奈米碳管複合材料斷裂疲勞與壓電複合材料壓電性質分析

Fracture and Fatigue of CNT Composites and Electromechanical Properties of Piezoelectric Composites

章正翰(Zheng-Han Zhang)

指導教授 ： 余念一

元智大學/工程學院/機械工程學系/博士(2013年)

https://doi.org/10.6838/YZU.2013.00010

摘要

以奈米碳管複合材料的破壞疲勞性質以及壓電材料的機電性質為此研究的主要目的。在複合材料的破壞疲勞實驗中，使用DER-331環氧樹脂為基材，D.E.H. 26為硬化劑，加強材為兩種不同尺寸的多壁奈米碳管，此兩種碳管的管徑分別為小於50奈米以及50 - 100奈米，而長度約為0.5 - 500微米。
在疲勞實驗中，首先建立穩定的奈米碳管複合材料製程，分別以平滑與有缺口的純環氧樹脂、0.5 wt%多壁奈米碳管複合材料試片來進行疲勞實驗，再將實驗結果繪製成應力振幅與生命週期曲線，並藉著曲線得到估計方程式，結果發現，在不同負載下，添加了奈米碳管的試片平均生命週期皆較純環氧樹脂試片的平均生命週期提升了1.26 - 3.56倍，而平滑試片的平均生命週期也較缺口試片的生命週期提升了5.94 - 20.31倍。
另外破壞實驗則是著重於奈米碳管重量百分比和碳管管徑對破壞韌度的定量影響關係。根據ASTM-D5045規範，以管徑小於50奈米的碳管製作1 wt%和3 wt%的破壞試片，並將實驗結果與以管徑為50 - 100奈米的奈米碳管進行的實驗結果進行比較，可以發現破壞韌度提升了46%。
由疲勞與破壞實驗的結果，可以明顯看出奈米碳管有提升複合材料機械性質的功用，而且隨著重量百分比的增加，提升效果更為顯著，而且小管徑的碳管比大管徑的碳管具有更高的機械性質，並且以雙重複合物模型為基礎建立一個數學模型用來估計奈米碳管管徑對整體複合材料彈性性質的影響。
而壓電材料的模型則是針對內含纖維及圓球狀異質物複合材料的彈性係數、壓電常數以及介電常數，進行估算，結果發現，整體複合材料的性質不但會隨著內含物的體積百分比增加而改變，並且會因內含物種類、形狀而有不同的變化量。模擬所得結果與文獻中的數據比較，也呈現相同的趨勢。

關鍵字

奈米碳管 ； 壓電材料 ； 破壞性質 ； 疲勞性質 ； 壓電性質 ； 複合材料

並列摘要

The present work experimentally characterizes the mode-I fracture toughness and stress life (S-N) curve of multi-walled carbon nanotube (MWCNT) reinforced epoxy matrix composites. The epoxy resin is DER-331 and the hardener is D.E.H. 26. The diameters of as-received MWCNT are (i) 50 - 100 nm and (ii) less than 50 nm; their lengths range 0.5 - 500 μm.
The effects of MWCNT weight fraction and notch on the fatigue behavior of MWCNT/epoxy composites are studied. Unnotched and notched neat epoxy and 0.5 wt% MWCNT composite specimens are manufactured and tested under various cyclic loadings, and consequently stress-life curves are constructed. The 0.5 wt% MWCNT/epoxy composites’ fatigue lives are 1.26 - 3.56 times of the average fatigue lives of neat epoxy, and the fatigue lives of unnotched specimens are 5.94 - 20.31 times of average lives of the notched specimens.
The effects of carbon nanotube weight fraction and diameter on the composite fracture toughness are studied. According to ASTM D5045, 1 wt% and 3 wt% MWCNT/epoxy composites are manufactured and MWCNT with diameters being less than 50 nm are used. One finds that the fracture toughness of the composites reinforced by small-diameter MWCNTs increase 46% in comparison with those reinforced by large MWCNTs.
A theoretical framework is developed to estimate the effective elastic modulus of CNT/epoxy composite.
The overall elastic modulus, piezoelectric modulus, dielectric modulus, and piezoelectric coefficient of piezoelectric composites containing piezoelectric fibers or particles are estimated by the present periodic microstructural model. The results show that the overall electromechanical properties are dependent on the volume fraction, material properties, and geometry of inhomogeneities. The results are benchmarked with existing models.

並列關鍵字

Carbon Nanotube ； Piezoelectric ； Fracture ； Fatigue ； Electromechanical ； Composite

參考文獻

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