發展微觀黏著-滑動模型以探討奈米碳管複合材料之阻尼性質

Abstract

本研究主要目的為發展微觀黏著-滑動模型以探討奈米碳管複合材料(Carbon nanotube composite)之振動阻尼性質。在解析模型中，藉由考慮奈米碳管與周圍基材產生滑動摩擦之現象來描述複合材料能量消散機制。此外，在本研究中亦探討奈米碳管長徑比、界面間之鏈結強度以及摩擦力對複合材料阻尼行為的影響。根據過去的研究指出，複合材料會因施加之循環負載量改變使阻尼行為也隨之改變，故探討施加之循環負載量對複合材料阻尼性質之影響亦為本研究之重點。 除了發展微觀力學模型之外，本研究也利用有限元素分析來驗證解析模型預測之正確性。為了模擬奈米碳管複合材料接觸摩擦行為，建立有限元素模型並在碳管與周圍基材間鋪設接觸元素。此外，透過比較界面間的剪切應力與界面強度的步驟，來估計複合材料中因施加載重產生之碳管滑移長度。其後，解析模型結果將會與有限元素模型進行驗證與比較。此外，解析模型結果亦與文獻中之實驗數據進行比較與討論。

This research aims to develop a micromechanical stick-slip model to investigate the damping property of carbon nanotube composites. By considering the slip-friction behavior between the CNTs and surround matrix, the energy dissipation mechanism in the composites was characterized in the analytical model. In addition, the effect of aspect ratio of CNTs, interfacial bonding strength, and interfacial friction on the damping behavior of composites were also accounted for in the study. It is noted that the amount of applied cyclic loading on the composites is also an essential factor on the damping behavior, which was also included in the investigation. In addition to the development of micromechanical model, the corresponding finite element analysis was employed to validate the accuracy of the model predictions. A cylindrical FEM model with embedded contract element on the interface between the CNTs and surrounding matrix was created to simulate the contact friction behavior of the CNTs composites. Furthermore, the slip length of the CNTs in the composites in terms of the applied loading was evaluated by comparing the interfacial stress to the interfacial strength through the iteration process. The analytical results and finite element results were then compared with each other. Moreover, the experimental data was also included in the model prediction.