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SUMMARY:Modelling Mechanical Properties of Carbon Nanotube Fibres - Dr Jam
 es Elliot\, Department of Materials Science
DTSTART:20150306T140000Z
DTEND:20150306T150000Z
UID:TALK57041@talks.cam.ac.uk
CONTACT:Ms Helen Gardner
DESCRIPTION:Carbon nanotube (CNT) fibres\, especially if perfect in terms 
 of purity and alignment\, are highly anisotropic. With their very large ax
 ial strengths and stiffnesses\, but ready slippage between the CNTs\, ther
 e is utmost difficulty in transferring an applied load uniformly throughou
 t the fibre. Finite element simulations show that\, in accordance with St 
 Venant’s principle\, very considerable length-to-diameter ratios (> 103)
  are required before the stress becomes uniform\, even at low strains. We 
 discuss several different models for predicting the strength of yarn-like 
 CNT fibers\, and their implications for improving macroscopic fibre proper
 ties. It is proposed that lack of perfect orientation and presence of carb
 onaceous material between bundles greatly enhances the stress transfer\, t
 hus increasing the load carried by fibre before failing in shear. We concl
 ude that the measured strength of CNT fibres depends very much on the spec
 ific testing geometries and that imperfections\, whether by virtue of less
 -than-perfect orientation or of embedded impurities\, are actually major p
 ositive contributors to the observed strength.
LOCATION:Oatley Seminar Room\, Department of Engineering
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