Yazar "Guder, Vildan" seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim Yok
    Öğe
    A Computational Model of Cd2+ Doped Fluorapatite Ca10(PO4)6F2 Biomaterial by Molecular Dynamics Simulations
    (Elsevier, 2020) Guder, Vildan; Dalgic, Serap Senturk
    We have presented a computational model studied with the Cd2+ ions doped hexagonal fluorapatite (FAP), Ca-10(PO4)F-2 by classic molecular dynamics (MD) simulations using the general utility lattice program (GULP). The potential model has included long-range Coulomb interactions, general three-body, Buckingham and spring (core-shell) interatomic potentials. The Cd2+ ions have substituted into the Ca2+ sublattice of FAP. The structure optimization calculations are carried out for each composition of CdxCa10-x(PO4)F-2 (x=1-9) by minimizing the energy of the system. We have predicted lattice parameters, density, bulk modulus and elastic constants of new stoichiometric apatites. The computed results are compared with available experimental data and those obtained by other methods [1]. We have concluded that those interatomic potentials can be applied to Cd2+ ions doped mineral apatites. The developed computing model may provide a useful method in understanding and design of new biomaterials. (C) 2017 Elsevier Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Key factors of deformation mechanism of Cu-Ag alloy
    (Elsevier, 2022) Sengul, Sedat; Guder, Vildan
    This work focused on the effect of the structural order and dimensionality on the deformation mechanism of Cu-Ag alloy and the triggering factors of this mechanism. It is revealed that (i) the weakness of the system develops from bulk to nanoscale and crystalline to amorphous systems, (ii) Cu-Ag nanowires are more flexible than their bulk counterparts, (iii) crystalline Cu-Ag alloys are stiffer than amorphous systems. The reason for early yielding and less stiffness of amorphous Cu-Ag nanowire with respect to bulk material is the less fraction of ideal icosahedra. Cu atoms are a key factor to characterize the mechanical response of both amorphous Cu-Ag alloys. While there are two different deformation modes in crystalline systems, the only mode observed in the amorphous alloy is homogeneous deformation. The presence of (0,5,2,x) (x = 5,6) polyhedral is the reason for the transition of deformation from homogeneous to inhomogeneous in the crystalline Cu-Ag alloys.
  • Küçük Resim Yok
    Öğe
    Surface effects on the mechanical properties of rhodium nanowires by molecular dynamics simulations
    (Elsevier, 2021) Sengul, Sedat; Guner, Alper Koray; Guder, Vildan
    This study comprehensively investigates the mechanical properties of rhodium (Rh) nanowires using molecular dynamics simulations in which the interactions were expressed by embedded atom method potentials and interprets their relation with the deformation process. We have observed that the stress-strain behavior of Rh nanowires is radically different from the bulk material. As the size increased, the Elastic Modulus of nanowires gradually decreases and saturates to reach bulk value. It is revealed that the mechanical response of thicker nanowires than the critical value of 2.8 nm size is characterized by the core atoms and the surface effects lose their dominance due to the stability of the core atoms. The high strain rates delay yielding and neck formation and can be used to design the strengthened thin Rh nanowires.
  • Küçük Resim Yok
    Öğe
    Tensile strength and failure mechanism of hcp zirconium nanowires: Effect of diameter, temperature and strain rate
    (Elsevier, 2020) Guder, Vildan; Sengul, Sedat
    This study is a comprehensive analysis to demonstrate the deformation and failure mechanism of hexagonal Zr nanowires in [0 0 0 1] orientation. Molecular dynamics simulations in conjunction with embedded atom potentials are utilized to determine the effect of the temperature, diameter and strain rate on mechanical properties of nanowire. We have observed two basic scheme that these parameters have different impacts on elastic and plastic deformations of Zr nanowires. The elastic response of nanowire increases by high strain rate, low temperature and small diameter. Although Young's Modulus can be characterized by strain rate, the temperature and the diameter are more effective key variables in engineering of strength mechanism. On the other hand, high strain rate, low temperature and large diameter decrease the failure of Zr nanowires.