination of composite materials often occurs due to laminated structure, manufacturing defects, or low-speed external impact. The buckling behavior of laminated plates with circular delamination under uniaxial compressive loading is studied here. Finite element methods are used to evaluate the buckling load and to determine the corresponding buckling modes.
In this study, the delaminated plate is modeled as a three dimensional problem. Three parameters, including radius of the delaminated region, the cross-sectional depth of the delaminated region, and plate width, are varied to evaluate the buckling load and the corresponding buckling modes. Uniform mesh refinement around the edge of the delaminated region is enforced to ascertain the singularity.
The results indicate that buckling loads decrease as the radius of delamination increases, and buckling modes change from a global type to a mixed type, then to a local type. The closer the position of the delamination to the plate surface, the more easily the plates buckle, and similarly, mixed and local buckling modes are easier to occur. Further, buckling loads increase slightly as plate width increases.

目 錄

中文摘要 …………………………………………………………………. i
英文摘要 …………………………………………………………………. ii
誌謝 ………………………………………………………………….. iii
目錄 …………………………………………………………………. iv
表目錄 …………………………………………………………………. vi
圖目錄 …………………………………………………………………. vii
符號說明 …………………………………………………………………. ix
一、 緒論……………………………………………………………. 1
1.1 前言…………………………………………………………… 1
1.2 文獻回顧………………………………………………………. 3
1.3 本文目的………………………………………………………. 5
二、 有限元素法……………………………………………………. 7
2.1 概述…………………………………………………………… 7
2.2 挫屈負荷預測分析……………………………………………. 8
2.2.1 線性挫屈分析…………………………………………………. 9
2.2.1.1 前處理…………………………………………………………. 10
2.2.1.2 求解……………………………………………………………. 11
2.2.1.3 後處理…………………………………………………………. 11


三、 結果與討論……………………………………………………. 17
3.1 形狀幾何參數設………………………………………………. 17
3.1.1 矩形單一脫層…………………………………………………. 17
3.1.2 圓形單一脫層…………………………………………………. 19
3.2 二維和三維矩形脫層挫屈負荷結果比較………..………….. 20
3.3 圓形脫層挫屈行為探討………………………………………. 21
3.4 臨界脫層長度…………………………….…………………… 25
四、 結論……………………………………………………………. 50
參考文獻 …………………………………………………………………. 51
自傳 …………………………………………………………………. 53

參考文獻
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