STRESS DISTRIBUTION IN NANOTUBES

Yogesh Bansod — Tue, 07 Oct 2008 04:09:19 -0400

(All my simulations and research is conducted under guidance of respected Dr. Henry Tan, Uni. of Manchester)

STRESS DISTRIBUTION IN NANOTUBES

Nanotubes are long tiny cylinders of graphite structure with caps at each end. Carbon nanotubes have large interfacial area per volume and hold extraordinary mechanical, electrical as well as thermal properties.The length to diameter ratio also called as aspect ratio plays an vital role in describing the efficiency of nanotubes as reinforced material. For better mechanical load transfer the surface area of the fibre should be more which is provided by carbon nanotubes.

When an unidirectional nanotubes reinforced polymer is subjected to a tensile load in the nanotubes i.e. in fibres direction, then stress transfers from the polymer matrix to the nanotubes by shear stress at the interface of nanotubes and polymeric matrix .The source of the interfacial shear stress is the difference between deformations of nanotubes and the polymer matrix surrounding it. The interfacial shear stress acts in the longitudinal direction of the nanotubes around its periphery.

In case of normal stress distribution in nanotubes fibres are considered, the axial stress increases gradually from its ends and reaches to a maximum value at the central part represents special feature of long nanotube fibre. The reason behind this is, as unlike conventional fibre reinforced polymer composites, large interfacial areas are available for the load transfer in carbon nanotubes reinforced composites due to the high aspect ratio of carbon nanotubes.

In addition to this, maximum shear stress is maximum/highest near the fibre ends but it reduces rapidly to near zero value or almost negligible value towards the mid-length of the nanotubes. This nature of shear stress distribution is totally opposite to normal stress distribution in long nanotubes fibres. The concentration of shear stress is limited to a very small nano-size region, which seems to be a beneficial characteristic of nanotubes.

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STRESS DISTRIBUTION IN NANOTUBES