تحلیل رفتار کمانشی نانولوله‌های کربنی با استفاده از مکانیک مولکولی ساختاری

نوع مقاله: مقاله پژوهشی

نویسندگان

1 عضو هیات علمی / دانشکدة مهندسی هوافضا، دانشگاه صنعتی خواجه نصیرالدین طوسی

2 دانشجوی کارشناسی ارشد / دانشکدة مهندسی هوافضا، دانشگاه صنعتی خواجه نصیرالدین طوسی

چکیده

بروز پدیدة کمانش در شرایط متنوع بارگذاری به ناپایداری سازه می‌انجامد. اساساً بار بحرانی کمانش به عواملی چون هندسه، اندازه، نوع بار و شرایط مرزی بستگی دارد. هدف از نگارش این مقاله، مطالعة اثر ساختار بر رفتار کمانشی نانولوله‌های کربنی است. برای اینکه اثر زاویة کایرال مستقل از اثر اندازه بررسی شود، از هندسه‌هایی با ابعاد برابر و کایرالیتة متفاوت استفاده شده است. برای شبیه‌سازی پیوندهای شیمیایی بین اتم‌های کربن، انرژی پیوند کووالانت کربن - کربن به‌روش مکانیک مولکولی با المان تیر مدل می‌شود. همچنین مختصات گره‌ها به‌وسیلة الگوریتمی ساده تعیین می‌گردد. سپس اثر کایرالیته بر بار کمانش محوری و پیچشی برای انواع ساختارها، با استفاده از روش اجزای محدود تحلیل می‌شود. نتایج مقاله نشان می‌دهد که زاویة‌ کایرال اثر قابل توجهی بر بار کمانش محوری ندارد. اما در بارگذاری پیچشی، ساختار نانولوله تأثیر قابل توجهی بر پایداری آن دارد؛ به‌طوری‌که در شرایط کمانش پیچشی، ساختارهای کایرال ممکن است ضعیف‌تر یا قوی‌تر از ساختارهای متقارن عمل کنند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Analysis of buckling behavior of CNTs using molecular structural mechanics

نویسندگان [English]

  • Mahnaz Zakeri 1
  • Omid Afzalnazhad 2
چکیده [English]

Buckling phenomena in different loading conditions, will lead to structural instability. Critical buckling load is dependent to factors such as geometry, size, load type, and boundary conditions. The aim of this paper is to study of the structure effect on the buckling behavior of carbon nanotubes (CNTs). In order to investigate the effect of chiral angle independent from size effects, all structures are used with the same dimensions but different chiralities. To simulate the chemical bonds between carbon atoms, carbon-carbon covalent bond energy is modeled using molecular mechanics theory and beam element. Coordinates of the nodes are determined using a simple algorithm. Then, chirality effect on axial and torsional buckling load is analyzed using finite element method for different structures. The results of this research show that the chiral angle has no significant effect on critical axial buckling load. However, CNT's structure has considerable influence on the stability. Chiral structures can be weaker or stronger against torsional buckling than symmetric structures.

کلیدواژه‌ها [English]

  • Equivalent Continuum Technique
  • chirality
  • Buckling
  • clock-wise and anti-clock-wise torsion

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