scholarly journals Precursors of Catastrophic Failures

2005 ◽  
pp. 293-310
Author(s):  
Srutarshi Pradhan ◽  
Bikas K. Chakrabarti
Keyword(s):  
Catastrophic Failures

The Effect of Secondary Metalworking Processes on Susceptibility of Aircraft to Catastrophic Failures and Prevention Methods

2013 ◽  
Vol 58 (4) ◽  
pp. 1207-1212
Author(s):  
E.S. Dzidowski
Keyword(s):  
Dynamic Recovery ◽  
Fatigue Cracks ◽  
Shear Bands ◽  
Adiabatic Shear ◽  
Deformation Mechanisms ◽  
Processing Maps ◽  
Adiabatic Shear Bands ◽  
Flow Localization ◽  
Catastrophic Failures ◽  
Prevention Methods

Abstract The causes of plane crashes, stemming from the subcritical growth of fatigue cracks, are examined. It is found that the crashes occurred mainly because of the negligence of the defects arising in the course of secondary metalworking processes. It is shown that it is possible to prevent such damage, i.e. voids, wedge cracks, grain boundary cracks, adiabatic shear bands and flow localization, through the use of processing maps indicating the ranges in which the above defects arise and the ranges in which safe deformation mechanisms, such as deformation in dynamic recrystallization conditions, superplasticity, globularization and dynamic recovery, occur. Thanks to the use of such maps the processes can be optimized by selecting proper deformation rates and forming temperatures.

Rapid Restoration Sequence of Fiber Links and Communication Paths from Catastrophic Failures

2016 ◽  
Vol E99.A (8) ◽  
pp. 1510-1517 ◽  
Author(s):  
Akihiro KADOHATA ◽  
Takafumi TANAKA ◽  
Wataru IMAJUKU ◽  
Fumikazu INUZUKA ◽  
Atsushi WATANABE
Keyword(s):  
Catastrophic Failures ◽  
Rapid Restoration ◽  
Fiber Links ◽  
Communication Paths

scholarly journals A Brief Insight into Microbial Corrosion and its Mitigation with Eco-friendly Inhibitors

2021 ◽  
Vol 7 (3) ◽  
Author(s):  
M. Lavanya
Keyword(s):  
Electrochemical Impedance ◽  
Wide Spectrum ◽  
Present Review ◽  
Electrochemical Reactions ◽  
Microbial Corrosion ◽  
Engineering Applications ◽  
Microbially Influenced Corrosion ◽  
Catastrophic Failures ◽  
Chemical Strategies ◽  
Insight Into

AbstractCorrosion results from the electrochemical reactions between the metal and its existing environment. Corrosion results in severe and expensive damage to a wide spectrum of industries. When microbes are involved in corrosion it is seldom possible to economically evaluate its impact. Microbially influenced corrosion is recognized to cause catastrophic failures contributing to approximately 20% of the annual losses. In many engineering applications, microbially influenced corrosion control is of prime importance. Expensive, toxicity and sometimes, even ineffectiveness of the current chemical strategies to mitigate microbially influenced corrosion have shifted the interest towards eco-friendly inhibitors. The present review discusses microbial induced corrosion in various metals and its inhibition through eco-friendly inhibitors. In addition, the study also reviews the morphological and electrochemical impedance results.

scholarly journals A Review of Techniques for RSS-Based Radiometric Partial Discharge Localization

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 909
Author(s):  
David W. Upton ◽  
Keyur K. Mistry ◽  
Peter J. Mather ◽  
Zaharias D. Zaharis ◽  
Robert C. Atkinson ◽  
...  
Keyword(s):  
Power Systems ◽  
High Voltage ◽  
Partial Discharge ◽  
Specific Area ◽  
Electrical Insulation ◽  
Acoustic Detection ◽  
Advantages And Disadvantages ◽  
Initial Stage ◽  
Catastrophic Failures ◽  
Radiometric Detection

The lifespan assessment and maintenance planning of high-voltage power systems requires condition monitoring of all the operational equipment in a specific area. Electrical insulation of electrical apparatuses is prone to failure due to high electrical stresses, and thus it is a critical aspect that needs to be monitored. The ageing process of the electrical insulation in high voltage equipment may accelerate due to the occurrence of partial discharge (PD) that may in turn lead to catastrophic failures if the related defects are left untreated at an initial stage. Therefore, there is a requirement to monitor the PD levels so that an unexpected breakdown of high-voltage equipment is avoided. There are several ways of detecting PD, such as acoustic detection, optical detection, chemical detection, and radiometric detection. This paper focuses on reviewing techniques based on radiometric detection of PD, and more specifically, using received signal strength (RSS) for the localization of faults. This paper explores the advantages and disadvantages of radiometric techniques and presents an overview of a radiometric PD detection technique that uses a transistor reset integrator (TRI)-based wireless sensor network (WSN).

scholarly journals Temperature Distribution in the Insulation System of Condenser-Type HV Bushing—Its Effect on Dielectric Response in the Frequency Domain

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4016
Author(s):  
Krzysztof Walczak ◽  
Jaroslaw Gielniak
Keyword(s):  
Temperature Distribution ◽  
Working Conditions ◽  
Dielectric Response ◽  
Power Transformers ◽  
Response Analysis ◽  
Insulation System ◽  
Large Power ◽  
Catastrophic Failures ◽  
Significant Temperature ◽  
Specific Construction

HV bushings are an important part of the equipment of large power transformers, responsible for their many serious (including catastrophic) failures. Their proper exploitation needs to apply correct and reliable diagnostics, e.g., the use of dielectric response methods, that take into account their specific construction and working conditions. In this article, based on laboratory tests carried out on a real bushing, it has been shown that the significant temperature distribution within its core significantly affects the shape of the dielectric response of its insulation; therefore, the approach to its modeling should be changed. Hence, a new method for interpreting the results, using the so-called the 2XY model, is proposed. Subsequently, based on the measurements made on the insulators in operation, a new modeling method was verified. In conclusion, it can be stated that the 2XY model significantly improves the reliability of the dielectric response analysis, which should be confirmed in the future by tests on withdrawn and revised insulators.

scholarly journals Catastrophic Failures Propagate Field of Fracture Mechanics

MRS Bulletin ◽  
1995 ◽  
Vol 20 (8) ◽  
pp. 74-75 ◽  
Author(s):  
Robin L. Blumberg Selinger
Keyword(s):  
Fracture Mechanics ◽  
Catastrophic Failures

FINDING OF MICRODAMAGE MORPHOLOGY DIFFERENCES IN MOUSE FEMORAL BONES WITH DISTINCT MINERALIZATION LEVELS

2011 ◽  
Vol 11 (02) ◽  
pp. 423-432 ◽  
Author(s):  
X. NEIL DONG ◽  
HUIJIE LENG ◽  
QITAO RAN ◽  
XIAODU WANG
Keyword(s):  
Failure Analysis ◽  
Numerical Study ◽  
Staining Technique ◽  
Pathological Changes ◽  
Basic Fuchsin ◽  
Four Point Bending ◽  
Microdamage Accumulation ◽  
Catastrophic Failures ◽  
Bone Ultrastructure ◽  
Probabilistic Failure Analysis

Microdamage progression in bone is dependent on the ultrastructure of the tissue. Thus, any pathological changes in bone ultrastructure may be reflected in the pattern and capacity of microdamage accumulation. A previous numerical study of microdamage progression in bone using a probabilistic failure analysis approach predicts that the microdamage morphology (either linear microcracks or diffuse damage) is very sensitive to the level of mineralization in bone, which is also implicated in some experimental observations. To examine the prediction, femurs from two strains of mice (C57BL/6J, N = 10 and C3H/HeJ, N = 11) that have distinct mineralization levels were fatigued under four-point bending to create damage in the bone tissues. After testing, the microdamage morphology of the bone samples was examined using bulk-staining technique with basic fuchsin. The results demonstrate that more linear microcracks are observed in femurs of C3H/HeJ (higher mineralization), whereas more diffuse-like damage is found in C57BL/6J femurs (less mineralized). Compared with linear microcracks, the formation of diffuse damage tends to dissipate more energy and help bone to avoid catastrophic failures. Therefore, results from this study may help explain why highly mineralized bone tends to be more brittle. Observations from this study are consistent with the numerical prediction from the previous study, suggesting that mineralization has a significant effect on the microdamage morphology of bone.

scholarly journals Effect of post type and restorative techniques on the strain and fracture resistance of flared incisor roots

2011 ◽  
Vol 22 (3) ◽  
pp. 230-237 ◽  
Author(s):  
Gisele Rodrigues da Silva ◽  
Paulo César de Freitas Santos-Filho ◽  
Paulo Cézar Simamoto-Júnior ◽  
Luis Roberto Marcondes Martins ◽  
Adérito Soares da Mota ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Fracture Resistance ◽  
Composite Resin ◽  
Endodontically Treated Teeth ◽  
Biomechanical Behavior ◽  
Fiber Posts ◽  
Strain Fracture ◽  
Significant Difference ◽  
Catastrophic Failures ◽  
Glass Fiber Posts

Restoring flared endodontically treated teeth continues to be a challenge for clinicians. This study evaluated the effect of post types and restorative techniques on the strain, fracture resistance, and fracture mode of incisors with weakened roots. One hundred five endodontically treated bovine incisors roots (15 mm) were divided into 7 groups (n=15). The two control groups were (C) intact roots restored with Cpc (cast posts and core) or Gfp (glass fiber posts). The five experimental groups were (F) flared roots restored with GfpAp (Gfp associated with accessory glass fiber posts), GfpRc (anatomic Gfp, relined with composite resin), and GfpRcAp (anatomized Gfp with resin and accessory glass fiber posts). All teeth were restored with metal crowns. Mechanical fatigue was performed with 3x10(5)/50 N. Specimens were loaded at 45º, and the strain values (μS) were obtained on root buccal and proximal surfaces. Following that, the fracture resistance (N) was measured. One-way ANOVA and Tukey's HSD tests (α=0.05) were applied, and failure mode was checked. No significant difference in strain values among the groups was found. Cpc presented lower fracture resistance and more catastrophic failures in flared roots. Gfp associated with composite resin or accessory glass fiber posts seems to be an effective method to improve the biomechanical behavior of flared roots.

Condition monitoring based on modified CUSUM and EWMA control charts

2018 ◽  
Vol 24 (1) ◽  
pp. 119-132 ◽  
Author(s):  
Suzana Paula Gomes Fernando da Silva Lampreia ◽  
José Fernando Gomes Requeijo ◽  
José António Mendonça Dias ◽  
Valter Martins Vairinhos ◽  
Patrícia Isabel Soares Barbosa
Keyword(s):  
Control Charts ◽  
Moving Average ◽  
Failure Detection ◽  
Parameters Estimation ◽  
False Alarms ◽  
Model Parameters ◽  
Content Type ◽  
Catastrophic Failures ◽  
The Right ◽  
Weighted Moving Average

Purpose The application of condition-based maintenance on selected equipment can allow online monitoring using fixed, half-fixed or portable sensors. The collected data not always allow a straightforward interpretation and many false alarms can happen. The paper aims to discuss these issues. Design/methodology/approach Statistical techniques can be used to perform early failure detection. With the application of Cumulative Sum (CUSUM) Modified Charts and the Exponentially Weighted Moving Average (EWMA) Charts, special causes of variation can be detected online and during the equipment functioning. Before applying these methods, it is important to check data for independence. When the independence condition is not verified, data should be modeled with an ARIMA (p, d, q) model. Parameters estimation is obtained using the Shewhart Traditional Charts. Findings With data monitoring and statistical methods, it is possible to detect any system or equipment failure trend, so that we can act at the right time to avoid catastrophic failures. Originality/value In this work, an electro pump condition is monitored. Through this process, an anomaly and four stages of aggravation are forced, and the CUSUM and EWMA modified control charts are applied to test an online equipment monitoring. When the detection occurs, the methodology will have rules to define the degree of intervention.

Sign in / Sign up

Export Citation Format

Share Document