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SUMMARY:Atomistic Simulations of Crack – Microstructure Interactions
DTSTART:20131030T131500
DTEND:20131030T141500
DTSTAMP:20260408T034903Z
UID:d1fec4454b3569e58cc42cadd5ad8e214763ab97381f2ebd5861aadb
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Dr.-Ing. Erik Bitzek\, Friedrich-Alexander-Universität 
 Erlangen-Nürnberg\, Germany\nBio: Erik Bitzek studied physics at the Univ
 ersity of Stuttgart. After his dissertation at the Karlsruhe Institute of 
 Technology he worked as postdoc at the Paul-Scherrer Institute in Switzerl
 and and at the University of Pennsylvania\, USA. Since 2011 he is assistan
 t professor in Germany’s oldest and largest department for materials sci
 ence and engineering at the Friedrich-Alexander-Universität Erlangen-Nür
 nberg.\nHis research interest focuses on the properties of the elementary 
 defects of the crystalline lattice\, which he studies by atomistic simulat
 ion methods. The main objective thereby is to model how the organization a
 nd interaction of these defects influences the mechanical properties of ma
 terials.\nAbstract : The interaction of cracks with constituents of the mi
 crostructure (e.g.\, dislocations\, grain boundaries\, particles or voids)
  is an important factor that determines the brittle or ductile behavior of
  a material. It is for example well known\, that the interaction of pre-ex
 isting dislocations with the crack tip plays a crucial role in crack tip p
 lasticity. The involved mechanisms remain however largely unclear. Here it
  is demonstrated by large-scale 3D atomistic simulations that individual p
 re-existing dislocations may lead to the generation of large numbers of di
 slocations at the crack tip. The simulations revealed fundamentally differ
 ent interaction mechanisms for stationary cracks compared to propagating c
 racks. A detailed analysis of the dislocation – crack interactions allow
 ed to determine which pre-existing dislocations lead to stimulated disloca
 tion emission and multiplication processes and the slip systems they activ
 ate.\nAs an other example of crack – microstructure interaction we studi
 ed fracture along grain boundaries in a bi-crystal set-up. Here\, asymmetr
 ically oriented slip systems lead to different fracture behavior in opposi
 ng crystallographic propagation directions. The simulations show furthermo
 re that even for perfectly brittle fracture\, the fracture toughness can a
 lso depend on the crack propagation direction and can be significantly lar
 ger than the fracture toughness for brittle fracture in single crystals of
  the corresponding orientation. The results are discussed in terms of grai
 n boundary trapping.\nThese examples of crack-microstructure interactions 
 highlight the importance of including atomistic aspects in mesoscale fract
 ure models.
LOCATION:CM 1 104 http://plan.epfl.ch/?room=CM1104
STATUS:CONFIRMED
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