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A micro mechanical study on tensile behavior of steel sheets with spheroidal cementite using crystal plasticity finite element method
, Article Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications ; Volume 236, Issue 12 , 2022 , Pages 2357-2371 ; 14644207 (ISSN) ; Assempour, A ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
In this research, we investigate the effects of various microstructural features on the behavior of spherical steel sheets, using the crystal plasticity finite element method. The cementite phase ratio, the grain sizes of ferrite and cementite, and the percentage of residual pearlite in the steel structure due to incomplete annealing are the major microstructural parameters studied in this work. A grain generator software has been developed to generate hexagonal ferrite grains as well as circular cementite particles distributed in the ferrite matrix. We use a hard coating with special properties as an intermediate layer around the cementite grains to simulate the contact between ferrite...
Mechanical behavior of spheroidized steel sheets: effects of microstructural features, loading, and boundary condition modeling
, Article Journal of Materials Engineering and Performance ; Volume 32, Issue 14 , 2023 , Pages 6350-6364 ; 10599495 (ISSN) ; Assempour, A ; Sharif University of Technology
Springer
2023
Abstract
In this study, the effects of the microstructural features on the mechanical behavior of the spheroidal steel sheets are investigated. The crystal plasticity finite element method is used for simulations. For this purpose, a 2D preprocessing and grain generator software was developed. A series of representative volume elements (RVEs) with different microstructures and boundary conditions were produced. The hardening parameters in the simulations are calibrated according to the available experimental data in the literature. Then, the flow behaviors of the steel sheets under uniaxial tensile load and pure shear were extracted, and the effects of cementite particle fraction and size on steel...
Application of Inverse Finite Element in Tube Hydroforming
, M.Sc. Thesis Sharif University of Technology ; Assempour, Ahmad (Supervisor)
Abstract
The inverse Finite Element method (IFEM) has been used for estimation of the initial length of tube, axial feeding and fluid pressure in tube hydroforming. The already developed IFEM algorithm, which has been used in this work, is based on the total deformation theory of plasticity. Although the nature of tube hydroforming is three-dimensional deformation, a technique has been used to perform the computations in two-dimensional space. Therefore, compared with conventional forward finite element methods, the present computations are quite fast with no try and error process. The solution provides all the components of strain. Using the forming limit diagram (FLD), the components of strain can...
A New Method Based on Crystal Plasticity Finite Element to Predict the Formability of Steel Sheets with Spheroidal Cementites
, Ph.D. Dissertation Sharif University of Technology ; Assempour, Ahmad (Supervisor)
Abstract
In this research, using the crystal plasticity finite element method, the effects of various microstructural features on behavior of spherical steel sheets have been investigated. The cementite phase ratio, the grain sizes of ferrite and cementite, and the percentage of residual pearlite in the steel structure due to incomplete annealing are the major microstructural parameters studied in this work. A grain generator software has been developed to generate ferrite grains as well as cementite particles distributed in the ferrite matrix. A hard coating with special properties as an intermediate layer around the cementite grains has been considered to simulate the contact between ferrite grains...
Application of inverse finite element method in tube hydroforming modeling
, Article Applied Mathematical Modelling ; Volume 37, Issue 8 , 2013 , Pages 5913-5926 ; 0307904X (ISSN) ; Shirin, M. B ; Assempour, A ; Sharif University of Technology
2013
Abstract
In tube hydroforming, the inverse finite element method (IFEM) has been used for estimating the initial length of tube, axial feeding and fluid pressure. The already developed IFEM algorithm used in this work is based on the total deformation theory of plasticity. Although the nature of tube hydroforming is three-dimensional deformation, in this paper a modeling technique has been used to perform the computations in two-dimensional space. Therefore, compared with conventional forward finite element methods, the present computations are quite fast with no trial and error process. In addition, the solution provides all the components of strain. Using the forming limit diagram (FLD), the...
A different approach to estimate the process parameters in tube hydroforming
, Article International Journal of Material Forming ; Volume 8, Issue 3 , July , 2015 , pp 355-366 ; ISSN: 19606206 ; Shirin, M. B ; Einolghozati, M ; Assempour, A ; Sharif University of Technology
2015
Abstract
An enhanced unfolding inverse finite element method (IFEM) has been used together with an extended strain-based forming limit diagram (FLD) to develop a fast approach to predict the feasibility of tube hydroforming process of concept part and determine where the failure or defects can occur. In tube hydroforming, the inverse IFEM has been used for estimating the initial length of tube, axial feeding and fluid pressure. The already developed IFEM algorithm used in this study is based on the total deformation theory of plasticity. Although the nature of tube hydroforming is three-dimensional deformation, in this article a modeling technique has been used to perform the computations in...