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SUMMARY:Mechanics of Architected Materials Across Length and Time Scales -
  Prof Carlos M Portela\, School of Engineering\, MIT
DTSTART:20220225T140000Z
DTEND:20220225T150000Z
UID:TALK169727@talks.cam.ac.uk
CONTACT:46601
DESCRIPTION:Ferroelectric ceramics exhibit a spontaneous electric polariza
 tion that can be reversed under the application of an electrical or mechan
 ical loading. The macroscopic features of polarization switching derive\, 
 at the mesoscale\, from the nucleation and growth of domains of constant p
 olarization (these domains correspond to the different variants of the cry
 stallographic phase).  Simulations of the evolution of polarization domain
 s are based on diffuse-interface models (also called phase-field models) w
 here the electro-mechanical fields evolve steeply but continuously across 
 domain walls. Existing  diffuse-interface models are based on the Allen-Ca
 hn equation which assumes\, unlike experimental evidence\, a linear relati
 on between the velocity of domain walls and their conjugate driving force.
  Therefore\, while the Allen-Cahn model provides appropriate modelling of 
 polarization switching in the quasistatic regime\, it fails to capture rat
 e effects involved in fast-switching experiments. In this work\, we develo
 p an alternative phase-field formulation that accounts for the non-linear 
 kinetics of domain walls and discuss its possibilities for modeling the st
 ep load response of ferroelectrics as well as the effects of electrical lo
 ading rate.
LOCATION:Zoom Meeting ID: 898 3752 1667
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