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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...
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...
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...
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...
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...
Early post-operative performance of an anatomically designed hybrid thread interference screw for ACL reconstruction: A comparative study
, Article Journal of Biomechanics ; Volume 135 , 2022 ; 00219290 (ISSN) ; Chizari, M ; Javad Mortazavi, S. M ; Rouhi, G ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Although the anterior cruciate ligament (ACL) reconstruction using interference screw is a well-accepted surgical procedure, patients still suffer graft failure in the initial rehabilitation phase. Graft fixation stability of a newly designed anatomical hybrid thread tapered interference screw (AHTTIS) was compared with a conventional standard one (CSIS) by conducting in-vitro mechanical tests. According to the CSIS manufacturer's instruction, eight tapered bone tunnels, matching AHTTIS geometry, and eight straight cylindrical tunnels were drilled in artificial bone blocks. Bovine tendon grafts were fixed using AHTTIS and CSIS in their corresponding bone tunnels. Each graft was subjected to...
Modeling the dual-fuel combustion of porous lycopodium particles and diesel using an analytical simulation framework
, Article Journal of Analytical and Applied Pyrolysis ; Volume 163 , 2022 ; 01652370 (ISSN) ; Akbari, S ; Faghiri, S ; Sadeghi, S ; Xu, F ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In this paper, a comprehensive analytical study is performed to assess the lycopodium-diesel dual-fuel combustion system in counter-flow premixed configuration. The system is modeled as multiple zones that are coupled together via proper boundary and jump conditions on interfaces. According to the respective reaction and transport phenomena in these zones, conservation equations of mass and energy are derived, non-dimensionalized, and solved by Matlab and Mathematica in an analytical way. The porosity of lycopodium particles and the thermal radiation from the reaction zone and the post-flame zones into the preheating zone are considered, in order to improve the realism and accuracy of the...
Assessment of optimal reaction progress variable characteristics for partially premixed flames
, Article Combustion Theory and Modelling ; Volume 26, Issue 5 , 2022 , Pages 797-830 ; 13647830 (ISSN) ; Ommi, F ; Farshchi, M ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
The reaction progress variable is a crucial concept in the advanced flamelet combustion models. As a controlling variable, a well-defined progress variable must consider the essential features of the combustion process. It is usually a heuristically defined linear combination of some major chemical species mass fractions. However, such a simple definition could lead to inaccurate results for the fuel-rich reactive mixtures or complicated fuels, due to the vast number of chemical species in the combustion process. In this paper, a new method for generating a reaction progress variable is proposed through solving a constrained optimisation problem. The proposed method uses a genetic algorithm...
Geometry influence on fracture behavior of lap-shear solder joints
, Article IEEE Transactions on Components, Packaging and Manufacturing Technology ; Volume 12, Issue 1 , 2022 , Pages 80-88 ; 21563950 (ISSN) ; Nourani, A ; Honarvar, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Single lap-shear (SLS) specimens of 63Sn37Pb solder joints were prepared with three different adherend thicknesses at three varying joint lengths. The fracture force was measured at a shear strain rate of 0.01 s-1 for different geometries. The elastic-plastic fracture mechanics (EPFM) theory was used to find the energy dissipated in each case using a finite element model (FEM), and the fracture energy was obtained by cohesive zone modeling (CZM). Both 2-D and 3-D models were used to explain the variations in fracture energy by the level of constraint on the joint. Also, the plastic zone area and stress distribution along the solder layer were calculated at the moment of fracture. A phase...
Effect of building direction on high strain-rate compressive behavior of heat-treated LPBF-maraging steels using Split Hopkinson pressure bar apparatus
, Article Materials Science and Engineering A ; Volume 835 , 2022 ; 09215093 (ISSN) ; Pirgazi, H ; Sanjari, M ; Seraj, P ; Odeshi, A ; Kestens, L. A. I ; Mohammadi, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Rod-shaped samples of maraging steel were additively fabricated in vertical and horizontal directions using laser powder bed fusion technique. The samples were first aged at 490 °C for 6 h and then subjected to dynamic compressive tests using Split Hopkinson Pressure Bar apparatus. The dynamic compression tests were conducted on vertical samples at strain rates of 190, 460, 810, 1100, 1300 s−1. However, the high strain rate tests were performed at strain rates of 120, 615, 745, 890, 2200 s−1 on horizontal samples. After applying the compressive impact loads on the samples, it was found that although horizontally built samples exhibit higher dynamic strength, vertically built samples show...
A novel procedure for micromechanical characterization of white matter constituents at various strain rates
, Article Scientia Iranica ; Volume 27, Issue 2 , 2021 , Pages 784-794 ; 10263098 (ISSN) ; Farahmand, F ; Ahmadian, M. T ; Sharif University of Technology
Sharif University of Technology
2021
Abstract
Optimal hyperplastic coeficients of the micromechanical constituents of the human brain stem were investigated. An evolutionary optimization algorithm was combined with a Finite Element (FE) model of a Representative Volume Element (RVE) to nd the optimal material properties of axon and Extra Cellular Matrix (ECM). The tension and compression test results of a previously published experiment were used for optimizing the material coeficients, and the shear experiment was used for the validation of the resulting constitutive model. The optimization algorithm was used to search for optimal shear moduli and ber sti ness of axon and ECM by tting the average stress in the axonal direction with the...
Temperature dependence of serrated flow, strain-rate sensitivity and activation volume in a Ti-based bulk metallic glass
, Article Journal of Non-Crystalline Solids ; Volume 553 , 2021 ; 00223093 (ISSN) ; Tavakoli, R ; Aashuri, H ; Sharif University of Technology
Elsevier B. V
2021
Abstract
In this study, the influence of temperature on serrated flow behavior, strain rate sensitivity (SRS) and effective activation volume in a Ti-based bulk metallic glass (BMG) bent at different strain rates has been investigated. Results reveal that the fundamental origin of shear deformation is related to the time-dependent structural relaxations, which occur during deformation at special temperatures and strain rates. Furthermore, the localized structural relaxation processes at intermediate temperatures cause an inelastic shuffling within cages and mitigate the activation of STZs. The main reason of negative SRS at intermediate temperatures is due to the insufficient time for structural...
Atomistic simulation of creep deformation mechanisms in nickel-based single crystal superalloys
, Article Materials Science and Engineering A ; Volume 809 , 2021 ; 09215093 (ISSN) ; Tolooei Eshlaghi, G ; Shahoveisi, S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this paper, the creep deformation mechanisms are investigated in nickel-based single crystal superalloys. Two-dimensional molecular dynamics (MD) simulations are conducted to model various temperatures, stress conditions, and phase interface crystal orientations. Ni-based single-crystal superalloys are of great importance in the aircraft industry due to their excellent high temperature creep resistance. This characteristic mainly originates from two features considered in their structure; firstly, their two-phase micro-structure comprising gamma γ and gamma prime γ′, and secondly the nature of this superalloy itself, which is a single-crystal. MD is a powerful tool to gain insight into...
Influence of joint arrangement on the fracture behavior of lead-free solder joints
, Article Journal of Electronic Materials ; Volume 50, Issue 4 , 2021 , Pages 2117-2128 ; 03615235 (ISSN) ; Nourani, A ; Honarmand, M ; Assempour, A ; Sharif University of Technology
Springer
2021
Abstract
The capability to standardize the fracture strength of solder joints is an effective tool to investigate the reliability of electronic devices. To achieve this purpose, in this research, the influences of joint arrangement (loading arm and load sharing) on the level of constraint imposed on joint deformation, fracture energy, and generally, fracture behavior of solder joints were investigated. Fracture behavior of solder joints using double-cantilever-beam (DCB) specimens as a function of loading arm and load sharing (i.e., the distance between two solder joints) was studied under mode I loading conditions at a strain rate of 0.03 s−1. By increasing the loading arm, the fracture force, Fci,...
Modified Green–Lindsay analysis of an electro-magneto elastic functionally graded medium with temperature dependency of materials
, Article Mechanics of Time-Dependent Materials ; 2021 ; 13852000 (ISSN) ; Razavinasab, S. M ; Sharif University of Technology
Springer Science and Business Media B.V
2021
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...
Analysis and modification of a common energy harvesting system using magnetic shape memory alloys
, Article Journal of Intelligent Material Systems and Structures ; Volume 32, Issue 5 , 2021 , Pages 568-583 ; 1045389X (ISSN) ; Mehrabi, M ; Hoviattalab, M ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
In this paper, a common energy harvester is investigated which uses a specimen of magnetic shape memory alloy (MSMA). The aim of this study is to improve system performance and to evaluate the magneto-mechanical loading on the MSMA material. Since demagnetization effect is not included in the employed original MSMA model, a method to incorporate this effect is proposed which has a good performance for the specific magneto-mechanical loading of this problem. In order to decrease the need for bias magnetic field and increase system efficiency, a new return mechanism for the MSMA specimen is proposed. The results indicate that the maximum harvested power from the improved system is obtained at...
Effects of Brownian motions and thermophoresis diffusions on the hematocrit and LDL concentration/diameter of pulsatile non-Newtonian blood in abdominal aortic aneurysm
, Article Journal of Non-Newtonian Fluid Mechanics ; Volume 294 , 2021 ; 03770257 (ISSN) ; Esfahani, A. N ; Golab, E ; Golestanian, O ; Ashouri, N ; Sajadi, S. M ; Ghaemi, F ; Baleanu, D ; Karimipour, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
LDL concentration is believed to be responsible for plaque formation that leads to atherosclerotic cardiovascular disease. We conducted this study to investigate the effects of hematocrits and LDL diameters on LDL concentration on the wall of an abdominal aortic aneurysm (AAA). The blood flow was considered to be a pulsatile and non-Newtonian flow whose viscosity was a function of hematocrits and strain rate. Lumen, Brownian, and thermophoresis diffusions were analyzed in LDL concentration. The results demonstrated that adding thermophoresis diffusion increases LDL concentration. Moreover, among three types of LDLs, including small LDLs, intermediate LDLs, and large LDLs, small LDLs were the...
Time-varying structural reliability assessment method: Application to fiber reinforced composites under repeated impact loading
, Article Composite Structures ; Volume 261 , 2021 ; 02638223 (ISSN) ; Pourtakdoust, S. H ; Crawford, B. J ; Seethaler, R ; Milani, A. S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Reliability evaluations play a significant role in engineering applications to ensure the serviceability and safety of advanced structures such as those made of composites. Here, a dynamic reliability evaluation analysis based on the probability density evolution Method (PDEM) has been adapted to assess the reliability of composite structures under uncertainties within the material properties and the external loadings. A Back-Propagation Neural Network approach is employed to identify the system's nonlinear structural response, which is often the case under large deformations. To exemplify, a split Hopkinson pressure bar system was employed to mimic the mechanical behavior of a...