Loading...
Search for:
failure
0.008 seconds
Total 555 records
A failure analysis study on the fractured connecting bolts of a filter press
, Article Case Studies in Engineering Failure Analysis ; Volume 4 , 2015 , Pages 26-38 ; 22132902 (ISSN) ; Alizadeh, R ; Attarian, M ; Jaferian, Y ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
The purpose of this study was to investigate the main causes of the co-fracture of sixteen connecting bolts of a filter press cylinder-piston system. Stress state of the bolts during the service conditions has been analyzed and the failure reasons were determined from the fractography analysis and gathered information. According to the obtained results, it was concluded that the bolts had failed by the fatigue mechanism. It seems that insufficient torque was used during assembly
Microstructural evaluation and fracture mechanisms of failed IN-738LC gas turbine blades
, Article Case Studies in Engineering Failure Analysis ; Volume 1, Issue 2 , April , 2013 , Pages 85-94 ; 22132902 (ISSN) ; Khoshmanesh, R ; Nategh, S ; Davami, P ; Sharif University of Technology
2013
Prediction of the failure mode of automotive steels resistance spot welds
, Article Science and Technology of Welding and Joining ; Volume 25, Issue 6 , 2020 , Pages 511-517 ; Jaderian, S ; Mazaheri, Y ; Pouranvari, M ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
In this study, the critical nugget size, at which the failure state in tensile shear test changed from the interfacial failure mode to the pull-out failure one, was estimated as a function of nugget and base metal hardness. The proposed approach could address the effect of various parameters involved in resistance spot welding process, such as sheet thickness, base metal chemical composition and physical properties of electrodes and sheets. The reliability of the present model was evaluated using independent experimental results. Based on the obtained results, the effect of steel composition on critical nugget diameter was found to be more important, especially for the sheets thicker than...
Wear-out failure of a power electronic converter under inversion and rectification modes
, Article 11th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2019, 29 September 2019 through 3 October 2019 ; 2019 , Pages 1598-1604 ; 9781728103952 (ISBN) ; Davari, P ; Zhou, D ; F-Firuzabad, M ; Blaabjerg, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
The expected lifetime of a power electronic converter is limited by its fragile components such as semiconductor devices and capacitors. These components are prone to wear-out failures depending on the converter mission profile and component thermal characteristics. This paper explores the wear-out failure of the power converter semiconductor devices in inverting and rectifying modes of the converter using different power factors. The obtained results show the different wear-out characteristics of a converter under rectification, inversion, and also partial-inversion/rectification modes as well as when provides reactive power support. Moreover, this paper proposes B10 lifetime curves to...
A Micromechanical Progressive Damage Algorithm for Prediction of Failure in Composite Laminates
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkheili, Ali (Supervisor)
Abstract
Macro models which are used to predict failure of composite structures in most cases predict ¬reasonable results; however, they are not able to consider micro level parameters such as micro cracks. Furthermore, these failure macro models need various empirical data. Considering micromechanical construction of composites; including fiber, matrix and their interfaces, using micromechanical models for predicting failures in these phases is more appropriate. The aim of this study is to represent a micro-mechanical algorithm in order to predict progressive failures of fiber-reinforced composites. The failure model which is used in this study is a micromechanical modeling of failure (MMF) model,...
Peak load and energy absorption of DP600 advanced steel resistance spot welds
, Article Ironmaking and Steelmaking ; Volume 44, Issue 9 , 2017 , Pages 699-706 ; 03019233 (ISSN) ; Pouranvari, M ; Salim, R. K ; Hashim, F. A ; Marashi, S. P. H ; Sharif University of Technology
Abstract
The paper aims at investigating the microstructure, failure mode transition, peak load and energy absorption of DP600 dual phase steel during the tensile-shear test. It was found that the welding current has profound effect on the load–displacement characteristics. In the low welding current, welds failed in interfacial failure mode. Increasing welding current resulted in sufficient weld nugget growth to promote double-sided pullout failure mode with improved mechanical properties. Further increase in the welding current caused expulsion and failure mode was changed to single-sided pullout with reduced energy absorption capability. It was found that the fusion zone size is the key parameter...
Reliability evaluation in microgrids with non-exponential failure rates of power units
, Article IEEE Systems Journal ; Volume 14, Issue 2 , 2020 , Pages 2861-2872 ; Fotuhi Firuzabad, M ; Blaabjerg, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
This article explores the impacts of non-exponentially distributed failures on reliability of microgrids. Failure rate of some components such as power electronic converters is not constant, while they play a major role in microgrids. Consequently, their failure characteristics will affect the microgrid reliability. Hence, the conventional reliability evaluation approaches based on mean time to failure may introduce inaccurate inputs for decision making in planning and operation of microgrids. In this article, different approaches are employed for evaluating the reliability of microgrids with non-constant failure rates. The obtained results indicate that the system reliability remarkably...
A transient fully coupled thermo-poroelastic finite element analysis of wellbore stability
, Article Arabian Journal of Geosciences ; Volume 8, Issue 6 , 2014 , Pages 3855-3865 ; ISSN: 18667511 ; Goodarznia, I ; Shadizadeh, S. R ; Sharif University of Technology
Abstract
Stress variations around wellbores and in the reservoirs are of much interest in subsequent drilling operations, future production, and petroleum reservoir development. Stress variations induced by in situ stresses, pore pressure, and temperature changes during drilling operations may lead to various modes of instabilities in forms of induced fractures and borehole breakouts. Previous studies of thermally induced stresses were primarily based on either assumptions of heat conduction through rock matrix or heat convection, in this case, without considering the effect of solid grain thermal conductivity. To analyze wellbore stability, in the present work, a thermo-poro-mechanical model that is...
Failure analysis of a first stage gas turbine blade
, Article Engineering Failure Analysis ; 2010 ; 13506307 (ISSN) ; Abouali, S ; Akbari Garakani, MFailure analysis of a repaired gas turbine nozzle
, Article Engineering Failure Analysis ; 13506307 (ISSN) ; Abouali, S ; Akbari Garakani, M ; Sharif University of TechnologyFailure procedure in epoxy adhesive joining composite plates
, Article Iranian Journal of Science and Technology - Transactions of Mechanical Engineering ; 2020 ; Kadivar, M. H ; Zohoor, H ; Farid, M ; Hematiyan, M. R ; Sharif University of Technology
Springer
2020
Abstract
In this paper, several numerical simulations are performed to study the failure of epoxy adhesive joining composite plates. Different geometries for the joint and its edge are considered, and the effects of these geometries on the failure load are investigated. Moreover, the joints are subjected to different types of loading in order to determine the failure load. The failure theories of composite materials are implemented into the finite element software ABAQUS, and the failure propagation in the joint is studied. © 2020, Shiraz University
Experimental study of rolling element bearing failure pattern based on vibration growth process
, Article Proceedings of the 29th European Safety and Reliability Conference, ESREL 2019, 22 September 2019 through 26 September 2019 ; 2020 , Pages 1179-1186 ; Behzad, M ; Ghodrati, B ; Taghizadeh Vahed, A ; Sharif University of Technology
Research Publishing Services
2020
Abstract
Rolling-element bearing (REB) Failure is one of the most common failure in rotary machines in industry. Therefore, this concern draws attention to the concept of diagnostic and the prediction of REB failure. The efficacy of vibration analysis in this area has led many researchers to focus on this topic in recent decades. Defective bearings such as fatigue, surface roughness, and corrosion can lead to disastrous accidents. Therefore, providing an algorithm for the detection and classification of bearing defects is valuable and useful. The prediction of the bearing's lifetime is important to ensure the planned production in an industrial unit. In this paper, different models for performance...
Analysis of system failure in a CNG site
, Article Renewable Energy and Power Quality Journal ; Volume 1, Issue 5 , 2007 , Pages 472-476 ; 2172038X (ISSN) ; Kharradmehr, H ; Roushan Milani, K ; Mokhtari, H ; Sharif University of Technology
European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ)
2007
Abstract
This paper presents the results of a thorough power quality analysis in order to determine the cause of failure in a Compressed Natural Gas (CNG) distribution transformer. The paper presents the field data and determines power quality indices of such loads based on IEEE/IEC standards. It provides steady state time-series parameters as well as transient waveforms. Different signatures of the voltage and current signals are extracted, and consequences of the distortions are described. The analysis is clarified by presenting both time domain captured waveforms and statistical power quality indices. Optimum solution for improving power quality and prevent component failure is also proposed. ©...
Exploring stakeholders and their requirements in the process of home hemodialysis: A literature review
, Article Seminars in Dialysis ; 2021 ; 08940959 (ISSN) ; Pintelon, L ; Martin, H ; Khan, R. A ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
Providing home hemodialysis (HHD) therapy is a complex process that not only requires the use of a complex technology but also involves a diverse group of stakeholders, and each stakeholder has their requirements and may not share a common interest. Bringing them together will require the alignment of their interests. A process management perspective can help to accomplish the alignment of their interests. To align their interests, it is crucial to identify interest groups and understand their interests. The main objective of this paper is to identify the stakeholders and represents their interests as a list of requirements in the HHD process. An extensive literature review has been carried...
A particular criterion for progressive failure analysis of carbon/phenolic tape-wounded conic shells
, Article International Journal of Damage Mechanics ; Volume 30, Issue 8 , 2021 , Pages 1238-1260 ; 10567895 (ISSN) ; Karimian, M ; Jafari, H. R ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
Conic shell structures are widely used in aerospace industries. In the literature various models have been proposed to failure analysis of composite materials. Clearly, each model has a favorable range of applications. In this paper tensile, compressive, shear and thermal expansion properties of tape-wounded Carbon/Phenolic composites are firstly measured at various temperatures in range 23–200°C. The captured properties are then taken into account to progressive failure analysis of a conic Carbon/Phenolic structure under internal pressure and thermal loadings. For this end, a particular failure criterion is proposed to predict failure in the composite structures with a reasonable margin of...
Effect of strain rate on tensile properties of sheep disc anulus fibrosus
, Article Technology and Health Care ; Volume 12, Issue 4 , 2004 , Pages 333-342 ; 09287329 (ISSN) ; Parnianpour, M ; Shirazi Adl, A ; Wang, J. L ; Grynpas, M. D ; Sharif University of Technology
IOS Press
2004
Abstract
We investigated the effect of loading rate on tensile properties of sheep bone-anulus-bone specimens in axial direction. Disc anulus Samples with adjacent bone attachments were prepared from lateral, posterior and anterior regions of sheep lumbar spinal segments. The specimens were then tested at different strain rates under non-destructive cyclic tensile loading followed by destructive tensile loading. Each specimen was prepared by embedding the bony parts in the polymethylmetacrylate (PMMA) exposing the anulus portion to support tension. The results of non-destructive cyclic tests indicated a decrease in the hysteresis energy loss as strain rate increased. In the destructive tests, no...
Application of a failure analysis to powder forming processes
, Article Journal of Materials Processing Technology ; Volume 143-144, Issue 1 , 2003 , Pages 46-51 ; 09240136 (ISSN) ; Sharif University of Technology
2003
Abstract
In this paper, an h-adaptive analysis for the mixed finite element solution of powder forming problems is presented involving localization due to material instability. A remeshing strategy is employed to compute the distribution of required element size using the estimated error distribution. Once the new element size and its alignment have been indicated, an automated procedure is used to construct the mesh according to a predetermined size and elongation distribution. The numerical results were obtained for a multi-level component to indicate the failure surfaces and evaluate the ultimate capacity of material. © 2003 Elsevier Science B.V. All rights reserved
Study the failure of casted copper anode: The formation of bumps defects on the surface of the anode during casting
, Article Engineering Failure Analysis ; Volume 138 , 2022 ; 13506307 (ISSN) ; Reza Khayati, G ; Javad Khorasani, S. M ; Assadat Yaghubi, N ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Copper anode (∼98%) is widely used to produce the cathode (99.995 wt%) in electrorefining process. These anodes sometimes become problematic from the production line due to the presence of bumps/holes on their surface. To find the reason of this defect, chemical composition of the three casted anodes was determined by the quantmeter analysis. Also, the microscopic and phase analysis were done by FESEM, EDS, XRD, and XRF for three types of anodes bump. The chemical analysis of anodes confirmed a high level of sulfur and oxygen, which have a key role in the formation of bumps. The results confirmed the presence of impurities including Cu2S, BaSO4, CaCO3 and MgCO3, which cause the formation of...
A study of the reliability of various types of the electric vehicles
, Article 2012 IEEE International Electric Vehicle Conference, IEVC 2012 ; 2012 ; 9781467315623 (ISBN) ; Ghahnavieh, A. R ; Mobarakeh, A. S
2012
Abstract
The reliability Studies are done in order to determine the probability of functioning or availability of different engineering systems. These studies can also provide a basis for comparing different structures of a system and can be used as a tool to improve the system design. Also, reliability is an important consideration in the planning, design and operation of transit system. Since the issue of the reliability of electric vehicles has not been sufficiently and seriously evaluated yet, so in this paper, the reliability of the various types of these kinds of vehicles will be discussed and then the reliability indices of them will be compared with each other and with the conventional cars
Determination of active pressure exerted on retaining walls with a circular failure wedge using the horizontal slices method in cohesive-frictional soil
, Article Journal of Engineering and Applied Sciences ; Volume 12, Issue 19 , 2017 , Pages 5012-5017 ; 1816949X (ISSN) ; Faghirizadeh, M. K ; Hosseini, S ; Naghibi, M ; Sharif University of Technology
Medwell Journals
2017
Abstract
The current study used the horizontal slices method to develop a new formulation to calculate active pressure on retaining walls. In this method, the failure wedge is assumed to be circular in cohesive-frictional soil. In addition to the formula, graphs are provided to determine the center and radius of failure without need for calculation to determine the pressure exerted on the retaining wall. A comparison of the results of the proposed method with previous methods shows that the active pressure calculated using a circular failure wedge was higher than when using a plate failure wedge; confirming the importance of the circular failure wedge. The proposed method can calculate the shear...