Search for: rupture
Total 31 records
Article Proceedings of the ASME Summer Bioengineering Conference 2009, SBC2009, 17 June 2009 through 21 June 2009 ; Issue PART B , 2009 , Pages 817-818 ; 9780791848913 (ISBN) ; Tahmasebi, M. N ; Parnianpour, M ; Sharif University of Technology
Every year many people suffer from knee injuries. Previous studies on patients with knee injuries has shown that about 40% percent of knee injuries are ligament injuries, and about 50% of the ligament injuries are the Anterior Cruciate Ligament (ACL) injuries [1–2]. Knee arthrometers are widely used to diagnose ACL injuries, along with other methods [3–4]. In the current research, a knee arthrometer which was developed to provide an accurate measurement of AP displacement of the knee  was used to measure anterior laxity of the knees of 20 subjects, and the results were analyzed to find better criteria to diagnose ACL rupture using knee arthrometers
Practical properties and formaldehyde emission of medium density fiberboards (MDFs) recycled by electrical method, Article European Journal of Wood and Wood Products ; Volume 76, Issue 4 , 2018 , Pages 1287-1294 ; 00183768 (ISSN) ; Abdolkhani, A ; Doost hoseini, K ; Ramazani Saadat Abadi , A ; Tarmian, A ; Sharif University of Technology
Springer Verlag 2018
In this study, the performance of the electrical method in MDF wastes recycling was determined. For investigating the practical aspect of the electrical method, the hydrothermal method as a known recycling method was studied too. The recycling process by electrical method conducted for two different time durations (2 and 4 min) at a temperature of 100 °C and recycling using the hydrothermal method was done at a temperature of 105 °C for 150 min under 4 bar pressure with subsequent refining step. Recycled fibers were analyzed by determination of the chemical composition of fibers and fiber classification. After that, laboratory MDF boards with dimensions of 35 × 35 × 12 mm3 and density of...
An Experimental-Numerical Study of Penetration in Constrained Ceramic-Metal Structures Covered by Polymer Layer, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza ; Sohrabpour, Saeed
This thesis has been done in two parts. In part I,a rupture disc wasdesigned. The rupture disc is an important part of a gas gun and is used as a fast response valve whichburst at a predefined pressure. Afterdesign,it has been used instead of an electric valve to increase the maximum velocity that can be achieved by the gas gun. Toavoid fragmentation and to have a better control on rupture pressure,a groove isusuallygraved on the disc. Cross and circumferential grooves werestudied in this thesis. It was found that in most cases the discs with a cross groovewere not fully opened because they have four independent failure paths and these paths should be opened simultaneously. However, having...
Investigation of hydrodynamically dominated membrane rupture, using smoothed particle hydrodynamics–finite element method, Article Fluids ; Volume 4, Issue 3 , 2019 ; 23115521 (ISSN) ; Taeibi Rahni, M ; Akbarzadeh, A. M ; Javadi, K ; Ahmadi, G ; Sharif University of Technology
MDPI AG 2019
The rupturing process of a membrane, located between two fluids at the center of a three-dimensional channel, is numerically investigated. The smoothed particle hydrodynamics (SPH) and the finite element method (FEM) are used, respectively, for modeling the fluid and solid phases. A range of pressure differences and membrane thicknesses are studied and two different rupturing processes are identified. These processes differ in the time scale of the rupture, the location of the rupture initiation, the level of destruction and the driving mechanism. © 2019 by the authors
Article Iranian Journal of Science and Technology, Transaction B: Technology ; Volume 26, Issue 2 , 2002 , Pages 197-204 ; 03601307 (ISSN) ; Sharif University of Technology
Potassium chloride, as an osmotic agent and poly methacrylic acid, as a water-swelling additive have been incorporated in polydimethyl siloxane. By using caffeine as a model drug, the results of release experiments from two systems have been compared. Because of osmotic rupturing pseudo-zero-order release kinetics preceded by marked burst effect were observed. Since osmotic pressure of PMAA is higher than that of KCI, drug release rate from PMAA-PDMS matrices is higher than that from KCI-PDMS matrices. Since KCI is release along with the drug, but PMAA is not, therefore water-swelling additives may provide efficient drug release without releasing undesirable substances
Increasing the interfacial adhesion in poly(methyl methacrylate)/carbon fibre composites by laser surface treatment, Article Polymers and Polymer Composites ; Volume 14, Issue 6 , 2006 , Pages 585-589 ; 09673911 (ISSN) ; Mousavi, S. A. S ; Tilaki, R. M ; Frounchi, M ; Sharif University of Technology
Rapra Technology Ltd 2006
The impact strength of poly(methyl methacrylate)/caibon (long) fibre composites for denture prosthesis applications was improved by fibre surface treatment. The carbon fibre surfaces were modified by Nd:YAG laser irradiation at 1064 nm wavelength. Laser light intensity was adjusted at 100 mj per pulse that only changed the fibre surface roughness and did not lead to fibre rupture, as verified by scanning electron microscopy. Increased surface roughness of the fibres improved the adhesion of poly(methyl methacrylate) to the fibre surface. Adhesion between the fibres and poly(methyl methacrylate) was evaluated by a tear-off method and by scanning electron microscopy. The results also suggest...
M.Sc. Thesis Sharif University of Technology ; Maleki, Shervin
Since mid-twentieth century the shear lag phenomenon has attracted many scientists’ attention which led to a wide range of researches to be carried out on this topic and the results are considered in the design codes. In tension members in which all parts of the member in the vicinity of the connection are not connected, only some parts of the section contribute to load distribution and non-connected parts do not play any role in load transfer and this leads to non-uniform distribution of stress and stress concentration. This phenomenon is called shear lag which causes reduction of tensile strength of the member. The effect of this phenomenon is introduced as a reduction coefficient...
M.Sc. Thesis Sharif University of Technology ; Khalu, Alireza
The present paper discusses the possibility of adding recycled polymer fibres to high performance concrete (HPC). Fibres used in this study were recovered from discarded car timing belts. To investigate different characteristics of the concrete specimens several destructive and non-destructive tests, such as compressive strength, modulus of rupture, flexural toughness, ultrasonic velocity and electrical resistance tests were carried out. In addition, slump flow tests were conducted on the fresh concrete. Experimental results from the study showed that the use of low percentages (up to 0.5%) of waste fibres improved the modulus of rupture and flexural toughness. Based on ultrasonic and...
M.Sc. Thesis Sharif University of Technology ; Fallah, Famida
Tortuosity is an abnormality that may occur in some arteries, such as carotid. It can reduce the blood flow to distal organs, and even in severe cases, causes ischemia and stroke. Tortuosity can be congenital or occurs due to hypertension and reduced axial pre-stretch of artery, in which case called buckling. Since atherosclerotic plaques disrupt the normal pattern of blood flow, and thus make the artery more susceptible to buckling, in this study, the effect of atherosclerotic plaques on arterial stability has been investigated using computational simulation of fluid-structure interaction under pulsatile flow and large deformation. Ideal geometry of normal and atherosclerotic carotid artery...
Article Scientia Iranica ; Volume 17, Issue 2 B , 2010 , Pages 108-120 ; 10263098 (ISSN) ; Ziaei Rad, M ; Sharif University of Technology
The transient flow of a compressible gas generated in a pipeline after an accidental rupture is studied numerically. The numerical simulation is performed by solving the conservation equations of an axisymmetric, transient, viscous, subsonic flow in a circular pipe including the breakpoint. The numerical technique is a combined finite element-finite volume method applied on the unstructured grid. A modified K - ε model with a two-layer equation for the near wall region and compressibility correction is used to predict the turbulent viscosity. The results show that, for example, after a time period of 0.16 seconds, the pressure at a distance of 61.5 m upstream of the breakpoint reduces about...
M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davood
Liquid ammonia atmospheric tank (20000 ton) attached to Pardis Petrochemical Complex was ruptured on 8th August 2011 due to overpressure blast injury so that ammonia gas was spread throughout the complex. The current study was aimed to evaluate ammonia leakage and emission from the tank. For this purpose, in addition to evaluate ammonia emission into the air, pressure changes were investigated to simulate the rupture. First of all, ammonia tanks and urea stocks were simulated and then considering two aerial classes (D and B), the incident was stimulated. According to this model, up to 1000 m, was contaminated with 1000 ppm of ammonia. Since there was no experimental data for validating the...
M.Sc. Thesis Sharif University of Technology ; Fallah Ragabzadeh, Famida
Coronary arteries often experience tortuosity under internal blood pressure and longitude axial twisting. Arterial tortuosity can enhance the stress concentration on the artery walls. Now if the coronary arteries suffer from atherosclerosis (a common disease among adults) the stress concentration on the tortuous artery plaque will be enhanced as well. Increased stress on the plaque may result in plaque rupture and its consequent damages. This study aims to investigate the stress concentration on the plaques and blood flow patterns within the coronary arteries with plaque. Moreover, the plaque growth was predicted taking into account various geometrical parameters including fibrous cap...
M.Sc. Thesis Sharif University of Technology ; Maleki, Shervin
The purpose of the current study is to investigate the base metal capacity of stiffened seated angle connections and to inspect their behaviour. The effect of different parameters on the capacity of connections is examined, considering the damage in the column. This research is important since for welding design, codes require the designer to control the base metal capacity to check the connection capacity, while the method of calculating this capacity is not provided, and this issue is not considered in the design. In this research, ABAQUS finite element software was used to model and analyze the results. A total of 90 stiffened seated angle connections, which were connected to the flange...
The Effect of Heat Treatment on Microsructure, Hot Tensile Properties and Creep Bihavior of Nickel-based Superalloy CM88Y, M.Sc. Thesis Sharif University of Technology ; Asgari, Sirous
The Ni-base superalloy CM88Y has good hot corrosion resistance, high stability and strength at elevated temperature; accordingly, the alloy is used in manufacturing of gas turbine hot components. In most applications, heat treatment is required in order to achieve the desired mechanical properties and corrosion resistance of the working conditions; often three stages of heat treatment is designed for precipitation hardening nickel-base superalloy. In general, the effective parameters of heat treatment cycles includes temperature, time, heating rate and the cooling rate. In this study, the effect of cooling rate from partial solution temperature (second stage of heat treatment) on the...
Article Proceedings of the IASTED International Conference on Biomedical Engineering, BioMed 2014 ; 2014 , pp. 239-243 ; Mehboudi, N ; Abdollahi, M ; Shamloo, A ; Naghdabadi, R ; Sharif University of Technology
The main goal of this study is to investigate the effects of plaque structure on its stress distribution. Rupture of plaque causes cerebrovascular diseases which lead to high mortality rates all over the world. Computers are powerful tools to understand the mechanism of plaque rupture. In this study, 3D fluid structure interaction simulation is constructed in ABAQUS 6.13 to clarify the relation between stress distribution of plaque and its structure. A model of common carotid artery with distributed stenosis was chosen for the simulation. To investigate the effects of plaque structure on stress distribution, thickness of fibrous cap and lipid core size were varied in the stenosis....
Article Materials Science and Technology (United Kingdom) ; Vol. 30, issue. 1 , January , 2014 , p. 109-115 ; Ekrami, A ; Kokabi, A. H ; Sharif University Of Technology
The time required to ensure completion of the isothermal solidification process is the key in obtaining an intermetallic free and robust joint after diffusion brazing. In view of economic considerations, it is interesting to perform bonding process trials using standard heat treatment cycles. This paper addresses the effect of applying the standard heat treatment cycle including homogenisation, solution and double aging treatments on the microstructural and mechanical response of diffusion brazed IN718. A commercial Ni-7Cr-4·5Si- 3?2B-3Fe (wt-%) brazing alloy was used as the interlayer. Results showed that bonds made with the standard homogenisation treatment, at 1100°C, exhibited a eutectic...
Effects of pozzolans together with steel and polypropylene fibers on mechanical properties of RCC pavements, Article Construction and Building Materials ; Volume 26, Issue 1 , January , 2012 , Pages 102-112 ; 09500618 (ISSN) ; Azizkhani, R ; Torki Harchegani, M. E ; Sharif University of Technology
Effects of pozzolans and fibers on mechanical properties of RCC are addressed. The mechanical properties were evaluated using optimum moisture with different amounts of pozzolans, steel and polypropylene fibers. Using pozzolans, maximum increase in compressive strength was observed to occur between 28 and 90 days of age, rupture modulus was found to decrease; but toughness indices did not change considerably. The influence of steel fibers on compressive strength was often more significant than that of PP fibers; but neither steel nor PP fibers did contribute to increase in the rupture modulus independently from pozzolans. Also, the toughness indices increased when steel fibers were used
Effect of processing parameters on electrical, mechanical and magnetic properties of iron-resin soft magnetic composite, Article Powder Metallurgy ; Volume 50, Issue 1 , 2007 , Pages 86-90 ; 00325899 (ISSN) ; Madaah Hosseini, H. R ; Miraghaei, S ; Sharif University of Technology
In the present paper, a practical thermal treatment process has been introduced to stress relieve the iron powders in a soft magnetic composite. The composites were pressed and treated at different pressures and temperatures. Also, some of the samples were treated for various periods of time at 200°C. Density, electrical resistivity and transverse rupture strength of the samples were measured and fracture surfaces were studied by SEM. A series of tests were performed to determine the DC magnetic properties of the samples. It has been shown that there are optimum amounts of resin content and compaction pressure and temperature, rather than time is the dominant factor in stress relief of the...
Microstructure and mechanical properties of WC-10Co cemented carbide containing VC or (Ta, Nb)C and fracture toughness evaluation using different models, Article International Journal of Refractory Metals and Hard Materials ; Volume 31 , 2012 , Pages 141-146 ; 02634368 (ISSN) ; Abachi, P ; Simchi, A ; Sharif University of Technology
This article describes a study on WC-10Co cemented carbides with different percent of grain growth inhibitors. Samples were prepared by the conventional powder metallurgy method, using WC and Co powder and different concentrations of VC and (Ta, Nb)C powder. All samples were processed using a hot isostatic press (HIP) and the effect of grain growth inhibitors on the microstructure and mechanical properties were investigated. Additionally, microstructure and powder particle morphology were examined using scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS). The specimen's microstructure proved that the addition of VC is more effective at suppressing grain growth than...
Silver nanoparticles within vertically aligned multi-wall carbon nanotubes with open tips for antibacterial purposes, Article Journal of Materials Chemistry ; Volume 21, Issue 2 , Oct , 2011 , Pages 387-393 ; 09599428 (ISSN) ; Abdolahad, M ; Abdi, Y ; Mohajerzadeh, S ; Sharif University of Technology
Vertically aligned multi-wall carbon nanotube (CNT) arrays were fabricated in tip-growth mode on Ni/Si substrates using plasma enhanced chemical vapor deposition. In a purification process including hydrogenation and acid washing of the Ni/CNTs, the oxygen-containing functional groups were substantially reduced and a wide hollow core at the tip of the CNTs was formed by removing the Ni seeds. Sol-gel silver nanoparticles were deposited on the surface of the unpurified Ni/CNTs, while they could also be embedded within the hollow core of the Ni-removed CNTs. The persistency of the silver ions in the Ni-removed Ag-CNTs in comparison to the release of the silver ions from the Ag-Ni/CNTs in a...