Search for: energy-absorption
0.007 seconds
Total 81 records

    A modified approach to determine the energy dissipation capacity of the basic folding mechanism

    , Article Thin-Walled Structures ; Volume 41, Issue 9 , 2003 , Pages 835-848 ; 02638231 (ISSN) Vafai, A ; Shahbeyk, S ; Kamalan, A ; Sharif University of Technology
    In this paper, new assumptions are made to determine the energy dissipation capacity of the basic folding mechanism. The basic folding mechanism, introduced by Wierzbicki and Abramowiciz is an intelligent mathematical imitation of the real crumpling process for simple structural sections. A contribution factor for some part of energy absorption and the new concept of varying rolling radios, based on minimizing instantaneously applied load, are utilized to enrich the old analytical solution. A set of finite element analyses on the axial collapse of square boxcolumns with various cross sections and width to thickness ratios, has been performed to verify the proposed analytical solution vs. the... 

    Passive cooling effects of courtyards

    , Article Building and Environment ; Volume 40, Issue 1 , 2005 , Pages 89-104 ; 03601323 (ISSN) Safarzadeh, H ; Bahadori, M. N ; Sharif University of Technology
    The passive cooling effects of a courtyard of a small building were determined numerically, employing an energy-analysis software developed for that purpose. The passive cooling features considered were the shading effects of courtyard walls and two large trees (of various shapes) planted immediately next to the south wall of the building, the presence of a pool, a lawn and flowers in the yard, and the wind shading effects of the walls and trees. It was found that these features alone cannot maintain thermal comfort during the hot summer hours in Tehran, but reduce the cooling energy requirements of the building to some extent. They have an adverse effect of increasing the heating energy... 

    Experimental studies on thin-walled grooved tubes under axial compression

    , Article Experimental Mechanics ; Volume 44, Issue 1 , 2004 , Pages 101-108 ; 00144851 (ISSN) Hosseinipour, S. J ; Daneshi, G. H ; Sharif University of Technology
    SAGE Publications Inc  2004
    We study experimentally the axial crushing behavior and crashworthiness characteristics of thin-walled steel tubes containing annular grooves. The grooves determine the positions of the folds and control the buckling mode of deformation. In the present work we aim to improve the uniformity of the load-displacement behavior and to predict the energy absorption capacity of the tubes. Grooves are cut circumferentially and alternately inside and outside the tubes at predetermined intervals. Quasi-static axial crushing tests are performed with different groove distances. Photographs are taken during axial buckling and the specimens after crushing are sectioned axially to carry out the... 

    Energy absorbtion and mean crushing load of thin-walled grooved tubes under axial compression

    , Article Thin-Walled Structures ; Volume 41, Issue 1 , 2003 , Pages 31-46 ; 02638231 (ISSN) Hosseinipour, S. J ; Daneshi, G. H ; Sharif University of Technology
    Elsevier Ltd  2003
    In the present study, crashworthiness characteristics of thin-walled steel tubes containing annular grooves are studied. For this purpose, the grooves are introduced in the tube to force the plastic deformation to occur at predetermined intervals along the tube. The aims are controlling the buckling mode and predicting energy absorption capacity of the tubes. To do so, circumferential grooves are cut alternately inside and outside of the tubes at predetermined intervals. Quasi-static axial crushing tests are performed and the load-displacement curves are studied. Theoretical formulations are presented for predicting the energy absorption and mean crushing load. It is found a good agreement... 

    Behavior prediction of corrugated steel plate shear walls with openings

    , Article Journal of Constructional Steel Research ; Volume 114 , 2015 , Pages 258-268 ; 0143974X (ISSN) Farzampour, A ; Laman, J. A ; Sharif University of Technology
    Elsevier Ltd  2015
    Corrugated steel plate and simple steel plate shear wall construction is a widely accepted and efficient lateral force resisting construction. The widespread use is motivated by the large initial stiffness, high level of energy absorption, and ability to accommodate openings. There is a dearth of information regarding the detailed nonlinear, inelastic behavior of corrugated steel plate shear walls, particularly walls with openings. Presented here are the results of a detailed, numerical parametric study comparing corrugated steel plate and simple steel plate shear walls, with and without openings. Parameters studied are plate thickness, angle of corrugation, opening size, and opening... 

    Experimental and numerical studies on ribbed bracing system

    , Article Structural Design of Tall and Special Buildings ; Volume 27, Issue 13 , 2018 ; 15417794 (ISSN) Arzeytoon, A ; Toufigh, V ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    Ribbed bracing system (RBS) is an innovative structural system designed to eliminate the buckling of braces and enhance the behavior of structures under seismic loads. In this study, a collaborative performance of 2 RBS devices bracing a frame was assessed numerically and experimentally. In the numerical phase, the collaboration of ribbed braces at various stages of reversal loading was elaborated mathematically and was used for representing the system using finite element modeling. In the next phase, the numerically observed behavior was validated experimentally by conducting cyclic quasistatic tests of the proposed configurations. Two alternative RBS configurations—called completely closed... 

    Experimental and numerical study on a novel ribbed bracing system

    , Article Advances in Structural Engineering ; Volume 21, Issue 9 , 2018 , Pages 1349-1360 ; 13694332 (ISSN) Golafshani, A. A ; Fallah, S ; Sahafipourfard, M. A ; Arzeytoon, A ; Toufigh, V ; Sharif University of Technology
    SAGE Publications Inc  2018
    In this article, the ribbed bracing system is proposed and evaluated through experimental and numerical studies. Ribbed bracing system is composed of a supplemental part with ribbed interfaces that is attached to a brace member and allows for its free length reduction to prevent the development of compressional forces responsible for buckling of the brace. Ribbed bracing system provides two different mechanisms: completely closed ribbed bracing system and improved-centering ribbed bracing system which are validated, in this study, through design, fabrication, and testing of small-scale specimens subjected to cyclic quasi-static loading. As verified by the test results, in improved-centering... 

    Electromechanical energy absorption, resonance frequency, and low-velocity impact analysis of the piezoelectric doubly curved system

    , Article Mechanical Systems and Signal Processing ; Volume 157 , 2021 ; 08883270 (ISSN) Guo, Y ; Mi, H ; Habibi, M ; Sharif University of Technology
    Academic Press  2021
    In this research, electrically performance, vibration/resonance characteristics, low-velocity impact, and absorbed energy of the piezoelectric doubly curved panel on the viscoelastic substrate is carried out. For modeling the contact force between the structure and impactor, Hertz contact theory is presented. Hamilton's principle and first-order shear deformation theory (FSDT) are presented for obtaining the governing and boundary condition equations of the structure under the low-velocity impact. Galerkin and Newmark solution procedures are presented for solving the governing equation in displacement, and time domains, respectively. This study's novelty is considering the effect of... 

    Assessment of fiber-reinforcement and foam-filling in the directional energy absorption performance of a 3D printed accordion cellular structure

    , Article Composite Structures ; Volume 297 , 2022 ; 02638223 (ISSN) Farrokhabadi, A ; Mahdi Ashrafian, M ; Behravesh, A. H ; Kaveh Hedayati, S ; Sharif University of Technology
    Elsevier Ltd  2022
    This paper presents an evaluation of two distinct techniques to improve energy absorption capability of an accordion cellular structure with close-to-zero Poisson's ratio. For this purpose, fiber-reinforcement and foam-filling methods were employed to address the material enhancement and to obtain light and tough structures with high specific energy absorption. Employing an innovated additive manufacturing based on material extrusion process, specimens of glass fiber-reinforced PLA were produced in both in-plane directions to compare with the un-reinforced counterpart. In continue, some of the 3D printed samples were strengthened by means of polyurethane foam in their hollow structure. The... 

    Experimental and Numerical Study of Penetration in Sandwich Structure with Ceramic Core

    , M.Sc. Thesis Sharif University of Technology Mazaheri, Hashem (Author) ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor)
    In this research, penetration in a new confined ceramic-metal structure is studied experimentally and numerically. In this new structure, ceramic tile is confined on its front face by an aluminum foil. First, penetration experiment in 5 mm thick Al 1100 plate carried out. The ballistic limit velocity is obtained about 140 m/s. The difference between experiment and numerical simulation is lower than 5 percent. Then penetration analysis of 10 mm thick Alumina tiles is carried out experimentally and numerically in confined and unconfined conditions. Ceramic tiles are in square shape with 50 mm side length. The ballistic limit velocity for unconfined and confined ceramic tiles are obtained about... 

    A New, replaceable Steel Connection with High Energy Absorbing Capacity

    , M.Sc. Thesis Sharif University of Technology Parvinnia, Mohammad Hossein (Author) ; Khansari, Vahid (Supervisor)

    Investigation of Thickness Influences On Energy Absorption For Side Doors And B Pillar In Euro NCAP Pole Side Impact Test

    , Article Applied Mechanics and Materials ; Vol. 663, issue , Oct , 2014 , p. 585-589 Lilehkoohi, A. H ; Faieza, A. A ; Sahari, B. B ; Nuraini, A. A ; Halali, M ; Sharif University of Technology
    To assess a car under the Euro New Car Assessment Program (Euro-NCAP), Adult Occupant Protection is one out of three parameters which need to be calculated with a weight factor of 50% while the other parameters, Child Occupant Protection and Pedestrian Occupant Protection, have a weight factor of 20%. The Pole Side Impact Test, beside two other tests, Side and Front Impact, is also required to calculate the Adult Occupant Protection. It shows how important the Pole Side Impact Test is and what an effective role it has in the car rating assessment. In this paper, the objective is to evaluate the effect of thickness on the energy absorbed by the side doors and the B pillar and its... 

    Nonlinear seismic behavior of RC frames with RC braces

    , Article Asian Journal of Civil Engineering ; Volume 9, Issue 6 , 2008 , Pages 577-592 ; 15630854 (ISSN) Khaloo, A. R ; Mohseni, M. M ; Sharif University of Technology
    Braced frames, besides other structural systems, such as moment resisting frames or shear walls, have been an effective and valuable method to enhance structures against lateral loads. In wind or seismic excitations, inclined elements react as truss web elements which would bear compression or tension stresses. This axial reaction results in less moments and therefore smaller sizes in beam and column sections with respect to members in similar moment resisting frame. However, low tensile strength of concrete material, made it a challenge to use in inclined members. In practice, there have been various methods to consider this defect such as disengagement of brace elements in tension or... 

    Using Finite Element Method for Analyzing the Performance of Low Yield Point Steel Plate Shear Wall

    , M.Sc. Thesis Sharif University of Technology Jebelli, Houtan (Author) ; Mofid, Massoud (Supervisor)
    Steel plate shear walls are lateral load resisting systems, especially against earthquake excitation. They are constructed with or without stiffeners. Stiffened walls are more ductile than without stiffeners walls. In this research, nine thin steel plate shear walls models were considered in three groups of 5story, 01story and 05 story walls. In each group different yield point steel for the infill plate was used. The results showed that, using low yield point(LYP) steel will increase energy dissipation of models up to %36. LYP also improve shear capacity of models up to %96. The results showed that using LYP will cause lower lateral displacement in models  

    Revision, Modification, Fabrication, and Examining the Behavior of Ribbed Bracing System (RBS)under Test

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Hossein (Author) ; Golafshani, Ali Akbar (Supervisor) ; Toufigh, Vahab (Supervisor)
    As a result of numerous earthquakes happened in recent decades, widespread failures were observed in conventional braced frames, which were mostly created due to buckling of the braces under compression. To find a solution to overcome this problem, Ribbed Bracing System (RBS) was developed by Golafshani et al. in 2004. In this study, continuing the experimental investigation and considering the previous outcomes, the RBS bracing was redesigned based on some modifications. Then, two half-scale RBS braces with pinned frames were constructed and tested under cyclic loading. RBS systems were utilized in two options, CC-RBS and SC-RBS, in X configuration, the first of which was constantly... 

    Numerical Study of the Behavior of Two-Dimensional Materials with Microstructure Bistability

    , M.Sc. Thesis Sharif University of Technology Talebpour Parizi, Mohammad (Author) ; Arghavani Hadi, Jamal (Supervisor)
    In the present study, the energy absorption mechanism is presented that used in two-dimensional microstructures. By studying the angular geometric parameters and the narrow ratio of the tilted members, we can use the property of the geometry of the structure to be bistable. In this way, there can be two stable geometries with different energies, which enters energy into the structure, such as the phase transformation to the second geometry that has more energy. By changing the geometric parameters, the deformed state can be stable or unstable. Because of the complex geometries that exist in this mechanism, additive production methods are more effective than geometric ratios or sharp points... 

    An Investigation of the Effects of Zipper Strut on the Cost and Energy Dissipation Capacity of Concentrically & Eccentrically Chevron Braced Systems

    , M.Sc. Thesis Sharif University of Technology Dehghany Yazdeli, Mahdi (Author) ; Ahmadizadeh, Mehdi (Supervisor)
    Concentric and eccentric chevron braces are among the more economical lateral force resisting systems for structures. However, chevron braced systems are prone to concentration of damage in a single story and formation of soft stories when buckling occurs in the bracing elements. This leads to a gradual loss in the structural performance, particularly as the height of the structure increases. One of the most notable methods to alleviate this problem and improve the structural performance is the addition of zipper struts to concentrically chevron braced frames that are known to improve the distribution of plastic energy dissipation along the height of the structure. While this usually... 

    An Investigation Into the Energy Absorption of Friction Stir Welded Aluminum

    , M.Sc. Thesis Sharif University of Technology Amiri, Mahsa (Author) ; Kazeminezhad, Mohsen (Supervisor) ; Kokabi, Amir Hossein (Supervisor)
    Friction stir welding (FSW) is an appropriate method for joining Aluminum structures. In this method lots of defects involved in other methods are not formed and good properties are achieved for Aluminum joints. The metal sheets joined by this method are used to manufacture metal structures bodies. One of the important issues in the structure bodies used in transportation is the amount of energy absorbed in collision with other objects. One of the methods to investigate the energy absorption is wedge tearing test and one other is tensile test. In the preset study two sheets of Al 1050 were joined using FSW method in different tool rotational and welding speeds. Firstly, the microstructure of... 

    , M.Sc. Thesis Sharif University of Technology Shahsavar, Morad (Author) ; Khonsari, Vahid (Supervisor)
    In this thesis, change of the behavior of frames due to adding damping devices to frames is taken into consideration and a non-linear static analysis computer program is developed . In numerical studies a few one and two story frames are used. The results of previous studies have shown that, adding energy damping devices to the structural systems, results in structure damping increase, story drift and base shear decrease. To reveal the behavior of the new bracing system, experimental and numerical studies are made. The main point in design of this bracing system, was the capability of easy replacement and maximum damping with minimum damage. It must be declared that design thought of this... 

    Investigating the Lowest Amount of Fibers in Improving the Strength and Ductility of Ultra-High-Performance Concrete

    , M.Sc. Thesis Sharif University of Technology Kamjou, Amir Shayan (Author) ; Khaloo, Alireza (Supervisor)
    It used to be widely accepted as a virtue in engineering society that, fibers are generally used as mechanism to resist cracking and increasing the strength of concrete in some cases. Since 1990, fibers are usually used in concrete to control cracking due to plastic shrinkage and to drying shrinkage. They also reduce the permeability and bleeding of concrete. Some types of fibers produce greater impact, abrasion and shatter-resistance in concrete. Studies turn this notion to cognition that among all types of existing fibers, Steel Fiber and Polypropylene Fiber resulted the highest improved behavior in concrete. The Ultra-High-Performance Concrete which heated the debate in recent papers...