research

Dear all,

An update on the http://www.legato-team.eu at work in the COVID19 response in Luxembourg. 

Check out http://www.ariana-tech.com a joint venture between Kyoto and Luxembourg. 

We study the nature of an environment-induced exceptional point in a non-Hermitian pair of coupled mechanical oscillators. The mechanical oscillators are a pair of pillars carved out of a single isotropic elastodynamic medium made of aluminum and consist of carefully controlled differential losses. The interoscillator coupling originates exclusively from background modes associated with the “environment,” that portion of the structure which, if perfectly rigid, would support the oscillators without coupling.

Achieving high damping and stiffness is challenging in common materials because of their inter-dependent scaling. Controlling extreme mechanical waves requires synergistically enhanced damping and stiffness. We demonstrate superior damping and stiffness in vertically aligned carbon nanotube (VACNT) foams that are also independently controllable by exploiting their synthesis-tailored structural hierarchy and structural gradients. They exhibit frequency- and amplitude-dependent responses with dramatically tunable dynamic stiffness while maintaining constant damping.

Distinct deformation mechanisms that emerge in nanoscale enable the nanostructured materials to exhibit outstanding specific mechanical properties. Here, we present superior microstructure- and strain-rate-dependent specific penetration energy (up to ∼3.8 MJ/kg) in semicrystalline poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) thin films subjected to high-velocity (100 m/s to 1 km/s) microprojectile (diameter: 9.2 μm) impacts.

EML Webinar on May 13, 2020 will be given by Prof. Katia Bertoldi at Harvard University via Zoom meeting. 

Title: Multistable structures - from energy trapping to morphing

Time: 7 am California, 10 am Boston, 3 pm London, 10 pm Beijing on May 13, 2020

Zoom Link: https://harvard.zoom.us/j/271079684 

Zoom ID: 271 079 684

We present a singularity free formulation and its efficient numerical implementation for the spatial deformation of Kirchhoff rods having uniformly distributed electrostatic charge. Due to the presence of continuously distributed charge, the governing equations of the Kirchhoff rod become a system of integro-differential equations which is singular at every arc-length. We show that this singularity is of removable type which, ones removed, makes the system well defined everywhere. No cutoff length or mollifier is used to remove this singularity.

https://doi.org/10.1016/j.jmps.2020.104017

Abstract

The full paper can be found at:

https://authors.elsevier.com/c/1b2plc7qwXwm0

Abstract:

Geometric incompatibilities are ubiquitous in natural structures and are recently being exploited in synthetic

structures to enhance the performance of soft systems. In this work we focus on infinitely long bi-layer

neo-Hookean tubes with radial incompatibilities, i.e. the outer radius of the inner tube is different than the inner

Dexin Zhao , Kelvin Xie 

Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA.

Abstract

The full video of a recent symposium organized by the Young Academy of Europe on Covid-19 epidemiology is now online on YouTube, see: https://www.youtube.com/watch?v=Sy1qVBs6fHI