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Main and interaction effects of manufacturing variables on microstructure and fracture of solder-copper connections
, Article Engineering Failure Analysis ; Volume 139 , 2022 ; 13506307 (ISSN) ; Nourani, A ; Hossein Farrahi, G ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Finding the optimized set of manufacturing parameters to produce strong solder-copper connections requires investigating the main and interaction effects of processing variables on the joint strength and microstructure. In this study, solder joint specimens were prepared at different levels of cooling rate, time above liquidus (TAL), and soldering temperature. Mode I fracture experiments were designed and performed at a strain rate of 0.5 s−1. The fracture load remained constant from the cooling rate of 0.1 to 1.4 °C/s and then decreased by almost 34% with further increase in the cooling rate to 34 °C/s. Increasing TAL from 60 to 120 s reduced the fracture load by almost 27%, while it was...
Deformation and creep characteristics of AA7075-T76 at elevated temperatures
, Article Journal of Materials Engineering and Performance ; Volume 31, Issue 9 , 2022 , Pages 7586-7595 ; 10599495 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
Springer
2022
Abstract
In this work, deformation behavior as well as creep and cavitation of AA7075-T76 were studied. The as-received plate was first stabilized utilizing solution treatment followed by two-stage artificial aging at 120 and 180 °C. Then, tensile tests were carried out on the aged-alloy in the temperature range between 120 and 250 °C under strain rates of 0.0005 and 0.005 s−1. Furthermore, stress-controlled creep tests were performed at temperatures varying between 120 and 210 °C at stresses ranging from 130 to 250 MPa. Microstructural evolution was then conducted to assess the microstructural changes and growth of cavities during creep employing optical metallography and scanning electron...
Effects of molecular structure on thermal, rheological and mechanical properties of drip irrigation PE tapes
, Article Journal of Polymer Research ; Volume 29, Issue 10 , 2022 ; 10229760 (ISSN) ; Pircheraghi, G ; Houshmandmoayed, S ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Considering the microstructure-processing-properties relationship, the attempt was made to distinguish the main structural features of drip irrigation tape grades. In this regards, two different commercial polyethylene grades using for irrigation tape application (DB and MD samples) with various microstructural features were fully characterized by means of thermal, rheological and mechanical measurements and microscopic observations. A set of DSC techniques revealed that DB sample has faster crystallization kinetic probably due to its high crystallizable segments in chains and broad molecular weight distribution. It was found, the type of co-monomer used in DB sample is 1-hexene and in MD...
Development of consistent fish-bone simplified model with energy-based approach for efficient seismic evaluation of irregular steel moment resisting frames
, Article Soil Dynamics and Earthquake Engineering ; Volume 161 , 2022 ; 02677261 (ISSN) ; Ahmadie Amiri, H ; Esmailpur Estekanchi, H ; Kheirkhah Gildeh, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This study aims to develop the Consistent Fish-Bone (CFB) simplified model for efficient estimation of Engineering Demand Parameters (EDPs) in irregular steel Moment Resisting Frames (steel-MRFs). To achieve this goal, some modifications based on the energy consistent approach have been applied to the Improved Fish-Bone (IFB) simplified model previously presented for reinforced concrete MRFs. These modifications include: 1) adding truss elements to the IFB model to consider the effect of flexural deformations and determining their areas by balancing the overturning moment and the strain energy due to the axial deformation of columns in the original steel-MRF with the overturning moment and...
Obtaining strain-rate dependent traction-separation law parameters of epoxy adhesive joints and predicting fracture for dissimilar bonding adherends
, Article International Journal of Adhesion and Adhesives ; Volume 118 , 2022 ; 01437496 (ISSN) ; Nourani, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This study investigated the mode I fracture behavior of double cantilever beam (DCB) epoxy adhesive joints with similar adherends on the both sides (i.e., aluminum-aluminum or copper-copper) at different strain rates; i.e., quasi-static (∼10−3 s−1), low (∼7 s−1) and intermediate (∼14 s−1) rates. The fracture energy of the DCB joint in Al-adhesive-Al specimens decreased (i.e., by ∼62%, p = 0.0013) with an increase in the applied strain rate from quasi-static to low values, while it remained almost unchanged with further increase of stain rate to intermediate range (p > 0.05). For Cu-adhesive-Cu cases, however, the fracture energy was found to be almost insensitive to the applied strain rate...
Large deformation of shape-memory polymer-based lattice metamaterials
, Article International Journal of Mechanical Sciences ; Volume 232 , 2022 ; 00207403 (ISSN) ; Jebellat, E ; Roudbarian, N ; Mohammadi, K ; Movahhedy, M. R ; Asle Zaeem, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Through advanced computational analysis, this work demonstrates that metamaterial structures when made by shape-memory polymers (SMPs) can provide unique intelligent mechanical behavior. For the first time, geometrical effects, pertaining to low and ultra-low densities, on the thermomechanical behavior of SMP-based octet-truss lattice meta-structures are studied in this work. A reliable constitutive thermo-visco-hyperelastic model is applied to analyze the shape-memory behavior of several designed octet-truss lattices with ultra-low and low relative densities, ranging from 0.04 to 0.23. Different compressive strain values are tested to determine the effect of pre-straining. It is concluded...
Friction stir welding of severely plastic deformed aluminum using (Al2O3+ graphite) hybrid powders: Grain structure stability and mechanical performance
, Article Journal of Materials Research and Technology ; Volume 21 , 2022 , Pages 961-980 ; 22387854 (ISSN) ; Movahedi, M ; Kazeminezhad, M ; Sharif University of Technology
Elsevier Editora Ltda
2022
Abstract
Welding of severely plastic deformed aluminum sheets, with high stored strain energy, faces a serious concern, which is decrease in strength of weld and heat-affected zone (HAZ) due to instability in microstructure and related grain growth. In this work, two-passes constrained groove pressed (CGPed) Al-1050 sheets were welded via friction stir welding (FSW), without and with addition of a hybrid powder including 50 vol.% α-Al2O3 nanoparticles+50 vol.% graphite micrometric powders (∼1 vol.% of hybrid powders in stir zone). Al2O3 nanoparticles may result in grain refinement in stir zone by grain boundary pinning. Lubricating nature of graphite may reduce welding heat input resulting in lower...
Forced and free vibrational analysis of viscoelastic nanotubes conveying fluid subjected to moving load in hygro-thermo-magnetic environments with surface effects
, Article Archives of Civil and Mechanical Engineering ; Volume 22, Issue 4 , 2022 ; 16449665 (ISSN) ; Alibeigloo, A ; Borjalilou, V ; Koochakianfard, O ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Forced and free vibrational analyses of viscoelastic nanotubes containing fluid under a moving load in complex environments incorporating surface effects are conducted based on the nonlocal strain gradient theory and the Rayleigh beam model. To model the internal nanoflow, the slip boundary condition is employed. Adopting the Galerkin discretization approach, the reduced-order dynamic model of the system is acquired. Analytical and numerical methods are exploited to determine the dynamic response of the system. The impacts of geometry, scale parameter ratio, Knudsen number, fluid velocity, rotary inertia parameter, viscoelastic parameter, surface residual stress, surface elastic modulus, and...
The effect of bainite volume fraction on wear behavior of aisi 4340 ferrite–bainite dual-phase steel
, Article Journal of Materials Engineering and Performance ; Volume 31, Issue 11 , 2022 , Pages 8687-8698 ; 10599495 (ISSN) ; Ekrami, A ; Sharif University of Technology
Springer
2022
Abstract
The tribological behaviors of an AISI 4340 ferritic-bainitic dual-phase steel with different bainite (VB) content were investigated. The effects of VB on wear resistance and the corresponding wear mechanisms were investigated using a pin-on-disk wear testing machine, at normal loads of 10 and 50 N, at a constant sliding velocity. The tensile and hardness tests showed that the yield strength, ultimate tensile strength, and hardness increased with increasing the VB. The wear test results at the 10 N normal load showed a direct correlation between the tensile and tribological behavior of the samples. Nevertheless, at the normal load of 50 N, unexpected behavior was observed due to the carbon...
Evaluation of sample scale effect on geomechanical tests
, Article Petroleum Research ; Volume 7, Issue 4 , 2022 , Pages 527-535 ; 20962495 (ISSN) ; Shad, S ; Zivar, D ; Sharif University of Technology
KeAi Publishing Communications Ltd
2022
Abstract
The size of the rock specimen affects the stress concentrates in the vicinity of the top/bottom of the rock specimen during the evaluation of the geomechanical parameters in the laboratory, which causes unreliable results. However, the appropriate size for geomechanical evaluation is not well understood yet because of limitations in the sampling and analysis. In this study, a series of numerical simulations using a finite element package was conducted to investigate the effect of sample aspect ratio, fluid saturation, and porosity, on the mechanical behavior of the rock under elastic and poroelastic conditions. In addition, two concepts, stress/strain homogeneity index (SHI) and...
A new look at tensile yielding in isotactic polypropylene: role of strain rate and thermal softening
, Article Polymer Bulletin ; Volume 79, Issue 12 , 2022 , Pages 11157-11176 ; 01700839 (ISSN) ; Bagheri, R ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Polypropylene (PP) is a semi-crystalline polymer with a very wide range of industrial applications. This is why its mechanical properties, including yielding, have been the subject of numerous studies. The current study has examined the influence of strain rate and thermal softening on yield stress and post yielding behavior of an isotactic PP. A two-process Ree and Eyring model and the heat equation in adiabatic deformation were coupled with a physical parameter described as the temperature sensitivity of the flow stress at yielding, to simulate the effect of gradual temperature rise in adiabatic heating on yielding behavior. Along with that, tensile bars were subjected to tests at...
Modified Green–Lindsay analysis of an electro-magneto elastic functionally graded medium with temperature dependency of materials
, Article Mechanics of Time-Dependent Materials ; Volume 26, Issue 4 , 2022 , Pages 871-890 ; 13852000 (ISSN) ; Razavinasab, S. M ; Sharif University of Technology
Institute for Ionics
2022
Abstract
This article presents a modified Green–Lindsay (MG-L) thermoelasticity model considering temperature and strain rate. Previously, this model has been developed based on the Green–Lindsay theory of thermoelasticity using strain and temperature rate dependent thermoelastic equations. This study analyzes stress and thermal wave propagation of a functionally graded medium exposed to an electromagnetic field and a thermal shock. All magnetic, elastic, and thermal features of the medium are considered to vary in the longitudinal direction. Additionally, the properties of the material are dependent on the temperature in the form of a cubic function. Using the large displacement formulation and the...
A comprehensive mathematical simulation of the composite size-dependent rotary 3D microsystem via two-dimensional generalized differential quadrature method
, Article Engineering with Computers ; Volume 38 , 2022 , Pages 4181-4196 ; 01770667 (ISSN) ; Zhao, Y ; Pishbin, M ; Habibi, M ; Bashir, M. O ; Issakhov, A ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
In this study, frequency simulation and critical angular velocity of a size-dependent laminated rotary microsystem using modified couple stress theory (MCST) as the higher-order elasticity model is undertaken. The centrifugal and Coriolis impacts due to the spinning are taken into account. The size-dependent thick annular microsystem's computational formulation, non-classical governing equations, and corresponding boundary conditions are obtained by using the higher-order stress tensors and symmetric rotation gradient to the strain energy. By using a single material length scale factor, the most recent non-classical approach captures the size-dependency in the annular laminated microsystem....
Phase field theory for fracture at large strains including surface stresses
, Article International Journal of Engineering Science ; Volume 178 , 2022 ; 00207225 (ISSN) ; Farrahi, G. H ; Levitas, V. I ; Javanbakht, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Phase field theory for fracture is developed at large strains with an emphasis on a correct introduction of surface stresses at nanoscale. This is achieved by multiplying the cohesion and gradient energies by the local ratio of the crack surface areas in the deformed and undeformed configurations and with the gradient energy in terms of the gradient of the order parameter in the reference configuration. This results in an expression for the surface stresses which is consistent with the sharp surface approach. Namely, the structural part of the Cauchy surface stress represents an isotropic biaxial tension, with the magnitude of a force per unit length equal to the surface energy. The surface...
Mechanical properties and γ/γ' interfacial misfit network evolution: A study towards the creep behavior of Ni-based single crystal superalloys
, Article Mechanics of Materials ; Volume 171 , 2022 ; 01676636 (ISSN) ; Youzi, M ; Tolooei Eshlaghi, G ; Sharif University of Technology
Elsevier B.V
2022
Abstract
The aim of this study is to investigate the role of the temperature, stress, and rhenium (Re) on the γ/γ' interfacial misfit dislocation network and mechanical response of Ni-based single crystal superalloys. After aging at elevated temperatures, mismatch between the two phases results in an interfacial dislocation network to relieve the coherency stress. Molecular dynamics (MD) simulations have been performed to study the properties of the (100), (110), and (111) phase interface crystallographic directions. Increasing temperature disperses the atomic potential energy at the interface diminishing the strength and stability of the networks. In the case of loading, when a constant strain rate...
A modified two-surface plasticity model for saturated and unsaturated soils
, Article Indian Geotechnical Journal ; Volume 52, Issue 4 , 2022 , Pages 865-876 ; 09719555 (ISSN) ; Hajitaheriha, M. M ; Hasani Motlagh, A ; Sadeghi, H ; Sharif University of Technology
Springer
2022
Abstract
A modified two-surface critical state plasticity model for saturated and unsaturated soil is presented in this study. The key modification in new model is inclusion of an alternative yield surface used to simulate the behavior of unsaturated soils in addition to corresponding saturated conditions. Moreover, a numerical technique is used to obtain an incremental stress–strain response from loading curves. Modification is applied continuously in each incremental step to return the final stress states and hardening parameters to the yield surface. Results revealed that the adopted modeling approach can predict two independent sets of laboratory unsaturated experiments under various conditions...
The effect of carbon on the restoration phenomena during hot deformation of carbon steels
, Article International Journal of Materials Research ; Volume 94, Issue 8 , 2022 , Pages 916-921 ; 18625282 (ISSN) ; Karimi Taheri, A ; Zebarjad, S. M ; Sharif University of Technology
Walter de Gruyter GmbH
2022
Abstract
A study has been made to determine the influence of the carbon content on the kinetics of dynamic and static recrystallization during and after hot deformation of carbon steels. For this purpose, single- and double-hit hot compression experiments at various strain rates and temperatures together with the Avrami-type kinetics equation and Bergstrom approach have been utilized to investigate recrystallization behavior. The results show that the apparent activation energy of hot deformation decreases with increasing carbon content and this phenomenon results in a faster dynamic recrystallization at high temperatures and/or low strain rates. Also, increasing carbon content leads to a higher rate...
Coupled continuum damage mechanics and crystal plasticity model and its application in damage evolution in polycrystalline aggregates
, Article Engineering with Computers ; Volume 38 , 2022 , Pages 2121-2135 ; 01770667 (ISSN) ; Assempour, A ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
In the present study, damage initiation and growth in a polycrystalline aggregate are investigated. In this regard, an anisotropic continuum damage mechanics coupled with rate-dependent crystal plasticity theory is employed. Using a thermodynamically consistent procedure, a finite deformation formulation is derived. For this purpose, the damage tensor is incorporated in the crystal plasticity formulation for a cubic single crystal. The damage evolution is considered to be dependent on the history of damage, equivalent plastic strain, stress triaxiality, and Lode parameters. This material model is implemented in the commercial finite-element code Abaqus/Standard by developing a user material...
A compatible mixed finite element method for large deformation analysis of two-dimensional compressible solids in spatial configuration
, Article International Journal for Numerical Methods in Engineering ; Volume 123, Issue 15 , 2022 , Pages 3530-3566 ; 00295981 (ISSN) ; Sharif University of Technology
John Wiley and Sons Ltd
2022
Abstract
In this article, a new mixed finite element formulation is presented for the analysis of two-dimensional compressible solids in finite strain regime. A three-field Hu–Washizu functional, with displacement, displacement gradient and stress tensor considered as independent fields, is utilized to develop the formulation in spatial configuration. Certain constraints are imposed on displacement gradient and stress tensor so that they satisfy the required continuity conditions across the boundary of elements. From theoretical standpoint, simplex elements are best suited for the application of continuity constraints. The techniques that are proposed to implement the constraints facilitate their...
Atomistic study of the effect of crystallographic orientation on the twinning and detwinning behavior of NiTi shape memory alloys
, Article Computational Materials Science ; Volume 203 , 2022 ; 09270256 (ISSN) ; Izadifar, M ; Dolado, J. S ; Ramazani, A ; Sadrnezhaad, S. K ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Understanding the effect of crystallographic orientation on the twinnin/detwinning mechanisms in NiTi shape memory alloys at an atomistic scale can help to control and tune the mechanical properties and failure behavior of such materials. In this work, we employed classical molecular dynamics (MD) and density functional theory (DFT) computational methods to better understand how twinning and detwinning occurs through a combination of slip, twin, and shuffle on 〈0 1 0〉, 〈1 1 0〉, and 〈1 1 1〉 crystallographic orientations under uniaxial tensile test. Elastic constants including Young's Modulus (E), Bulk modulus (B), Poisson's ratio (ν), and Shear Modulus (G) are obtained and computed for...