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Computer Simulation of Coiled Carbon Nanotubes Deformation By Molecular Dynamics Approach

Shahini, Ehsan | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45991 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Karimi Taheri, Ali
  7. Abstract:
  8. A Coiled Carbon Nanotube (CCNT) can be geometrically viewed as a graphene sheet whose rolled and twisted to form a helically coiled nanotube. It is the strongest material ever measured with strengthexceeding more than hundred times of steel.The strength of a CCNT iscritically influenced by temperature, tube diameter, strain rate and pitch angle. In this study,a Molecular Dynamics (MD) simulationis performed to understand the effect of temperature, strain rate, tube diameter and pitch angle on the mechanical properties of CCNTs. Results indicate thatexisting the stone-wales defects is necessaryfor thermodynamic stability of CCNTs.According to the stress-strain curves it was observed thatyield stress, yield strain and failure strain decrease with increasing temperature due to increasing the molecular vibration.On the other hand, reducing strain rate results increasing failure strian. Results of force-displacement curves revealed that the spring constant of these materials is highly related to the tube diameter and pitch angle, however temperature and strain rate has little effect on it.Investigating thetoughness results of CCNTs at different temperatures and pitch anglesrepresented that a CCNT (4,4) has higher toughness at lower temperatures and pitch angles. It is also found that calculated toughness of a CCNT (4,4) with a 12.5 degree pitch angle at 100K is more than two hundred times of springlike CNT ropes
  9. Keywords:
  10. Mechanical Behavior ; Molecular Dynamic Simulation ; Carbon Nanotubes ; Tensile Test

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