I. Arias and M. Arroyo, Size-Dependent Nonlinear Elastic Scaling of Multiwalled Carbon Nanotubes, Phys. Rev. Lett. 100, 085503 (2008).

Size matters for the mechanics of multiwalled carbon nanotubes (MWCNTs). It has been known for some time that MWCNTs often wrinkle under deformation exhibiting the so-called rippling deformation pattern, which makes MWCNTs much softer. Through large-scale multiscale simulations we have characterized with a power law the softer wrinkled response, and showed that the transition strain between the super-stiff behavior attributed to MWCNTs and this softer regime scales as the inverse of the tube diameter. Thus, the tera Pascal Young’s modulus can be fully exploited in devices and materials only for moderately sized tubes. Similarly, in interpreting experiments or designing devices, the classical Euler-Bernouilli beam theory can only be applied to such tubes. The elasticity of thicker tubes is nonlinear, typically display mixtures of wrinkled and unwrinkled sections, and often exhibit hysteretic mechanical behavior.

See http://imechanica.org/node/2395 for a related post.

Two four-year doctoral fellowships at the LaCàN Research group (http://www-lacan.upc.es/), Universitat Politècnica de Catalunya (UPC, Barcelona, Spain).

These two fellowships, funded by the Spanish Ministry of Science and Education ("beca FPI"), coverfull tuition, a monthly stipend and provide funds for short international research stays. The starting date is expected in the Summer-Fall 2008.

Dear colleagues, 

I would like to share the following paper, in press in the Journal of the Mechanics and Physics of Solids. It can be found at the publisher's web at

 http://dx.doi.org/10.1016/j.jmps.2007.10.001

 A preprint is also attached below.

Abstract

Dear iMechanica colleagues,

I would like to announce that Matlab routines implementing the maximum-entropy approximation schemes presented in

Marino Arroyo and Michael Ortiz, “Local maximum-entropy approximation schemes: a seamless bridge between finite elements and meshfree methods”, International Journal for Numerical Methods in Engineering, 65:2167–2202 (2006).

can be downloaded from