نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی دکترا، مهندسی مکانیک، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران

2 استاد، مهندسی مکانیک، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران

3 استادیار، مهندسی و علم مواد، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران

چکیده

در این مقاله خواص الاستوپلاستیک یک نانوکامپوزیت پلیمری با تکیه بر تعدادی از عوامل مقیاس مزو مورد بررسی قرار گرفته است. برای این منظور از ترکیب روش اجزای محدود با میکرومکانیک استفاده شده است. با توجه به ماهیت پیوند ناکاملِ نانولوله و ماتریس، برای جایگزین کردن نانولوله و ناحیه­ی مشترک با یک تک‌رشته­ی توپر، از روش چندمقیاسی اجزای محدود استفاده شده است. سپس با استفاده از روش میدان میانگین موری- تاناکا، منحنی‌های تنش-کرنش نانوکامپوزیت استخراج و با استفاده از آن، تأثیر زاویه­ی قرارگیری نانولوله بر مدول یانگ، تأثیر طول نانولوله بر خواص الاستوپلاستیک و تأثیر کلوخه شدن نانولوله‌ها بر رفتار الاستوپلاستیک بررسی شده است. همچنین با بررسی طول نانولوله‌ها مشخص شد که نانولوله‌های دارای طول 10 تا 300 نانومتر، تأثیر قابل توجهی بر سفتی نانوکامپوزیت دارد، درحالی‌که تأثیر طول‌های کوتاه‌تر و بلندتر چندان قابل توجه نیست. همچنین، با صرفنظر از کلوخه شدن، افزایش کسر حجمی نانولوله‌ها منجر به افزایش سفتی نانوکامپوزیت می‌گردد. این در حالی است که کلوخه شدن نانولوله‌ها، منجر به کاهش سفتی نانوکامپوزیت می‌شود. تأثیر منفی این پدیده به‌حدی است که در برخی موارد، افزایش کسر حجمی نه‌تنها باعث افزایش سفتی نانوکامپوزیت نمی‌شود، بلکه آن را کاهش می‌دهد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Investigation of nanotubes’ length and their agglomeration effects on the elastoplastic behavior of polymer-based nanocomposites

نویسندگان [English]

  • Majid Karimi 1
  • Rahmatollah Ghajar 2
  • Abbas Montazeri 3

1 - Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran

2 Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran

3 Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran

چکیده [English]

In this article, elastoplastic properties of polymeric nanocomposites embedded with carbon nanotubes (CNTs) are explored with emphasis on the meso-scale phenomena. To this end, a combination of finite element method and micromechanics is implemented. Accordingly, at first, considering the non-bonded nature of nanotube/polymer interactions, a multiscale finite element method is employed to replace the matrix, CNT, and polymer atoms neighboring it with a perfectly bonded equivalent nanofiller. Subsequently, nanocomposite stress-strain curves are extracted based on the mean field homogenization approach. Using this model, the effects of CNTs orientation and their agglomeration on the mechanical behavior of nanocomposite samples are thoroughly studied. Moreover, it is found that to have an efficient reinforcing effect, the CNT length should be greater than 10 nm. On the other hand, it can be concluded that there is an optimum value of this parameter (i.e. 300 nm) above which, there is no any extra stiffening effect. Furthermore, regarding the CNTs agglomeration, it is revealed that although, theoretical investigations show that increasing CNT volume fraction(VF) leads to an increase in the stiffness, occurring this phenomenon can have a deteriorative role in terms of influencing the mechanical behavior of these nanocomposites at higher VFs.

کلیدواژه‌ها [English]

  • Polymeric Nanocomposite
  • Stress-strain curve
  • Agglomeration
  • Nanotube length
  • Orientation

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