Revised Boundary Conditions for FE-MD Multiscale Coupling of Amorphous Polymers

Ries M, Jain Y, Steinmann P, Pfaller S (2021)

Publication Type: Conference contribution, Abstract of lecture

Publication year: 2021

Original Authors: M. Ries, Y. Jain, P. Steinmann, S. Pfaller

Series: Presentations to VIII Conference on Mechanical Response of Composites

Event location: Online


DOI: 10.23967/composites.2021.014


Due to their versatility, polymer nanocomposites have become an indispensable class of materials in
recent  years.  Classical  simulation  approaches  like  the  Finite  Element  method  (FE)  often  struggle  to
predict  such  composite  materials'  behavior  since  they  cannot  account  for  molecular  effects  taking
place, particularly in the additives' vicinity. To incorporate these effects,  many multiscale formulations
coupling continuum mechanics with particle descriptions have been proposed. One promising
candidate, focusing on amorphous polymers, is the Capriccio Method introduced by Pfaller et al. [1].
They implement a coupling of FE and molecular dynamics (MD) by introducing a handshake region, the
so-called  bridging  domain  where  information  is  transferred  via  virtual  particles.  The  method  has
proved  its  capabilities  in  various  studies,  e.g.,  deriving  nanocomposites'  interphase  properties  [2,3].  
So  far,  the Capriccio  method  relies on  stochastic  boundary  conditions  (SBC) to confine  the  particles
and create a thermodynamic state. However, these SBCs require cutting any protruding molecule and
thus  an  unphysical  change  of  the  microstructure.  To  address  this  problem,  we  extend  the  SBCs  by
adding  an  outer  layer  of  particles  governed  by  the  continuum  deformation  enabling  us  to  generate
coupled  FE-MD  samples  whose  density  matches  a  periodic  MD  solution.  Combining  these  new
boundary conditions with the inelastic extension of the Capriccio method proposed in [4] allows us to
predict amorphous polymers' stress-strain behavior under arbitrary loading accurately. This extension
enhances  the  Capriccio  method's  performance  and  will  be  useful  in  future  studies  of  polymer

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Ries, M., Jain, Y., Steinmann, P., & Pfaller, S. (2021, September). Revised Boundary Conditions for FE-MD Multiscale Coupling of Amorphous Polymers. Paper presentation at VIII Conference on Mechanical Response of Composites, Online.


Ries, Maximilian, et al. "Revised Boundary Conditions for FE-MD Multiscale Coupling of Amorphous Polymers." Presented at VIII Conference on Mechanical Response of Composites, Online 2021.

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