A Study on Fatigue Property of CNT/Epoxy Resin Composite Materials (III)

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Project title

Code/計畫編號

NSC99-2221-E019-056

Translated Name/計畫中文名

碳奈米管/環氧樹脂複合材料疲勞性質之研究 (III)

Project Coordinator/計畫主持人

Yi-Ming Jen

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Mechanical and Mechatronic Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=2118926

Year

2010

Start date/計畫起

01-08-2010

Expected Completion/計畫迄

31-07-2011

Bugetid/研究經費

782千元

ResearchField/研究領域

材料科技

本計畫於前兩年度將完成在不同溫濕度條件下，具備不同碳奈米管改質條件及不同碳奈米管含量的碳奈米管/環氧樹脂複合材料基本及累積疲勞性質研究。本計畫第三年度的研究重點在於考量結構中常有圓孔、導角、溝槽等應力集中狀況或是因為製程或負載而出現裂縫出現，如果能針對碳奈米管/ 環氧樹脂複合材料，在不同溫濕度環境下有效掌握其應力集中效應對疲勞強度的影響以及疲勞裂縫成長的特性，將有助於此類新興材料的工程設計與應用。因此，本年度（第三年）計畫將在前兩年度研究成果之基礎上，結合實驗及理論分析的方式，研究在不同溫濕度環境中，缺口效應對於改質後碳奈米管/環氧樹脂複合材料疲勞強度之影響；並測定其疲勞裂縫成長速率與裂縫前端應力強度因子範圍之間的關係。在實驗及理論分析中，溫濕度條件以及碳奈米管含量將是研究所探討的變數。在本計畫第三年度中之研究方法及步驟可分為兩大部分：第一部份是在不同溫濕度條件下，針對不同碳奈米管含量及不同缺口尺寸的奈米複材缺口試片進行疲勞實驗；並以數學模型來描述缺口試片的疲勞壽命曲線。得到的缺口試片之疲勞壽命曲線將與本計畫第一年度所獲得之無缺口試片疲勞壽命曲線相比較，藉此找出碳奈米管/環氧樹脂複合材料的疲勞缺口因子及缺口敏感度。此疲勞缺口因子及缺口敏感度預期將與溫濕度條件、碳奈米管含量及缺口尺寸等實驗參數有關。缺口敏感度的測定將對於具應力集中效應的碳奈米管/環氧樹脂複合材料結構之疲勞設計有重要的幫助。第二部份則是在不同溫濕度條件下，利用不同碳奈米管含量的碳奈米管/環氧樹脂複合材料製作 CT 試片（Compact Tension Specimen），進行疲勞裂縫成長速率的測量實驗；並以數學模型來描述穩定狀況下疲勞裂縫成長速率及應力強度因子範圍之間的關係。此數學關係中之相關參數預期將與溫濕度條件及碳奈米管含量等實驗參數有關。此疲勞裂縫成長速率的研究結果將可對於承受動態負荷之具裂縫之碳奈米管/環氧樹脂複合材料結構提供重要的設計依據。此部分的成果亦可被應用在具裂縫奈米複材結構的裂縫成長壽命預估及修補設計之上。"In the past two years of this project, the basic and cumulative fatigue behavior of the carbon nanotube (CNT)/epoxy composites has been experimentally investigated. The effects of environments, contents of CNTs and the modification of CNTs on the fatigue strength of the studied nanocomposites have been also evaluated in the project. Because notches and cracks/defects due to the manufacturing and application are frequently existed in the engineering components, the knowledge of the stress concentration effect and the crack behavior on the innovative material are necessary in the design and application of these nanocomposites. Hence, the goal of this project in the next year is to analyze experimentally the notch effect on the fatigue strength of the studied nanocomposites and the fatigue crack growth behavior of these composites. The research work in the third year includes two main parts. The first part of the project is to study the notch effect on the fatigue strength of the CNT/Epoxy composites. The temperature/humidity condition, contents of CNTs and sizes of notches are the considered variables in the study. The stress-life curves for the notched specimens will be experimentally established and expressed using specific mathematical models. The material constants in these models will be dependent on the experimental variables. Furthermore, by integrating with the smooth-specimen data achieved in the first year of this project, the fatigue notch factors and the notch sensitivity for the nanocomposites can be obtained. These experimental and analytical results will be helpful in the fatigue design for the notched nanocomposite structures. The second part of this research is to investigate the crack growth rates for the studied nanocomposites using the compact tension specimens. Similarly, the temperature/humidity condition and contents of CNTs are the variables in the experiments. The stable relationship between the crack propagation rates and the stress intensity factor ranges will be obtained experimentally and described using mathematical models. The material constants will be also dependent on the considered variables. These models will be expected to be useful in the remaining fatigue-life prediction and repair design of the pre-cracked structures."

Keyword(s)

碳奈米管/環氧樹脂複合材料
疲勞
缺口
疲勞缺口因子
缺口敏感度
疲勞裂縫成長速率
應力強度因子
carbon nanotube/epoxy composite
fatigue
notch
fatigue notch factor
notch sensitivity
fatigue crack propagation rate
stress intensity factor

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A Study on Fatigue Property of CNT/Epoxy Resin Composite Materials (III)

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