Computational modelling of fracture and dislocations

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en Szelestey, Peter 2012-02-17T06:43:44Z 2012-02-17T06:43:44Z 2005-02-04
dc.identifier.isbn 951-22-7500-7
dc.identifier.issn 1455-0474
dc.description.abstract Mechanical properties of solids bear great significance because of their importance in various fields of engineering and materials science. Fracture and plasticity are the two characteristic mechanisms by which materials permanently deform under external loading. Beside experiments and theoretical model calculation computational modelling greatly contributes to the understanding of these phenomena. This dissertation consists of various studies of topics related to these fields. First, the branching instability of dynamic fracture is studied in a simple lattice model which describes a brittle material at mesoscopic length-scales. It is shown that the presence of anisotropy leads to a variation in the fracture pattern and crack tip velocity oscillations. The second part of the thesis consists of atomic level computational modelling of dislocations using molecular dynamics method. Here, the interatomic potential plays a definite and relevant role. For that reason a semi-empirical, many-body embedded-atom potential is developed which turns out to be especially suitable for dislocation studies in fcc crystals, because of the realistic stacking-fault energies it predicts. Dislocation properties at the atomic level determine the micro-structure and in turn the plastic properties of materials. The static dislocation core structure is determined for dissociated dislocations in nickel and compared to analytical calculations. Furthermore, the effective Peierls stress, characterizing the dislocation mobility, and the variation in the dislocation structure through its motion is investigated for the screw orientation as a function of the separation distance of partials. Finally, the interaction of a dissociated screw dislocation and a vacancy type stacking-fault tetrahedron is studied. A wide variety of dislocation processes are found including bending and jog line formation, depending on the internal structure of the dislocation, the orientation and position of the defect. en
dc.format.extent 51, [58]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Helsinki University of Technology Laboratory of Computational Engineering publications. Report B en
dc.relation.ispartofseries 45 en
dc.relation.haspart Szelestey P., Heino P., Kertész J. and Kaski K., 2000. Effect of anisotropy on the instability of crack propagation. Physical Review E 61, number 4, pages 3378-3383.
dc.relation.haspart Perondi L., Szelestey P. and Kaski K., 2000. Structure of a dissociated edge dislocation in copper. Materials Research Society Symposium Proceedings 578, pages 223-228.
dc.relation.haspart Szelestey P., Patriarca M., Perondi L. and Kaski K., 2002. Modified EAM potentials for modelling stacking-fault behavior in Cu, Al, Au, and Ni. International Journal of Modern Physics B 16, number 19, pages 2823-2835.
dc.relation.haspart Szelestey P., Patriarca M. and Kaski K., 2003. Computational study of core structure and Peierls stress of dissociated dislocations in nickel. Modelling and Simulation in Materials Science and Engineering 11, number 6, pages 883-895.
dc.relation.haspart Szelestey P., Patriarca M. and Kaski K., 2005. Dissociated dislocations in Ni: a computational study. Materials Science and Engineering A 390, numbers 1-2, pages 393-399.
dc.relation.haspart Szelestey P., Patriarca M. and Kaski K., Computational study of a screw dislocation interacting with a stacking-fault tetrahedron. Modelling and Simulation in Materials Science and Engineering, submitted for publication.
dc.subject.other Materials science en
dc.title Computational modelling of fracture and dislocations en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Electrical and Communications Engineering en
dc.contributor.department Sähkö- ja tietoliikennetekniikan osasto fi
dc.subject.keyword branching instability en
dc.subject.keyword molecular dynamics en
dc.subject.keyword EAM potential en
dc.subject.keyword dislocation core structure en
dc.subject.keyword Peierls stress en
dc.subject.keyword dislocation-defect interaction en
dc.identifier.urn urn:nbn:fi:tkk-004691
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Laboratory of Computational Engineering en
dc.contributor.lab Laskennallisen tekniikan laboratorio fi

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