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Total 30 records

    A time-dependent finite element formulation for thick shape memory polymer beams considering shear effects

    , Article International Journal of Applied Mechanics ; Volume 10, Issue 4 , 2018 ; 17588251 (ISSN) Eskandari, A. H ; Baghani, M ; Sohrabpour, S ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2018
    Abstract
    In this paper, employing a thermomechanical small strain constitutive model for shape memory polymers (SMP), a beam element made of SMPs is presented based on the kinematic assumptions of Timoshenko beam theory. Considering the low stiffness of SMPs, the necessity for developing a Timoshenko beam element becomes more prominent. This is due to the fact that relatively thicker beams are required in the design procedure of smart structures. Furthermore, in the design and optimization process of these structures which involves a large number of simulations, we cannot rely only on the time consuming 3D finite element analyses. In order to properly validate the developed formulations, the numeric... 

    Shear band propagation in honeycombs: numerical and experimental

    , Article Rapid Prototyping Journal ; Volume 24, Issue 2 , 2018 , Pages 477-484 ; 13552546 (ISSN) Goodarzi Hosseinabadi, H ; Bagheri, R ; Altstadt, V ; Sharif University of Technology
    Emerald Group Publishing Ltd  2018
    Abstract
    Purpose: Hexagonal honeycombs with meso-metric cell size show excellent load bearing and energy absorption potential, which make them attractive in many applications. However, owing to their bend-dominated structure, honeycombs are susceptible to deformation localization. The purpose of this study is to provide insight about shear band propagation in struts of 3D-printed honeycombs and its relation to the achieved macroscopic mechanical behavior. Design/methodology/approach: Hexagonal honeycombs and unit cell models are 3D-printed by fused deposition modeling (FDM). The samples are exposed to compression loading and digital image correlation technique and finite element analyses are... 

    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) Rezaei Farkoosh, A ; 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... 

    Effect of thermal cycles on mechanical response of pultruded glass fiber reinforced polymer profiles of different geometries

    , Article Composite Structures ; Volume 223 , 2019 ; 02638223 (ISSN) Jafari, A ; Ashrafi, H ; Bazli, M ; Ozbakkaloglu, T ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    This study investigates the effect of Thermal cycles on the mechanical properties of GFRP pultruded profiles with different geometries. Bending specimens consisted of I-shaped and U-channel profiles that were tested in three-point bending along their both principal weak and strong axes, whereas box profiles and laminates were used in compression and tension tests, respectively. Each specimen was exposed to a range of thermal cycles, between −20 °C and 20 °C. The failure modes of the profiles were closely investigated at both major and minor scales. Results were analyzed using ANOVA to determine the influence of each factor and a model was developed to predict the strength retention of... 

    Effects of material properties estimations on the thermo-elastic analysis for functionally graded thick spheres and cylinders

    , Article ASME International Mechanical Engineering Congress and Exposition, IMECE 2007, Seattle, WA, 11 November 2007 through 15 November 2007 ; Volume 10 PART B , 2008 , Pages 843-846 ; 0791843041 (ISBN); 9780791843048 (ISBN) Ghaderi, P ; Bankehsaz, M ; Sharif University of Technology
    2008
    Abstract
    In this paper effects of material properties estimations, used for particulate reinforced composites, on the thermo-mechanical response of functionally graded sphere and cylinder are presented. A numerical solution for an arbitrary material gradation is obtained for each geometry independently. With this assumption, the governing partial differential equations are reduced to an ordinary differential equation in each geometry. The thermo-elastic solution for hollow sphere is derived using spherical symmetry. However, plane strain and axial symmetry are assumed for solving hollow cylinder. In the numerical method, radial domain is divided into some finite sub-domains and material properties... 

    Effect of pore geometry and loading direction on deformation mechanism of rapid prototyped scaffolds

    , Article Acta Materialia ; Volume 60, Issue 6-7 , 2012 , Pages 2778-2789 ; 13596454 (ISSN) Amirkhani, S ; Bagheri, R ; Zehtab Yazdi, A ; Sharif University of Technology
    2012
    Abstract
    Rapid prototyping is a promising technique for producing tissue engineering scaffolds due to its capacity to generate predetermined forms and structures featuring distinct pore architectures. The objective of this study is to investigate the influences of different pore geometries and their orientation with respect to the compressive loading direction on mechanical responses of scaffolds. Plastic models of scaffolds with cubic and hexagonal unit cells were fabricated by three-dimensional (3-D) printing. An in situ imaging technique was utilized to study the progressive compressive deformation of the scaffold models. In both cubic and hexagonal geometries, organized buckling patterns relevant... 

    Optimum groove pressing die design to achieve desirable severely plastic deformed sheets

    , Article Materials and Design ; Volume 31, Issue 1 , 2010 , Pages 94-103 ; 02641275 (ISSN) Kazeminezhad, M ; Hosseini, E ; Sharif University of Technology
    2010
    Abstract
    In this paper, considering the problems of common finite element (FE) codes that consider simple constitutive equations, a developed FE code that considers a new constitutive model is used to simulate the behavior of copper sheets under severe plastic deformation (SPD). The new proposed constitutive model, that considers dislocation densities in cell interiors and cell walls of material as true internal state variables, can investigate all stages of flow stress evolution of material during large plastic deformations and also can explain the effects of strain rate magnitude on the mechanical response of material, during room temperature SPD. The proposed FE analysis is used to investigate the... 

    Healthy and diseasedin vitromodels of vascular systems

    , Article Lab on a Chip ; Volume 21, Issue 4 , 2021 , Pages 641-659 ; 14730197 (ISSN) Hosseini, V ; Mallone, A ; Nasrollahi, F ; Ostrovidov, S ; Nasiri, R ; Mahmoodi, M ; Haghniaz, R ; Baidya, A ; Salek, M. M ; Darabi, M. A ; Orive, G ; Shamloo, A ; Dokmeci, M. R ; Ahadian, S ; Khademhosseini, A ; Sharif University of Technology
    Royal Society of Chemistry  2021
    Abstract
    Irregular hemodynamics affects the progression of various vascular diseases, such atherosclerosis or aneurysms. Despite the extensive hemodynamics studies on animal models, the inter-species differences between humans and animals hamper the translation of such findings. Recent advances in vascular tissue engineering and the suitability ofin vitromodels for interim analysis have increased the use ofin vitrohuman vascular tissue models. Although the effect of flow on endothelial cell (EC) pathophysiology and EC-flow interactions have been vastly studied in two-dimensional systems, they cannot be used to understand the effect of other micro- and macro-environmental parameters associated with... 

    Search for critical loading condition of the spine-A meta analysis of a nonlinear viscoelastic finite element model

    , Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 8, Issue 5 , 2005 , Pages 323-330 ; 10255842 (ISSN) Wang, J. L ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
    2005
    Abstract
    The relative vulnerability of spinal motion segments to different loading combinations remains unknown. The meta-analysis described here using the results of a validated L2-L3 nonlinear viscoelastic finite element model was designed to investigate the critical loading and its effect on the internal mechanics of the human lumbar spine. A Box-Behnken experimental design was used to design the magnitude of seven independent variables associated with loads, rotations and velocity of motion. Subsequently, an optimization method was used to find the primary and secondary variables that influence spine mechanical output related to facet forces, disc pressure, ligament forces, annulus matrix... 

    Examination of chondroitinase ABC I immobilization onto dextran-coated Fe3O4 nanoparticles and its in-vitro release

    , Article Journal of Biotechnology ; Volume 309 , 2020 , Pages 131-141 Askaripour, H ; Vossoughi, M ; Khajeh, K ; Alemzadeh, I ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    Chondroitinase ABC I (cABC I) has received notable attention in treatment of spinal cord injuries and its application as therapeutics has been limited due to low thermal stability at physiological temperature. In this study, cABC I enzyme was immobilized on the dextran-coated Fe3O4 nanoparticles through physical adsorption to improve the thermal stability. The nanoparticles were characterized using XRD, SEM, VSM, and FTIR analyses. Response surface methodology and central composite design were employed to assess factors affecting the activity of immobilized cABC I. Experimental results showed that pH 6.3, temperature 24 °C, enzyme/support mass ratio 1.27, and incubation time 5.7 h were the...