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Search Results: 1 - 10 of 47371 matches for " failure analysis "
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Design of a Cantilever - Type Rotating Bending Fatigue Testing Machine  [PDF]
K. K. Alaneme
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.1011078
Abstract: This research is centered on the design of a low–cost cantilever loading rotating bending fatigue testing machine using locally sourced materials. The design principle was based on the adaptation of the technical theory of bending of elastic beams. Design drawings were produced and components/materials selections were based on functionality, durability, cost and local availability. The major parts of the machine: the machine main frame, the rotating shaft, the bearing and the bearing housing, the specimen clamping system, pulleys, speed counter, electric motor, and dead weights; were fabricated and then assembled following the design specifications. The machine performance was evaluated using test specimens which were machined in conformity with standard procedures. It was observed that the machine has the potentials of generating reliable bending stress – number of cycles data; and the cost of design (171,000 Naira) was lower in comparison to that of rotating bending machines from abroad. Also the machine has the advantages of ease of operation and maintenance, and is safe for use.
Modeling and Numerical Simulations with Compressible Damaged Hyperelastic Law: Application to the Laminated Rubber Bearing  [PDF]
Maha Zaghdoudi, Zohra Gaiech, Lamia Bejaoui, Zoubeir Tourki, Adnane Boukamel
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.311119
Abstract: Hyperelastic model with damage induced compressibility is implemented in the ABAQUS software using the subrou- tine Umat. A thermodynamic model is proposed taking into account the nonlinearity of the material behavior. Within the present work, the behavior of laminated rubber bearing structure is studied for two geometrical sets of materials (A-type and equivalent material) under complex monotonic loading conditions. A new geometric edge of laminated rubber bearing is proposed in order to reduce the development costs of the structure. The proposed model allowed finding a good homogenized damage distribution for the same overall stiffness.
Recognition and Analysis of Corrosion Failure Mechanisms
Steven Suess
Journal of Systemics, Cybernetics and Informatics , 2006,
Abstract: Corrosion has a vast impact on the global and domestic economy, and currently incurs losses of nearly $300 billion annually to the U.S. economy alone. Because of the huge impact of corrosion, it is imperative to have a systematic approach to recognizing and mitigating corrosion problems as soon as possible after they become apparent. A proper failure analysis includes collection of pertinent background data and service history, followed by visual inspection, photographic documentation, material evaluation, data review and conclusion procurement. In analyzing corrosion failures, one must recognize the wide range of common corrosion mechanisms. The features of any corrosion failure give strong clues as to the most likely cause of the corrosion. This article details a proven approach to properly determining the root cause of a failure, and includes pictographic illustrations of the most common corrosion mechanisms, including general corrosion, pitting, galvanic corrosion, dealloying, crevice corrosion, microbiologically-influenced corrosion (MIC), corrosion fatigue, stress corrosion cracking (SCC), intergranular corrosion, fretting, erosion corrosion and hydrogen damage.
Assessment and Risk Management of Potential Hazards by Failure Modes and Effect Analysis (FMEA) Method in Yazd Steel Complex  [PDF]
Mehrzad Ebrahemzadih, G. H. Halvani, Behzad Shahmoradi, Omid Giahi
Open Journal of Safety Science and Technology (OJSST) , 2014, DOI: 10.4236/ojsst.2014.43014
Abstract: Background: Failure mode and effect analysis (FMEA) is a widely used quality improvement and risk assessment tool in manufacturing. The aim of this study is to assess potential hazards by failure modes and effect analysis (FMEA) method in Yazd Steel Complex. Methods: In this descriptive study, we evaluated the risks in different parts of the complex by using FMEA method and by using FMEA Worksheets (PFMEA) derived from the standard (MIL_STD-882). Failure modes and the various components and effects as using quantitative score to the risk priority (RPN) were obtained. PFMEA worksheets were completed and, we reevaluated the weaknesses part of the system. Activities related to each from the different parts of Yazd Steel Complex by using the scores risk priority (RPN) were evaluated. Then the results obtained by using SPSS software were performed by evaluation and analysis. Results: The findings showed that the steel maker lime unite and steel making ingot casting achieved the highest of RPN before and after corrective actions measures (490, 168) and environmental health unite and roll styles unite achieved the lowest of RPN before and after corrective actions measures (28, 20). Conclusions: The results show that the FMEA technique can identify a higher number of hazards than any other technique. The important point is that selection of an appropriate technique plays an important role in identifying a higher number of hazards.
Design and Performance Evaluation of a Sustained Load Dual Grip Creep Testing Machine  [PDF]
Kenneth Kanayo Alaneme, Bethel Jeremiah Bamike, Godwin Omlenyi
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2014, DOI: 10.4236/jmmce.2014.26054
Abstract: The design and performance evaluation of a sustained load creep testing machine was undertaken in this research. The design was motivated by the need to make locally available, a cost effective, technically efficient, and easily operated creep testing facility; for creep behaviour studies of materials. Design drawings and purchase of materials and components for the design were undertaken after thorough evaluation of the following design and materials selection criteria: design principle and theory, local availability of raw materials and components required for the design, material properties, cost of materials and design, ease of utilization and maintenance, and basis of testing and data capture. The machine casing and frame, heating chamber (consisting of the furnace and a dual specimen mounting stage), load lever and hanger system, and the electro-technical components; were fabricated and coupled following the produced design specifications. The machine was tested and its performance was assessed using its heating efficiency, repeatability and reproducibity of experimental test results, maintainability and cost-effectiveness as criteria. It was observed from repeat tests that the machine has the capacity of generating reliable data for computing creep strain-time results. The efficiency and temperature regulating capacity of the heating unit of the machine were also observed to be very satisfactory. The cost of the design was about 112,000 Naira ($700.00) which is cheaper in comparison to similar commercial creep testing machines from abroad. The machine was also found not to pose maintenance or repairs challenges.
Progressive Analysis of Bearing Failure in Pin-Loaded Composite Laminates Using an Elasto-Plastic Damage Model  [PDF]
Kang Xue
Materials Sciences and Applications (MSA) , 2018, DOI: 10.4236/msa.2018.97042
Abstract: Bearing failure of composite laminate is very complicated due to the complexity of different failure mechanisms and their interactions. In this paper, an elasto-plastic damage model is built up to describe the process of failure in composite laminates subjected to bearing load. Non-linear behavior of composite before failure is taken into consideration by using a modified Sun-Chen one parameter plasticity model. LaRC05 failure criteria are employed to predict the initiation of failure and the evolution of failure is described by a CDM based stiffness degradation model. Both theory and some application issues like parameter determination are discussed according to phenomenon of experiments. The model is firstly validated by several experiment results of unidirectional laminate and then applicated into the progressive analysis of bearing failure in pin-loaded multidirectional laminates, both intralaminar and interlaminar damage are taken into consideration. The result of finite element analysis is compared with experiment results; it shows good agreements in both mechanical response and progress of failure, so the model can be evaluated to be effective and practical in bearing failure analysis of composite laminates.
Analysis of Influencing Factors on Survival Time of Patients with Heart Failure  [PDF]
Jianwei Sheng, Xiyuan Qian, Tong Ruan
Open Journal of Statistics (OJS) , 2018, DOI: 10.4236/ojs.2018.84042
Abstract: To explore the influencing factors of survival time of patients with heart failure, a total of 1789 patients with heart failure were collected from Shanghai Shuguang Hospital. The Cox proportional hazards model and the mixed effects Cox model were used to analyze the factors on survival time of patients. The results of Cox proportional hazards model showed that age (RR = 1.32), hypertension (RR = 0.67), ARB (RR = 0.55), diuretic (RR = 1.48) and antiplatelet (RR = 0.53) have significant impacts on the survival time of patients. The results of mixed effects Cox model showed that age (RR = 1.16), hypertension (RR = 0.61), lung infection (RR = 1.43), ARB (RR = 0.64), β-blockers (RR = 0.77) and antiplatelet (RR = 0.69) have a significant impact on the survival time of patients. The results are consistent with the covariates age, hypertension, ARB and antiplatelet but inconsistent with the covariates lung infection and β-blockers.
Análise de falha em isolador polimérico
Lisboa, M.B.;Furtado, H.C.;Oliveira, W.P.;
Matéria (Rio de Janeiro) , 2011, DOI: 10.1590/S1517-70762011000400002
Abstract: the objective of this study was to determine the cause of the failure in service of a polymeric insulator used in a 138 kv transmission line (tl). the study was conducted following the most usual recommended methodology for failure analysis, metallurgical characterization and chemicals tests. the tests identified that the mechanism of stress corrosion cracking (scc) was responsible for the insulator′s brittle fracture. this mechanism is often associated with the existence of flaws in polymeric insulators compounds (epoxy resins reinforced with boron rich glass fibers) in the presence of moisture. the tests revealed that the design characteristics of the insulator were inappropriate because they allowed the penetration of moisture into its lower termination and subsequent contact with the grp (glass reinforced polymer) core, leading to its disruption. these results led to the replacement of all insulators with similar characteristics by the electric power transmission utility.
O objeto em causa na cura
Hoffmann, Christian;
ágora: Estudos em Teoria Psicanalítica , 2008, DOI: 10.1590/S1516-14982008000200001
Abstract: the object involved in the treatment. repetition is tantamount to loss, and therefore of jouissance's failure. from that failure the object of wish can be deduced. analytic therapy aims at bringing about that object as the cause of the wish.
Finite Element Analysis of Graphite/Epoxy Composite Pressure Vessel  [PDF]
Meng-Kao Yeh, Tai-Hung Liu
Journal of Materials Science and Chemical Engineering (MSCE) , 2017, DOI: 10.4236/msce.2017.57003
Shell structure is widely used in industrial applications, such as in machinery, aerospace, ship and building fields, as well as containers of pressurized chemicals or liquefied natural gas. Graphite/epoxy composites has advantages of light weight, high strength, corrosion resistance, low expansion, low shrin kage and are often used in the form of composite pressure vessel for various engineering applications. In this study, the stress distributions of composite pressure vessel were analyzed. The finite element code ANSYS was used in analysis, in which the eight-node element SHELL 281 was adopted. The internal pressure 20 MPa, as in container of compressed natural gas, was applied inside the symmetrical cross-ply graphite/epoxy composite pressure vessel. The finite element model was established with suitable mesh size and boundary conditions. The stress distributions are discussed for the composite pressure vessel, especially for the inner two layers at the junction of semis pherical part. The Tsai-Hill criterion was used to assess the failure of composite pressure vessel.
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