Researcher:
Mirzajanzadeh, Morad

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PhD Student

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Morad

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Mirzajanzadeh

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Mirzajanzadeh, Morad

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2014 - 20183

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Researcher Of Publications: search.filters.isAuthorOfPublication.8756f0d0-b9ea-434c-8c06-bd9350c13039

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    A microstructure-sensitive model for simulating the impact response of a high-manganese austenitic steel
    (Asme, 2016) N/A; N/A; Department of Mechanical Engineering; Mirzajanzadeh, Morad; Canadinç, Demircan; PhD Student; Faculty Member; Department of Mechanical Engineering; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Engineering; N/A; 23433
    Microstructurally informed macroscopic impact response of a high-manganese austenitic steel was modeled through incorporation of the viscoplastic self-consistent (VPSC) crystal plasticity model into the ANSYS LS-DYNA nonlinear explicit finite-element (FE) frame. Voce hardening flow rule, capable of modeling plastic anisotropy in microstructures, was utilized in the VPSC crystal plasticity model to predict the micromechanical response of the material, which was calibrated based on experimentally measured quasi-static uniaxial tensile deformation response and initially measured textures. Specifically, hiring calibrated Voce parameters in VPSC, a modified material response was predicted employing local velocity gradient tensors obtained from the initial FE analyses as a new boundary condition for loading state. The updated micromechanical response of the material was then integrated into the macroscale material model by calibrating the Johnson-Cook (JC) constitutive relationship and the corresponding damage parameters. Consequently, we demonstrate the role of geometrically necessary multi-axial stress state for proper modeling of the impact response of polycrystalline metals and validate the presented approach by experimentally and numerically analyzing the deformation response of the Hadfield steel (HS) under impact loading.
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    Microstructure-based modeling of the impact response of a biomedical niobium-zirconium alloy
    (Cambridge University Press (CUP), 2014) Maier, Hans J.; N/A; N/A; N/A; N/A; Department of Mechanical Engineering; Önal, Orkun; Bal, Burak; Toker, Sıdıka Mine; Mirzajanzadeh, Morad; Canadinç, Demircan; PhD Student; PhD Student; PhD Student; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 255504; N/A; 23433
    This article presents a new multiscale modeling approach proposed to predict the impact response of a biomedical niobium-zirconium alloy by incorporating both geometric and microstructural aspects. Specifically, the roles of both anisotropy and geometry-based distribution of stresses and strains upon loading were successfully taken into account by incorporating a proper multiaxial material flow rule obtained from crystal plasticity simulations into the finite element (FE) analysis. The simulation results demonstrate that the current approach, which defines a hardening rule based on the location-dependent equivalent stresses and strains, yields more reliable results as compared with the classical FE approach, where the hardening rule is based on the experimental uniaxial deformation response of the material. This emphasizes the need for proper coupling of crystal plasticity and FE analysis for the sake of reliable predictions, and the approach presented herein constitutes an efficient guideline for the design process of dental and orthopedic implants that are subject to impact loading in service.
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    A novel approach for monitoring plastic flow localization during in-situ sem testing of small-scale samples
    (Springer, 2018) Niendorf, Thomas; Weidner, Anja; N/A; Department of Mechanical Engineering; Mirzajanzadeh, Morad; Canadinç, Demircan; PhD Student; Faculty Member; Department of Mechanical Engineering; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Engineering; N/A; 23433
    A novel method is proposed for monitoring the plastic flow localization during in-situ scanning electron microscopy (SEM) testing of small-scale AISI 316 L stainless steel. Stress-strain behavior of the material was obtained using a hybrid numerical-experimental (HNE) approach. By repeatedly illustrating each pair of sequentially taken SEM surface images throughout the deformation history in alternating order in form of a video, location of the material points which are not moving during the deformation can be detected. At the initial stages of deformation these points are located on the geometrical symmetry line of the test sample, however; when uniform straining limit of the material is reached, the locations of the stationary material points reveal the plastic localization regions. The current results clearly prove the feasibility of the presented method in monitoring primary plastic localization events through in-situ SEM tensile testing.