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Papers by mehdi shahzamanian

Research paper thumbnail of Study of forming limit diagram (FLD) prediction of anisotropic sheet metals using Gurson model in M-K method

International Journal of Material Forming, 2021

Research paper thumbnail of Transient and thermal contact analysis for the elastic behavior of functionally graded brake disks due to mechanical and thermal loads

Materials and Design, 2010

In this paper, the transient and contact analysis of functionally graded (FG) brake disk is prese... more In this paper, the transient and contact analysis of functionally graded (FG) brake disk is presented. The analysis was carried out using ANSYS parametric design language (APDL). The FG brake disk is made of metal-ceramic material. The material properties vary in radial direction with the values from full-metal at the inner radius to that of full-ceramic at the outer radius. In the analysis, FG brake disk is in contact with one pure pad disk and coulomb contact friction is considered as heat source. The non-dimensional results are obtained for specific value of grading index (n = 1) by considering different material property divisions of 25, 50, 100 and 200. The results presented are for the pressure distribution, total stress, pad penetration, friction stress, heat flux and temperature during contact, for different values of contact stiffness factor, Fkn, which depends on the property gradation of FG brake disk with 200 material property divisions. The results show that the contact pressure and contact total stress increase with increasing values of Fkn, and hence it can be concluded that gradation of the metal-ceramic has significant effect in the thermomechanical response of FG brake disks.

Research paper thumbnail of Elastic Contact Analysis of Functionally Graded Brake Disks Subjected to Thermal and Mechanical Loads

International Journal for Computational Methods in Engineering Science and Mechanics, 2013

In this paper, finite element contact analysis of a functionally graded (FG) brake disk in contac... more In this paper, finite element contact analysis of a functionally graded (FG) brake disk in contact with a pad, subjected to rotation, contact pressure, and frictional heat, is presented. The material properties vary through the thickness according to a power-law characterized by a grading index, n. The contact surfaces are full-ceramic with full-metal free surface. The effects of n on the displacement, contact status, strain and stress are investigated. From the analysis, thermo-elastic and contact results are extremely dependent on n. Hence, n is an important criteria for the design of FG brake disks for automotive and aircraft applications.

Research paper thumbnail of The effect of superimposed hydrostatic pressure on shear decohesion in round bar tensile specimens

International Journal of Fracture, 2022

Research paper thumbnail of Finite element analysis of elastic–plastic and fracture behavior in functionally graded materials (FGMs)

The effect of material property variation on ductility and fracture strain in functionally graded... more The effect of material property variation on ductility and fracture strain in functionally graded materials (FGMs) is investigated using the finite element method (FEM) and the Gurson–Tvergaard–Needleman (GTN) model, which is strain-controlled for void nucleating. The material properties of FGMs in the tensile tests are assumed to be represented by a power-law distribution in the thickness direction. A gradation index (n) assigns the material property distribution. The lower and upper surfaces are pure hard (n = ∞) and pure soft (n = 0) materials, respectively, in the simulations. The ductility and fracture strain changes with varying gradation index. The development of stress triaxiality slows down in FGMs, and the total void volume fraction is reduced. The analysis is performed for five values of n, and the results are discussed numerically. The aim of this study is to help the researchers for better design and fabrication of FGMs. The necking strain in FGMs is calculated and it i...

Research paper thumbnail of Study of Influence of Width to Thickness Ratio in Sheet Metals on Bendability under Ambient and Superimposed Hydrostatic Pressure

Applied Mechanics

The effect of the width to thickness ratio on the bendability of sheet metal is investigated usin... more The effect of the width to thickness ratio on the bendability of sheet metal is investigated using the finite element method (FEM) employing the Gurson–Tvergaard–Needleman (GTN) model. Strain path changes in the sheet with change in the width/thickness ratio. It is shown that bendability and fracture strain increase significantly by decrease in the width/thickness ratio. The stress state is almost uniaxial when the stress ratio (α) is close to zero for narrow sheets. Stress ratio is nothing but the major stress to minor stress ratio. This delays the growth and coalescence of micro-voids as the volumetric strain and stress triaxiality (pressure/effective stress) decrease. On the other hand, ductility decreases with increase in α for wider sheets. Fracture bending strain is calculated and, as expected, it increases with decrease in the width/thickness ratio. Furthermore, a brief study is performed to understand the effect of superimposed hydrostatic pressure on fracture strain for var...

Research paper thumbnail of Representative volume element based modeling of cementitious materials

The current work focuses on evaluation of the effective elastic properties of cementitious materi... more The current work focuses on evaluation of the effective elastic properties of cementitious materials through a voxel based finite element analysis (FEA) approach. Voxels are generated for a heterogeneous cementitious material (type-I cement) consisting of typical volume fractions of various constituent phases from digital microstructures. The microstructure is modeled as a microscale representative volume element (RVE) in ABAQUS® to generate cubes several tens of microns in dimension and subjected to various prescribed deformation modes to generate the effective elastic tensor of the material. The RVE-calculated elastic properties such as moduli and Poisson's ratio are validated through an asymptotic expansion homogenization (AEH) and compared with rule of mixtures. Both periodic (PBC) and kinematic boundary conditions (KBC) are investigated to determine if the elastic properties are invariant due to boundary conditions. In addition, the method of “Windowing” was used to assess the randomness of the constituents and to validate how the isotropic elastic properties were determined. The average elastic properties obtained from the displacement based FEA of various locally anisotropic microsize cubes extracted from an RVE of size 100 × 100 × 100 μm showed that the overall RVE response was fully isotropic. The effects of domain size, degree of hydration (DOH), kinematic and periodic boundary conditions, domain sampling techniques, local anisotropy, particle size distribution (PSD), and random microstructure on elastic properties are studied.

Research paper thumbnail of Study of forming limit diagram (FLD) prediction of anisotropic sheet metals using Gurson model in M-K method

International Journal of Material Forming, 2021

Research paper thumbnail of Transient and thermal contact analysis for the elastic behavior of functionally graded brake disks due to mechanical and thermal loads

Materials and Design, 2010

In this paper, the transient and contact analysis of functionally graded (FG) brake disk is prese... more In this paper, the transient and contact analysis of functionally graded (FG) brake disk is presented. The analysis was carried out using ANSYS parametric design language (APDL). The FG brake disk is made of metal-ceramic material. The material properties vary in radial direction with the values from full-metal at the inner radius to that of full-ceramic at the outer radius. In the analysis, FG brake disk is in contact with one pure pad disk and coulomb contact friction is considered as heat source. The non-dimensional results are obtained for specific value of grading index (n = 1) by considering different material property divisions of 25, 50, 100 and 200. The results presented are for the pressure distribution, total stress, pad penetration, friction stress, heat flux and temperature during contact, for different values of contact stiffness factor, Fkn, which depends on the property gradation of FG brake disk with 200 material property divisions. The results show that the contact pressure and contact total stress increase with increasing values of Fkn, and hence it can be concluded that gradation of the metal-ceramic has significant effect in the thermomechanical response of FG brake disks.

Research paper thumbnail of Elastic Contact Analysis of Functionally Graded Brake Disks Subjected to Thermal and Mechanical Loads

International Journal for Computational Methods in Engineering Science and Mechanics, 2013

In this paper, finite element contact analysis of a functionally graded (FG) brake disk in contac... more In this paper, finite element contact analysis of a functionally graded (FG) brake disk in contact with a pad, subjected to rotation, contact pressure, and frictional heat, is presented. The material properties vary through the thickness according to a power-law characterized by a grading index, n. The contact surfaces are full-ceramic with full-metal free surface. The effects of n on the displacement, contact status, strain and stress are investigated. From the analysis, thermo-elastic and contact results are extremely dependent on n. Hence, n is an important criteria for the design of FG brake disks for automotive and aircraft applications.

Research paper thumbnail of The effect of superimposed hydrostatic pressure on shear decohesion in round bar tensile specimens

International Journal of Fracture, 2022

Research paper thumbnail of Finite element analysis of elastic–plastic and fracture behavior in functionally graded materials (FGMs)

The effect of material property variation on ductility and fracture strain in functionally graded... more The effect of material property variation on ductility and fracture strain in functionally graded materials (FGMs) is investigated using the finite element method (FEM) and the Gurson–Tvergaard–Needleman (GTN) model, which is strain-controlled for void nucleating. The material properties of FGMs in the tensile tests are assumed to be represented by a power-law distribution in the thickness direction. A gradation index (n) assigns the material property distribution. The lower and upper surfaces are pure hard (n = ∞) and pure soft (n = 0) materials, respectively, in the simulations. The ductility and fracture strain changes with varying gradation index. The development of stress triaxiality slows down in FGMs, and the total void volume fraction is reduced. The analysis is performed for five values of n, and the results are discussed numerically. The aim of this study is to help the researchers for better design and fabrication of FGMs. The necking strain in FGMs is calculated and it i...

Research paper thumbnail of Study of Influence of Width to Thickness Ratio in Sheet Metals on Bendability under Ambient and Superimposed Hydrostatic Pressure

Applied Mechanics

The effect of the width to thickness ratio on the bendability of sheet metal is investigated usin... more The effect of the width to thickness ratio on the bendability of sheet metal is investigated using the finite element method (FEM) employing the Gurson–Tvergaard–Needleman (GTN) model. Strain path changes in the sheet with change in the width/thickness ratio. It is shown that bendability and fracture strain increase significantly by decrease in the width/thickness ratio. The stress state is almost uniaxial when the stress ratio (α) is close to zero for narrow sheets. Stress ratio is nothing but the major stress to minor stress ratio. This delays the growth and coalescence of micro-voids as the volumetric strain and stress triaxiality (pressure/effective stress) decrease. On the other hand, ductility decreases with increase in α for wider sheets. Fracture bending strain is calculated and, as expected, it increases with decrease in the width/thickness ratio. Furthermore, a brief study is performed to understand the effect of superimposed hydrostatic pressure on fracture strain for var...

Research paper thumbnail of Representative volume element based modeling of cementitious materials

The current work focuses on evaluation of the effective elastic properties of cementitious materi... more The current work focuses on evaluation of the effective elastic properties of cementitious materials through a voxel based finite element analysis (FEA) approach. Voxels are generated for a heterogeneous cementitious material (type-I cement) consisting of typical volume fractions of various constituent phases from digital microstructures. The microstructure is modeled as a microscale representative volume element (RVE) in ABAQUS® to generate cubes several tens of microns in dimension and subjected to various prescribed deformation modes to generate the effective elastic tensor of the material. The RVE-calculated elastic properties such as moduli and Poisson's ratio are validated through an asymptotic expansion homogenization (AEH) and compared with rule of mixtures. Both periodic (PBC) and kinematic boundary conditions (KBC) are investigated to determine if the elastic properties are invariant due to boundary conditions. In addition, the method of “Windowing” was used to assess the randomness of the constituents and to validate how the isotropic elastic properties were determined. The average elastic properties obtained from the displacement based FEA of various locally anisotropic microsize cubes extracted from an RVE of size 100 × 100 × 100 μm showed that the overall RVE response was fully isotropic. The effects of domain size, degree of hydration (DOH), kinematic and periodic boundary conditions, domain sampling techniques, local anisotropy, particle size distribution (PSD), and random microstructure on elastic properties are studied.