Search for: mechanical-behaviour
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    Effect of cyclic loading on the temporomandibular joint

    , Article Lecture Notes in Engineering and Computer Science ; Volume 1 , 2014 , Pages 655-658 ; ISSN: 20780958 ; ISBN: 9789881925275 Muhandiram, J ; Wang, B ; Chizari, M ; Sharif University of Technology
    This research is aiming to investigate the mechanical behaviour of the temporomandibular joint (TMJ), in response to kinematics/cyclical loading caused through actions of speech and mastication. A set of in-vitro experimental tests has been performed in three different groups on a fresh sheep jaw bone to examine the hypothesis of the study. No failure was monitored during the cyclical test. The study was concluded that the amount of loading is effective on the displacement of the TMJ  

    Modeling the Thermomechanical Behaviour of Shape Memory Materials Using Analytical and Numerical Methods

    , M.Sc. Thesis Sharif University of Technology Taghikhani, Yaser (Author) ; Karimi Taheri, Ali (Supervisor)
    Shape memory materials are a kind of smart materials which recently have been used in a wide range of fields in particular medicine and aerospace. These materials can be divided to shape memory polymers and shape memory alloys. The basis of shape memory alloys’ properties is a thermoelastic martensitic transformation taking place between a high symmetric phase, called Austenite, and a low symmetric phase, called Martensite. In this project, by means of finite element methods, continuum thermomechanics and selection of appropriate internal variables (such as amount and orientation of volumetric fraction of each phase) and control variables (like strain, stress, temperature and entropy), their... 

    Dynamic behaviours of carbon nanotubes under dc voltage based on strain gradient theory

    , Article Journal of Physics D: Applied Physics ; Volume 46, Issue 40 , 2013 ; 00223727 (ISSN) Fakhrabadi, M. M. S ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
    The paper deals with scrutinizing the vibration and dynamic pull-in behaviours of carbon nanotubes with different dimensions and boundary conditions. The strain gradient theory as a nonclassical elasticity theorem is applied in this research to compensate the limitations of the classical theories in predicting the mechanical behaviours of the micro- and nanostructures in general and carbon nanotubes, in particular under electrostatic actuation. The results reveal that the mechanical properties of carbon nanotube (CNTs) computed using the strain gradient theory differ significantly with those obtained from the classical theory. The strain gradient theory leads to higher stiffness and pull-in... 

    A novel laparoscopic grasper with two parallel jaws capable of extracting the mechanical behaviour of soft tissues

    , Article Journal of Medical Engineering and Technology ; Volume 41, Issue 5 , 2017 , Pages 339-345 ; 03091902 (ISSN) Nazarynasab, D ; Farahmand, F ; Mirbagheri, A ; Afshari, E ; Sharif University of Technology
    Taylor and Francis Ltd  2017
    Data related to force-deformation behaviour of soft tissue plays an important role in medical/surgical applications such as realistically modelling mechanical behaviour of soft tissue as well as minimally invasive surgery (MIS) and medical diagnosis. While the mechanical behaviour of soft tissue is very complex due to its different constitutive components, some issues increase its complexity like behavioural changes between the live and dead tissues. Indeed, an adequate quantitative description of mechanical behaviour of soft tissues requires high quality in vivo experimental data to be obtained and analysed. This paper describes a novel laparoscopic grasper with two parallel jaws capable of... 

    Thermo-mechanical Modeling of Angular Contact Ball-Bearings in High Speed Machine Tool Spindles

    , M.Sc. Thesis Sharif University of Technology Zahedi, Ali (Author) ; Movahhedy, Mohammad Reza (Supervisor)
    Machining in its general concept forms the major part of manufacturing processes regarding time and cost. Therefore any progress in machining techniques would be well beneficial. High speed machining is one of the recent concepts in machining technology which has attracted much attention and effort. But high speed spindles as the main part of high speed machines, have been notorious for their lack of reliability and sudden failure which originates mostly from thermal problems. In order to ensure reliable operation of spindles it is necessary to predict thermo-mechanical behavior of machine-tool spindles. The major sources of heat in a spindle are angular contact ball bearings (the most... 

    Effect of specimen's age on mechanical properties of plastic concrete walls in dam foundations

    , Article Electronic Journal of Geotechnical Engineering ; Volume 17 D , 2012 , Pages 473-482 ; 10893032 (ISSN) Jafarzadeh, F ; Mousavi, S. H ; Sharif University of Technology
    According to available information and references, water leakage and internal erosion in bodies and foundations of embankment dams are the main reasons of many problems and failures. To reduce this risk in foundation, plastic cut off walls is one of the most reliable solutions. In this research the effect of specimen's age on the mechanical properties of plastic concrete was studied. This paper summarizes the test results which were conducted in unconfined and triaxial state. Plastic concrete specimens were prepared in the laboratory condition using the materials provided from the Silve dam site. Test results have shown that the time and confining pressure extremely affect the mechanical... 

    Stability analysis of carbon nanotubes using a hybrid atomistic-structural element

    , Article International Journal of Nanomanufacturing ; Volume 5, Issue 3-4 , 2010 , Pages 366-375 ; 17469392 (ISSN) Sadeghi, M ; Naghdabadi, R ; Sharif University of Technology
    In this paper, a hybrid atomistic-structural element for studying the mechanical behaviour of carbon nanotubes is introduced. Non-linear formulation for this element is derived based on empirical inter-atomic potentials. This hybrid element is capable of taking into account the non-linear nature of inter-atomic forces as well as the non-linearity arising from large deformations. Using these capabilities, the stability analysis of carbon nanotubes under axial compressive loading is performed and the post-buckling behaviour is predicted. Also, the dependence of axial buckling force on nanotube radius is shown  

    Dissimilar Al/steel friction stir spot welding: To penetrate into the lower steel sheet or not?

    , Article Science and Technology of Welding and Joining ; Volume 21, Issue 6 , 2016 , Pages 466-472 ; 13621718 (ISSN) Fereiduni, E ; Movahedi, M ; Kokabi, A. H ; Sharif University of Technology
    Taylor and Francis Ltd  2016
    There has always been a question about which condition results in superior mechanical properties in friction stir spot welds: (i) when the tool tip penetrates into the lower sheet or (ii) when the tool tip does not touch it. Given the question, the effects of the tool penetration depth were investigated on the microstructure and mechanical behaviour of dissimilar Al-5083/St-12 joints produced by friction stir spot welding (FSSW). Two different processes named as non-penetrating and penetrating FSSW were used. Optical and scanning electron microscopes as well as microhardness and tensile-shear tests were utilised to examine the obtained joints. The results showed that the penetrating process... 

    Friction stir lap joining of aluminium alloy to polypropylene sheets

    , Article Science and Technology of Welding and Joining ; Volume 22, Issue 2 , 2017 , Pages 120-126 ; 13621718 (ISSN) Shahmiri, H ; Movahedi, M ; Kokabi, A. H ; Sharif University of Technology
    Taylor and Francis Ltd  2017
    Joining feasibility of aluminium alloy to polypropylene sheets via friction stir lap joining was examined. Effects of heat-input on microstructure and mechanical behaviour of the joints were investigated. A covering plate was used to confine flow of molten polymer. The results showed a distinctive interaction layer at polymer/aluminium interface, consisted mainly of C, O and Al. Shear strength of the joints decreased by enhancement of the heat-input due to increase in the thickness of the interaction layer as well as the gap width between this layer and both aluminium and polymer matrices. Maximum shear-tensile strength of 5.1MPa (∼20% of polymer shear strength) was obtained, which was... 

    Numerical Investigation of the Effects of Different Parameters on the Mechanical Response of Energy Pile under Cyclic Thermal Loading in Saturated Clay

    , M.Sc. Thesis Sharif University of Technology Sadeghzadeh, Mohammad Reza (Author) ; Ahmadi, Mohammad Mehdi (Supervisor)
    Considering the environmental pollution caused by the consumption of fossil fuels, replacing clean and renewable energies instead of fossil fuels has become one of the most critical issues across the world. The use of energy geostructures, especially energy piles, to exchange the heat between the superstructures and the ground is one of the approaches for taking advantage of clean energy. In order to maintain the safety and the serviceability of structures built on energy piles, it is necessary to study the effects of heat exchange between energy piles and the ground on the mechanical behavior of energy piles, as well as the effects of various parameters on the interaction between energy... 

    Molecular dynamics investigation of β-SiC behavior under three-axial tensile loading

    , Article Journal of Computational and Theoretical Nanoscience ; Volume 8, Issue 11 , 2011 , Pages 2187-2192 ; 15461955 (ISSN) Mortazavi, B ; Simchi, A ; Besharati Givi, M. K ; Rajabpour, A ; Sharif University of Technology
    Molecular dynamics (MD) simulations were used to study the mechanical behaviour of β-SiC at nano-scale under tensile loading. Effects of loading rate and tensile temperature on the mechanical properties and failure were studied. Modified embedded-atom method (MEAM) potential and Berendsen thermostat were utilized for modelling. Periodic boundary conditions were employed and the behaviour of material was analyzed under three-axial loading condition at which the stress- strain relation was acceptably size independent. It is shown that with increasing the loading rate from 5 m/s to 70 m/s, the failure strain increases without a remarkable change in the stress-strain relationship. The MD... 

    Effects of free quartz on mechanical behaviour of kaolinite based geopolymers

    , Article Materials Technology ; Volume 26, Issue 2 , Jul , 2011 , Pages 96-99 ; 10667857 (ISSN) Yousefi, E ; Majidi, B ; Sharif University of Technology
    Quartz is usually detected as an impurity of kaolinite clays. The present work attempts to evaluate the role and behaviour of quartz particles in geopolymerisation and its probable effects on mechanical behaviour of geopolymeric products. Two kaolinite clays with different free quartz contents were used as raw materials to produce geopolymers. Results showed that using high content quartz kaolin causes higher compressive strength. Scanning electron microscopy studies confirmed that quartz does not participate in geopolymerisation and completely remains in the structure as fine particles. High hardness quartz particles by retarding crack growth in the geopolymer matrix enhance mechanical... 

    Friction stir soldering: a novel route to produce graphite-copper dissimilar joints

    , Article Materials and Design ; Volume 116 , 2017 , Pages 599-608 ; 02641275 (ISSN) Ebrahimian, A ; Kokabi, A. H ; Sharif University of Technology
    Elsevier Ltd  2017
    In this study, friction stir soldering (FSS) as an emerging joining process with the aid of a preliminary electroplating process was utilized for the first time to fabricate graphite-copper lap joints aimed at investigation of rotational speed influence on joint interface microstructure and mechanical behaviour. To do so, an Sn-37Pb solder foil was placed between a copper sheet and a copper-coated graphite substrate after which a rotating pin-free tool was plunged into the copper sheet and allowed to travel along the joint. Results indicated that adhesive strength between the electroplated copper coating and graphite substrate was strongly affected by surface roughness and plating current... 

    Mechanical behaviour of A-III steel rebars under monotonic loadings at seismic strain rates

    , Article Magazine of Concrete Research ; Volume 70, Issue 1 , 2018 , Pages 42-54 ; 00249831 (ISSN) Khonsari, S. V ; Shabani, A ; England, G. L ; Shahsavar Gargari, M ; Sharif University of Technology
    ICE Publishing  2018
    As the reinforcing bars used in concrete structures located in earthquake-prone areas experience strain rates higher than normal quasi-static ones, it is necessary to have a comprehensive understanding of the behaviour of such materials under these rates of loading. In this work, in order to study the behaviour of grade A-III reinforcing-bar steel (based on the GOST standard, a set of technical standards maintained by the Euro-Asian Council for Standardization, Metrology and Certification), a number of monotonic tests on its tensile and compressive strength on (short and long) specimens at various strain rates, 0·002, 0·01, 0·02 and 0·04 s-1, experienced during earthquakes, were carried out.... 

    Relationship between failure behaviour and weld fusion zone attributes of austenitic stainless steel resistance spot welds

    , Article Materials Science and Technology ; Volume 24, Issue 12 , 2008 , Pages 1506-1512 ; 02670836 (ISSN) Marashi, P ; Pouranvari, M ; Sanaee, M. H ; Abedi, A ; Abootalebi, H ; Goodarzi, M ; Sharif University of Technology
    Resistance spot welding was used to join austenitic stainless steel sheets. Mechanical properties of the spot welds were evaluated using tensile shear test. Mechanical behaviour was described by peak load, failure energy and failure mode. The relationship between weld fusion zone attributes and failure behaviour was studied. Generally, it was observed that increasing fusion zone size is accompanied by an increase in load carrying capacity and energy absorption capability. However, when expulsion occurs, despite almost constant weld fusion zone size, energy absorption capability reduces significantly due to increase in electrode indentation depth. Considering the failure location and failure...