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energy-absorbents
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Energy absorption in plastic expansion of circular metal tubes
, Article Computational Plasticity X - Fundamentals and Applications, 2 September 2009 through 4 September 2009, Barcelona ; 2009 ; 9788496736696 (ISBN) ; Salehghaffari, S ; Sharif University of Technology
Abstract
This paper investigates a new method of dissipating energy in which a rigid tube is driven into the deformable tube under axial compression. Since there is a specific clearance between the rigid and deformable tubes, the deformable tube is expanded during axial compression, and the impact energy is absorbed by plastic expansion of deformable tube and frictional energy between deformable and rigid tubes. Quasi-static axial compression tests with different values of friction coefficient between rigid and deformable tubes are performed. Theoretical formulation with consideration of strain hardening effect is presented to predict the mean crushing load. Theoretical and experimental studies show...
On the improvement of steel plate shear wall behavior using energy absorbent element
, Article Scientia Iranica ; Volume 24, Issue 1 , 2017 , Pages 11-18 ; 10263098 (ISSN) ; Mofid, M ; Sharif University of Technology
Sharif University of Technology
2017
Abstract
Structural engineers have recognized unstiffened Steel Plate Shear Wall (SPSW) as an economical lateral resisting system due to the post-buckling capacity, energy dissipation, and deformability. This study investigates practical application of an added Energy Absorbent Element (EAE), subjoined to the SPSW in order to improve seismic behavior of the SPSW. The EAE is an aluminum shear panel with or without bracings and surrounding frame. Furthermore, a series of parametric studies are implemented to examine the effect of dimensions, position, and formation of the EAE. It is assumed that the lateral loading is applied as quasi-static loading. Further, nonlinearity of the material and the...
Design and Construction of Ocean Wave Energy Converter
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohammad Saeid (Supervisor) ; Abbaspour, Mohammad (Supervisor)
Abstract
An important characteristic of sea waves is their high energy density, which is the highest among renewable energy sources. Many different types of wave-energy converters of various categories have been proposed yet. In this thesis the performance of a novel wave energy converter (WEC) is studied. The system, extracts the wave energy from heaving motion of a cylinder buoy in head seas. This heaving cylindrical floating buoy is tested with sinusoidal incident waves in a wave channel in marine engineering laboratory, Sharif University of Technology (SUT). The study begins with a thorough review on types of renewable energy and their application in Iran. Then an introduction to ocean wave,...
Investigation of membrane preparation condition effect on the PSD and porosity of the membranes using a novel image processing technique
, Article Journal of Applied Polymer Science ; Volume 131, Issue 4 , 15 February , 2014 ; ISSN: 00218995 ; Samimi, A ; Mousavi, S. A ; Bozarjamhari, R. B ; Sharif University of Technology
Abstract
A totally computerized image processing program package is developed to analyze the SEM images of membrane surface and cross-section. Pore size distribution and porosity of the fabricated membranes are determined using the proposed image processing procedure. Furthermore, effect of coagulation bath temperature on the morphology and mechanical properties (such as tensile strength, strain break, tensile energy absorbent, and tensile stiffness) of Polysulfone (PSf) membranes are investigated. The results reveal that the mechanical properties are higher when N-methyl-2-pyrrolidone (NMP) is used as solvent. Also, an increase in the coagulation bath temperature caused a monotonous increase in the...
Optimizing structural and mechanical properties of coiled carbon nanotubes with nsga-ii and reactive molecular dynamics simulation
, Article Journal of Physical Chemistry C ; Volume 125, Issue 11 , 2021 , Pages 6237-6248 ; 19327447 (ISSN) ; Rangriz, F ; Karimi Taheri, A ; Abdi Jalebi, M ; Sharif University of Technology
American Chemical Society
2021
Abstract
Coiled carbon nanotubes (CCNTs) have increasingly become a vital factor in the new generation of nanodevices and energy-absorbing materials due to their outstanding properties. Here, the multiobjective optimization of CCNTs is applied to assess their mechanical properties. The best trade-off between conflicting mechanical properties (e.g., yield stress and yield strain) is demonstrated and the optimization of the geometry enables us to find the astonishing CCNTs with a stretchability of 400%. These structures have been recognized for the first time in the field. We derived several highly accurate analytical equations for the yield stress and yield strain by the implementation of...
The Effects of PTO Characteristics on Performance of a Floating Point Absorber Wave Energy Converter
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mahdi (Supervisor) ; Abazari, Abuzar (Supervisor)
Abstract
In recent years, the challenges of using fossil energy causes governments and researchers to focus on renewable energies. In this regard, one of the strategies for generating power is using wave energy converters. The aim of present study is modeling frequency and time domain analysis of the wave energy converter. the study focuses on the effect of Power-Take-Off system on the output power and efficiency under the Macoran sea waves. First, the concept of wave converters is explained and the commercialized ones are introduced. Then the related previous works are reviewed and the wave theories are briefly presented. In the following, a specified one-degree-of-freedom converter is modeled in...
Optimization of functionally graded materials in the slab symmetrically surface heated using transient analytical solution
, Article Journal of Thermal Stresses ; Vol. 37, issue. 2 , February , 2014 , pp. 137-159 ; ISSN: 01495739 ; Taati, E ; Tabrizi, H. B ; Sharif University of Technology
Abstract
Functionally graded materials (FGMs) have been introduced to significantly reduce the temperature and thermal stresses on structures at severe thermal loading. Design and development of FGMs as the heat treatable and energy-absorbing materials for high-temperature and thermal protection systems requires understanding of exact temperature and thermal stress distribution, in order to optimize their resistance to failure. In this study, transient temperature and associated thermal stresses in a functionally graded slab symmetrically heated on both sides are determined by separation of the variables scheme. This method is applied to the heat conduction equation in terms of heat flux for...