多壁碳管補強高分子樹脂之複材樑與三明治結構動態特性研究

Dynamic Properties of Composite Beam and Sandwich Structure with MWNTs Reinforcement in Polymer Matrix

謝宗翰(Tsung-Han Hsieh)

指導教授 ： 葉孟考

國立清華大學/工學院/動力機械工程學系/碩士(2006年)

摘要

奈米碳管具有優良的機械與化學特性，因此科學家們紛紛以奈米碳管為補強材來製作高性能的奈米複合材料。本文將以多壁奈米碳管補強高分子樹脂材料，探討此高分子複合材料於動態特性上的表現，其動態特性包含自然頻率與耗損因子。受動態負載之結構中所選用的材料直接影響機具結構的動態特性，加有奈米碳管的高分子樹脂，可提升材料的剛性，提升結構的共振頻率，減少因共振現象對結構的影響；而奈米碳管與高分子基材間良好的界面特性，可提升材料的阻尼特性。
本研究將以有限元素分析模擬結構的振動模態與自然頻率，並與振動實驗量測結果比較。實驗結果所獲得的振動頻譜響應曲線可利用半能量頻寬法計算材料之耗損因子。最後將高分子複合材料運用於三明治結構中核心部份，表面材料則選用碳纖維疊層板，探討不同纖維疊層角對三明治結構態特性的影響。由於有限單元分析需材料常數，因而也將材料進行拉伸實驗，由實驗結果探討奈米複材機械特性，最後以SEM觀察材料破壞表面，了解材料受拉伸負載的破壞機制與碳管於樹脂中的分佈情形。

關鍵字

奈米複合材料 ； 多壁奈米碳管 ； 動態特性

並列摘要

The carbon nanotubes (CNTs) have better mechanical and chemical properties. Researchers used CNTs as reinforcement to fabricate nano- composites. In this study, multi-walled nanotubes (MWNTs) were used to reinforce the polymer resin, and the dynamic properties of the nanocomposites were investigated experimentally. Dynamic properties such as natural frequency and loss factor were measured. When the structure was subjected to dynamic loading, the material used would influence the dynamic characteristics of the structure directly. The addition of MWNTs in the polymer matrix increased the stiffness and natural frequency of the structure, and decreased the effect of resonance. There is good interfacial characteristic between the MWNTs and polymer resin which increased the damping characteristic.
In this study, finite element analysis was used to simulate the structural mode shape and natural frequency, and the results were compared to the results obtained from the vibration test. Moreover, Half-Power Bandwidth method was used to calculate the loss factor from the frequency spectrum response. At last, polymeric composites were applied to the core part of the sandwich structure, and graphite/epoxy laminates were applied to be surface material. The effects of different ply-angle on the dynamic characteristics of graphite/epoxy laminates were investigated. Material parameters should be defined in the analysis. The specimen was subjected to tension test. With the test, the mechanical properties of nanocomposites were discussed. Finally, SEM was used to observe the fractured surface of nanocomposites to understand the failure mechanism of the material subject to tension loading and the distribution of the MWNTs in the resin matrix.

並列關鍵字

nanocomposite ； MWNTs ； dynamic propertits

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