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stress-distribution
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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...
The influence of welding polarity on mechanical properties, microstructure and residual stresses of gas tungsten arc welded AA5052
, Article International Journal of Advanced Manufacturing Technology ; Volume 105, Issue 7-8 , 2019 , Pages 3397-3409 ; 02683768 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
Springer
2019
Abstract
The effect of welding current and polarity, i.e. AC and DCEN, on imposed thermal cycles, mechanical properties, microstructural events and residual stresses was investigated in GTA welding of AA5052. A three-dimensional thermo-mechanical model was utilized to evaluate thermal responses and residual stresses distribution in the weldments. Tensile testing and hardness measurements were also conducted to study the effect of welding polarity on the mechanical properties of components. Microstructural observations utilizing optical microscopy were carried out to assess the microstructural evolutions. The results show that wide varieties of microstructures are produced in DCEN sample from cells at...
Dielectrophoretic interaction of two particles in a uniform electric field
, Article Microsystem Technologies ; Volume 25, Issue 7 , 2019 , Pages 2699-2711 ; 09467076 (ISSN) ; Moghimi Zand, M ; Dastani, K ; Sharif University of Technology
Springer Verlag
2019
Abstract
The local electric field distorsion induced by a dielectric particle leads to particle–particle interactions and assembly which is very interesting for their useful applications on microfluidic devices. Particles behavior becomes more complicated if several particles interact at the same time. This paper presents a comprehensive numerical analysis of the assembly and particle–particle interactions for two similar and dissimilar dielectric particles immersed in a dielectric fluid using the immersed interface method based on two-dimensional direct-current dielectrophoresis. The immersed interface method is a finite-difference (or finite element) based numerical method which its key advantage...
A comprehensive experimental and numerical study on redistribution of residual stresses by shot peening
, Article Materials and Design ; Volume 90 , 2016 , Pages 478-487 ; 02641275 (ISSN) ; Ghasemi, A ; Farrahi, G. H ; Sherafatnia, K ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Shot peening is one of the most effective surface strengthening treatment technologies in which compressive residual stresses are induced beneath the specimen surface. Effects of various factors on the distribution of residual stress profile induced by shot peening have been investigated by many researchers. However, initial residual stresses are one of the important factors which affect the shot peening residual stress.This study is aimed to present comprehensive numerical and experimental study on the effect of initial residual stresses on the shot peened specimen. Initial residual stresses were induced using a four-point bending rig and grinding. Incremental center hole drilling (ICHD)...
Residual stress analyses of re-autofrettaged thick-walled tubes
, Article International Journal of Pressure Vessels and Piping ; Volume 98 , 2012 , Pages 57-64 ; 03080161 (ISSN) ; Voyiadjis, G. Z ; Hoseini, S. H ; Hosseinian, E ; Sharif University of Technology
Elsevier
2012
Abstract
In this paper the effect of the re-autofrettage process on the residual stress distribution at the wall of a thick-walled tube is considered. For accurate material behavior modeling, it is assumed that the yield surface is a function of all the stress invariants. Also for estimating the behavior of the material under loading-unloading process, a modified Chaboche's hardening model is applied. For evaluation of this unloading behavior model a series of loading-unloading tests are conducted on specimens that are made of the high strength steel, DIN1.6959. In addition the finite element simulations are implemented to simulate the re-autofrettage process and to estimate the residual stresses....
Thermo-mechanical analysis of rotating disks with non-uniform thickness and material properties
, Article International Journal of Pressure Vessels and Piping ; Volume 98 , October , 2012 , Pages 95-101 ; 03080161 (ISSN) ; Hojjati, M. H ; Mahdavi, E ; Alashti, R. A ; Farrahi, G ; Sharif University of Technology
Elsevier
2012
Abstract
Theoretical and numerical analyses of rotating disks with non-uniform thickness and material properties subjected to thermo-mechanical loadings have been carried out by variable material properties (VMP), Runge-Kutta's (RK) and finite element (FE) methods. The material is assumed to be elastic-linear hardening. A power form function is used to describe the temperature gradient with the higher temperature at outer surface. Von-Mises theory has been used as failure criterion. The effects of geometry, material and thermal loading parameters as well as boundary conditions on radial, hoop and equivalent stress distributions which have not been studied in much detail in previous works have been...
The sliding frictional contact problem in two dimensional graded materials loaded by a flat stamp
, Article Advanced Materials Research, 7 January 2012 through 8 January 2012 ; Volume 463-464 , January , 2012 , Pages 336-342 ; 10226680 (ISSN) ; 9783037853634 (ISBN) ; Adibnazari, S ; Tashi, S ; Sharif University of Technology
2012
Abstract
In this article, the sliding frictional contact problem for a half-plane which is graded in two dimensions is studied. The effect of medium properties gradient and coefficient of friction in contact mechanics of two dimensional (2D) graded materials which is loaded by a flat stamp have been investigated by developing two Finite Element (FE) models, in macro and micro scales. Discretizing the graded half-plane by quadrants for whose material properties are specified at the centroids by Mori-Tanaka method in both directions has been used to model the 2D FGM in macro scale. In micro scale, the ideal solid quadrant particles which are spatially distributed in a homogeneous matrix used to model...
Numerical simulation of induction hardening of torsion bar
, Article Proceedings of the World Congress on Engineering 2011, WCE 2011, 6 July 2011 through 8 July 2011 ; Volume 3 , July , 2011 , Pages 2080-2083 ; 9789881925152 (ISBN) ; Farrahi, G. H ; Sharif University of Technology
2011
Abstract
In order to improve the fatigue performance of torsion bar, induction surface hardening is performed. The aim of the present study is to compare the experimental residual stress fields measured by X-ray diffraction with those predicted from finite element modeling of the whole induction surface hardening process. Temperature and residual stress distributions are affected by the component geometry, the material behavior and the induction treatment parameters. Based on the residual stress distribution and the fatigue loading, cracks can nucleate from the surface or below the hardened layer. Therefore, it is very important to determine the residual stress distribution and optimize the process,...
Surface and interface effects on torsion of eccentrically two-phase fcc circular nanorods: Determination of the surface/interface elastic properties via an atomistic approach
, Article Journal of Applied Mechanics, Transactions ASME ; Volume 78, Issue 1 , October , 2011 , Pages 0110111-01101111 ; 00218936 (ISSN) ; Shodja, H. M ; Sharif University of Technology
2011
Abstract
The effect of surface and interface elasticity in the analysis of the Saint-Venant torsion problem of an eccentrically two-phase fcc circular nanorod is considered; description of the behavior of such a small structure via usual classical theories cease to hold. In this work, the problem is formulated in the context of the surface/interface elasticity. For a rigorous solution of the proposed problem, conformal mapping with a Laurent series expansion are employed together. The numerical results well illustrate that the torsional rigidity and stress distribution corresponding to such nanosized structural elements are significantly affected by the size. In order to employ surface and interface...
Numerical study of the workpiece rotation effect on the strain and residual stress distribution in the cold radial forging process
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 4 , 2010 , Pages 785-792 ; 9780791849187 (ISBN) ; Movahhedy, M. R ; Sharif University of Technology
2010
Abstract
Radial forging is an open die forging process used for reducing the diameters of shafts, tubes, stepped shafts and axels, and for creating internal profiles in tubes. In this study, the effect of the workpiece rotation (the circumferential feed) on the strain and residual stress distribution in the inner surface of the tube in the cold radial forging process is investigated using nonlinear three dimensional finite element modeling. To verify the model, the predicted radial forging load is compared with the published experimental data which shows a good agreement. It is shown that for achieving a more favorable residual stress distribution in the workpiece inner surface, the rotation angle...
Anti-plane shear of an arbitrary oriented crack in a functionally graded strip bonded with two dissimilar half-planes
, Article Theoretical and Applied Fracture Mechanics ; Volume 54, Issue 3 , 2010 , Pages 180-188 ; 01678442 (ISSN) ; Kargarnovin, M. H ; Sharif University of Technology
2010
Abstract
An internal crack located within a functionally graded material (FGM) strip bonded with two dissimilar half-planes and under an anti-plane load is considered. The crack is oriented in an arbitrary direction. The material properties of strip are assumed to vary exponentially in the thickness direction and two half-planes are assumed to be isotropic. Governing differential equations are derived and to reduce the difficulty of the problem dealing with solution of a system of singular integral equations Fourier integral transform is employed. Semi closed form solution for the stress distribution in the medium is obtained and mode III stress intensity factor (SIF), at the crack tip is calculated...
An inverse method for reconstruction of the residual stress field in welded plates
, Article Journal of Pressure Vessel Technology, Transactions of the ASME ; Volume 132, Issue 6 , 2010 , Pages 0612051-0612059 ; 00949930 (ISSN) ; Faghidian, S. A ; Smith, D. J ; Sharif University of Technology
2010
Abstract
Welding process is widely used in manufacturing of many important engineering components. For such structures, the most important problem is the development of residual stresses and distortion due to welding. Welding tensile residual stresses have a detrimental effect and play an important role in an industrial environment. Crack initiation and propagation in static or fatigue loading, or in stress corrosion can be greatly accelerated by welding tensile stresses. Practically, however, it is often very difficult to characterize the residual stress state completely, while the knowledge of the complete residual stress distribution in structures is essential for assessing their safety and...
Investigating the effect of Casimir and van der Waals attractions on the electrostatic pull-in instability of nano-actuators
, Article Physica Scripta ; Volume 82, Issue 4 , 2010 ; 00318949 (ISSN) ; Koochi, A ; Kazemi, A. S ; Noghrehabadi, A ; Haddadpour, H ; Abadyan, M ; Sharif University of Technology
2010
Abstract
This paper investigates the effect of dispersion (van der Waals and Casimir) forces on the pull-in instability of cantilever nano-actuators by considering their range of application. Adomian decomposition is introduced to obtain an analytical solution of the distributed parameter model. Dispersion forces decrease the pull-in deflection and voltage of a nano-actuator. However, the fringing field increases the pull-in deflection while decreasing the pull-in voltage of the actuator. The minimum initial gap and the detachment length of the actuator that does not stick to the substrate due to van der Waals and Casimir attractions were determined. Furthermore, the proposed approach is capable of...
Buckling analysis of tapered composite beams using a higher order finite element formulation
, Article Journal of Reinforced Plastics and Composites ; Volume 29, Issue 17 , 2010 , Pages 2663-2683 ; 07316844 (ISSN) ; Ganesan, R ; Sharif University of Technology
2010
Abstract
Tapered composite beams are increasingly being used in various engineering applications such as helicopter yoke, robot arms, and turbine blades. In the present work, the buckling analysis of laminated tapered composite beams is conducted using a higher order finite element formulation. In tapered laminates, the material and geometric discontinuities at ply drop-off locations lead to significant discontinuities in stress distributions. Higher order formulation ensures the continuity of the stress distribution through the thickness of a laminate as well as across the element interfaces, which is very important for the analysis of tapered laminates. In addition, higher order finite element...
Transverse resistance of masonry infills
, Article ACI Structural Journal ; Volume 107, Issue 4 , 2010 , Pages 461-467 ; 08893241 (ISSN) ; Goudarzi, N ; Sharif University of Technology
2010
Abstract
In this paper, a confined infill panel previously experimented under out-of-plane loading is modeled and analyzed by the dynamic explicit method (DEM). This method is shown to have a good estimation of the experimental results, and is thus adopted to investigate the out-of-plane behavior of an infill model. Based on the analytical results, the stress distribution of an infill panel prior to and after cracking, and the effect of an arching mechanism on post-cracking behavior, is studied. A semi-empirical relationship is accordingly developed for predicting the transverse resistance of masonry infills due to one-way arching action, which accounts for the effects of the boundary frame...
Residual stress analysis of autofrettaged thick-walled spherical pressure vessel
, Article International Journal of Pressure Vessels and Piping ; Volume 87, Issue 7 , July , 2010 , Pages 396-401 ; 03080161 (ISSN) ; Farrahi, G. H ; Haghpanah Jahromi, B ; Hosseinian, E ; Sharif University of Technology
2010
Abstract
In this study, residual stress distributions in autofrettaged homogenous spherical pressure vessels subjected to different autofrettage pressures are evaluated. Results are obtained by developing an extension of variable material properties (VMP) method. The modification makes VMP method applicable for analyses of spherical vessels based on actual material behavior both in loading and unloading and considering variable Bauschinger effect. The residual stresses determined by employing finite element method are compared with VMP results and it is demonstrated that the using of simplified material models can cause significant error in estimation of hoop residual stress, especially near the...
Prediction of thermal stresses and temperature field in work rolls during hot strip rolling process
, Article Materials Science and Technology ; Volume 26, Issue 3 , 2010 , Pages 343-351 ; 02670836 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
2010
Abstract
In this work, a combined finite element analysis and upper bound technique is employed to assess temperature field and thermal stress distribution within the work rolls during continuous hot strip rolling process. Two-dimensional finite element analysis is utilised to simultaneously predict temperature fields within the rolling metal and the work roll as well as thermal stresses in the work rolls. In order to calculate the velocity field and the rate of heat of deformation, an upper bound solution is coupled with the employed finite element analysis. The utilised model makes it possible to estimate the effects of different parameters such as idling revolutions and initial temperature on...
An integrated model for prediction of thermo-mechanical behaviour of metal and work-rolls during hot strip rolling process
, Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 223, Issue 4 , 2009 , Pages 395-407 ; 09544054 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
2009
Abstract
In this paper an integrated model has been developed that is capable of considering the effects of process parameters on the thermo-mechanical behaviour of the work-roll and the strip during hot rolling operations. The commercially finite element package ABAQUS is utilized to solve the governing equations, while an elasto-viscoplastic material behaviour is utilized in the model. The model may be employed in single-pass as well as multi-pass rolling layouts. Various aspects of the hot rolling process are predicted including temperature field and thermo-mechanical stresses within the work-roll as well as temperature, strain, and residual stresses distributions within the strip. To assess the...
Effects of interface conditions on thermo-mechanical fields of multi-phase nano-fibers/particles
, Article Journal of Thermal Stresses ; Volume 32, Issue 11 , 2009 , Pages 1166-1180 ; 01495739 (ISSN) ; Shodja, H. M ; Sharif University of Technology
2009
Abstract
The stress field of a multi-phase spherical/cylindrical inhomogeneity with arbitrary interface bonding conditions, subjected to both a uniform temperature change and a uniform hydrostatic tension, is presented. Imperfect bonding conditions are modeled using linear spring model and coherent interface model. In nanosize inhomogeneities, since the surface energy is not negligible with respect to the bulk energy, the effect of surface stresses is incorporated into the formulation. Accurate estimates for the thermal stresses of a functionally graded coated inhomogeneity with perfect and /~or imperfect interfaces are given. The influence of coating stiffness, coating thickness and interface...
Design of thick-walled cylindrical vessels under internal pressure based on elasto-plastic approach
, Article Materials and Design ; Volume 30, Issue 9 , 2009 , Pages 3537-3544 ; 02641275 (ISSN) ; Kargarnovin, M. H ; Naghdabadi, R ; Sharif University of Technology
2009
Abstract
By considering the Bauschinger effect and the yield criterion of Tresca, an exact elasto-plastic analytical solution for a thick-walled cylindrical vessel made of elastic linear-hardening material is derived. Having the working pressure and geometric dimensions of the vessel, the distribution of the hoop and equivalent stresses are optimized in the way that the distribution of stresses becomes smooth in the vessel wall. Based on two optimizing methods of the hoop and equivalent stresses, the best autofrettage pressure is determined. It is shown that this pressure is more than the working pressure and depends on the three following variables: Bauschinger effect, working pressure and geometric...