Deep online oil analysis of dielectric parameters for life time enhancement of industrial gearboxes – Identification of critical operation conditions for reduction of failure rates

2019 ◽  
pp. 245-256
Author(s):  
M. R. Mauntz ◽  
J. Peuser
Keyword(s):  
Life Time ◽  
Oil Analysis ◽  
Failure Rates ◽  
Dielectric Parameters ◽  
Operation Conditions

scholarly journals Life-time prediction for aviation GTE compressor disk based on mixed-mode and multi-axial fracture resistance parameters

2019 ◽  
Vol 300 ◽  
pp. 11001
Author(s):  
Valery Shlyannikov ◽  
Ivan Ishtyryakov ◽  
Rustam Yarullin
Keyword(s):  
Crack Growth ◽  
Structural Integrity ◽  
Growth Models ◽  
Process Zone ◽  
Life Time ◽  
Elastic Plastic ◽  
Time Prediction ◽  
Operation Conditions ◽  
Nonlinear Stress ◽  
Compressor Disk

This study is concerned with analysis of fatigue crack growth and life-time prediction for aviation GTE compressor disk under operation conditions. For consideration were different combinations of rotational speed, temperature, surface flaw form and sizes as well as elastic-plastic titanium alloy BT3-1 properties are employed. A crack growth rate equation is derived involving the fracture process zone size and nonlinear stress intensity factor. The assessments of the structural integrity of the rotating disk are compared for elastic and elastic-plastic solutions. It is stated that the traditional elastic crack growth models overestimate the residual fatigue lifetime with respect to the nonlinear fracture mechanics approach.

Beyond Life: Including Risk and Consequence in Maintenance Planning

2015 ◽  
Author(s):  
Pontus Slottner
Keyword(s):  
Gas Turbine ◽  
Failure Modes ◽  
High Sensitivity ◽  
Life Time ◽  
Relative Sensitivity ◽  
Probabilistic Methods ◽  
Plant Design ◽  
Efficient Manner ◽  
Hybrid Approaches ◽  
Operation Conditions

Adequate and timely maintenance is a tool to improve the value of equipment by ensuring that potential risks are mitigated in a timely and efficient manner thereby increasing the return on investment of the equipment. In practice, this means that every maintenance activity needs to eliminate a known or predicted future cost of maintenance, loss of production, other consequence costs of failures or any combination of the above that is more expensive than the maintenance action itself. Different approaches to this optimization problem have been suggested over the years including model based physical as well as purely numerical and hybrid approaches. This paper discusses an attempt to combine failure consequence analysis methods and probabilistic methods with classical prognostics methods for a gas turbine blade where the life time show high sensitivity to operation conditions and multiple failure modes are active. Applications of the results are discussed. The conclusions indicate that the shape of failure data can be a strong indicator on the relative sensitivity of reliability to changes in quality of parts and workmanship, overall plant design and gas turbine maintenance.

scholarly journals A BRIEF LOOK AT DATA ON THE RELIABILITY OF SPRINKLERS USED IN CONVENTIONAL BUILDINGS / TRUMPA DUOMENŲ APIE ĮPRASTINIUOSE PASTATUOSE ĮRENGTŲ SPRINKLERIŲ PATIKIMUMĄ APŽVALGA

2011 ◽  
Vol 17 (1) ◽  
pp. 115-125 ◽  
Author(s):  
Egidijus Rytas Vaidogas ◽  
Jurgita Šakėnaitė
Keyword(s):  
Data Collection ◽  
Failure Modes ◽  
Reliability Assessment ◽  
Critical Issue ◽  
Theoretical Modelling ◽  
Data Sets ◽  
Failure Rates ◽  
Industrial Facilities ◽  
Operation Conditions ◽  
Component Failure Rates

Failures of sprinklers to extinguish fires generate a basic need for the assessment and increase of reliability of these crucial safety systems. This in turn creates a demand for input data used for reliability assessment. Broadly speaking, data on sprinkler failures are available in large amounts and some countries have well-established systems of data collection and reporting. Data are accumulated in the sprinklered environments of conventional buildings and some industrial facilities. The compilation of data sets necessary for reliability assessment may face several problems: differences in definition and naming failure modes; differences in the failure of data reporting; the prevalence of a human factor among the causes of sprinkler failures in a conventional building; the influence of ageing, modifications and repairs on sprinkler reliability. The size of data sets can be limited by such factors as limited relevance of data collected in different sprinklered environments, differences in operation conditions and components, ageing of data collected in the past, the concealment of data and/or a high cost of data, poor documentation and explanation of data in available databases. Data on sprinkler component failure rates necessary for fault tree models can be extracted from generic databases. However, databases containing information on the failure rates of sprinkler-specific components do not seem to exist in literature or on the Internet. Scarce data on sprinkler failures can be utilised within the Bayesian format. The potentially critical issue of reliability dependence on sprinkler aging and other changes in time remains unsolved from the standpoint of both theoretical modelling and data collection. Santrauka Nereti sprinklerių atsakai, gesinant gaisrus, verčia vertinti šių kritinių saugos sistemų patikimumą. Dėl to reikia kaupti ir apdoroti duomenis, kurių reikia vertinant patikimumą. Duomenų apie sprinklerių atsakus yra daug. Kai kurios šalys turi gerai sudarytas sprinklerių patikimumo duomenų rinkimo ir skelbimo sistemas. Duomenys renkami apie sprinklerius, įrengtus tiek įprastiniuose pastatuose, tiek pramoniniuose objektuose. Tačiau duomenų patikimumui vertinti rinkimas susiduria ir su kai kuriais sunkumais. Nėra sutartinės sprinklerių atsakų apibrėžimo ir įvardijimo praktikos, ataskaitos apie atsakus dažnai labai skiriasi, patikimumo vertinimą sunkina ir tai, kad vyraujanti įprastinių pastatų sprinklerių atsakų priežastis yra žmonių klaidos. Patikimumo vertinimą apsunkina ir sprinklerių senėjimo reiškinys, sistemų modifikavimai ir remontai. Patikimumo duomenų kiekį riboja ir tai, kad duomenys, gauti skirtingose eksploatavimo aplinkose, tinka tik toms aplinkoms. Sprinklerių eksploatacija ir aplinkos sąlygos gali būti skirtingos. Duomenų kiekį riboja ir jų kaina, senėjimas bei slėpimas. Duomenys, kaupiami kai kuriose bazėse, būna nepakankamai paaiškinti ir netinkamai dokumentuoti. Kai sprinklerių sistemos patikimumas vertinamas taikant atsakų medžio analizę, įvesties duomenys gali būti gauti ir iš bendrųjų patikimumo duomenų bazių. Tačiau literatūroje ir internete negalima rasti duomenų bazės, kurioje būtų sukaupti duomenys būtent apie sprinklerių sistemų komponentų patikimumą. Kai patikimumo duomenų trūksta, jį galima vertinti taikant Bajeso metodus. Tiek teorinis modeliavimas, tiek duomenų rinkimas šiandien dar neleidžia atsižvelgti į fizinį sprinklerių senėjimą bei modifikacijas, kurios gali labai paveikti šių sistemų patikimumą.

SEM and Auger microanalysis studies of Cu-Be dynode surfaces at each activation condition

1978 ◽  
Vol 36 (1) ◽  
pp. 524-525
Author(s):  
T. Koshikawa ◽  
Y. Fujii ◽  
E. Sugata ◽  
F. Kanematsu
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Life Time ◽  
Activation Process ◽  
Beam Diameter ◽  
Activation Temperature ◽  
Electron Multiplier ◽  
Activation Condition ◽  
Activation Conditions

The Cu-Be alloys are widely used as the electron multiplier dynodes after the adequate activation process. But the structures and compositions of the elements on the activated surfaces were not studied clearly. The Cu-Be alloys are heated in the oxygen atmosphere in the usual activation techniques. The activation conditions, e.g. temperature and O2 pressure, affect strongly the secondary electron yield and life time of dynodes.In the present paper, the activated Cu-Be dynode surfaces at each condition are investigated with Scanning Auger Microanalyzer (SAM) (primary beam diameter: 3μmϕ) and SEM. The commercial Cu-Be(2%) alloys were polished with Cr2O3 powder, rinsed in the distilled water and set in the vacuum furnance.Two typical activation condition, i.e. activation temperature 730°C and 810°C in 5x10-3 Torr O2 pressure were chosen since the formation mechanism of the BeO film on the Cu-Be alloys was guessed to be very different at each temperature from the results of the secondary electron emission measurements.

Negative Life Events Associated With Deliberate Self-Harm in an African Population in Uganda

Crisis ◽  
2005 ◽  
Vol 26 (1) ◽  
pp. 4-11 ◽  
Author(s):  
E. Kinyanda ◽  
H. Hjelmeland ◽  
S. Musisi
Keyword(s):  
Life Events ◽  
Negative Life Events ◽  
Life Time ◽  
Later Life ◽  
Dose Effect ◽  
Deliberate Self Harm ◽  
Time Period ◽  
Significant Difference ◽  
Self Harm ◽  
Suicide Interventions

Abstract. Negative life events associated with deliberate self-harm (DSH) were investigated in an African context in Uganda. Patients admitted at three general hospitals in Kampala, Uganda were interviewed using a Luganda version (predominant language in the study area) of the European Parasuicide Study Interview Schedule I. The results of the life events and histories module are reported in this paper. The categories of negative life events in childhood that were significantly associated with DSH included those related to parents, significant others, personal events, and the total negative life events load in childhood. For the later-life time period, the negative life events load in the partner category and the total negative life events in this time period were associated with DSH. In the last-year time period, the negative life events load related to personal events and the total number of negative life events in this time period were associated with DSH. A statistically significant difference between the cases and controls for the total number of negative life events reported over the entire lifetime of the respondents was also observed, which suggests a dose effect of negative life events on DSH. Gender differences were also observed among the cases. In conclusion, life events appear to be an important factor in DSH in this cultural environment. The implication of these results for treatment and the future development of suicide interventions in this country are discussed.

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