Optimizing the sensitivity of the small-disc creep test to damage and test conditions

2007 ◽  
Vol 42 (5) ◽  
pp. 389-409 ◽  
Author(s):  
M Evans ◽  
D Wang

The small-creep disc test is seen as a promising solution to the problem of sampling from in-service components for remanent life estimation. However, experimental studies have revealed substantial scatter in failure times resulting from variations in test and apparatus geometries. These studies therefore suggest that there exists a set of conditions that both minimizes the scatter and also maximizes the sensitivity of the disc test to the determination of remanent life, so enabling reliable estimates of the remaining life to be made. The objective of this paper is to identify such an optimum. The large scatter present in small-disc test data would make the identification of this optimum problematic and inconclusive using an experimental approach. Instead this paper uses a numerical model of the disc test to predict failure times over a wide range of test conditions. The resulting response surface is then approximated using a polynomial and from this model the optimum set of test conditions is identified. Full verification of the model (and the optimum) can then be more successfully accomplished by carrying out experiments close to the optimum conditions where scatter is the smallest. The model was shown to be capable of predicting actual experimental creep test results. Using this approach, failure times were found to be most sensitive to disc thickness and hole diameter but least sensitive to disc diameter. Under clamping, the optimum test geometry was insensitive to the applied load but sensitive to the level of damage. Without clamping, the optimum geometry was insensitive to both of these. The paper gives optimum conditions for various levels of damage under both conditions.

2014 ◽  
Vol 70 (7) ◽  
pp. 1182-1187 ◽  
Author(s):  
Zhe Chen ◽  
Hua Li

Based on the sensitive reaction of Co(II) and salicyl fluorone with the presence of cetylpyridinium bromide in basic solution, a new method of flow injection micelle-solubilized spectrophotometry was developed for the determination of cobalt. The reaction was monitored for the absorbance of Co(II) at 540 nm. The reagents, flow injection variables and effects of foreign ions were investigated and the optimum conditions were established. At the optimum test conditions, the developed method provides a linearity range of 3–40 μg L−1 with a detection limit of 0.1 μg L−1 at about 60 h−1 sampling frequency. Relative standard deviation of 0.91, 0.95 and 0.89% were obtained for the determination of 3, 15 and 30 μg L−1 Co(II) solution. The proposed method has been successfully applied for analysis of trace amounts of cobalt in water samples.


Author(s):  
И.А. Керимов ◽  
Т.Б. Эзирбаев ◽  
А.С. Эльжаев

Выделение коллекторов нефти и газа и определение эффективных мощностей является важнейшим этапом при подсчете запасов нефти и газа. От результатов, полученных на данном этапе, напрямую зависит экономическая целесообразность ввода в эксплуатацию интервала, обладающего, признаками коллектора, фильтрационными характеристиками. Пределам таких характеристик коллекторов соответствуют кондиционные граничные значения, эти значения являются условными и могут меняться, исходя из технического уровня разработки месторождений нефти или газа на момент проведения исследований. В современных условиях быстрого развития совершенных методов разработки и изменением экономических запросов кондиционные граничные значения изменяются довольно в широких пределах. Альб-аптские отложения Терско-Сунженской нефтегазоносной области (ТСНО) относятся к сложным типам порово-трещинного коллекторов, и представлены породами песчано-алеврито-глинистых компонент. Экспериментальные исследования, проведенные на образцах кернов, взятых из терригенных отложений ТСНО позволили установить основные особенности этих отложений, обосновать основные петрофизические зависимости и определить их коллекторские свойства. В разрезе альб-аптских отложений Терско-Сунженской нефтегазоносной области в 1960-70-х гг. по известным методикам были выделены пласты-коллекторы и определены эффективные мощности. В 20092012 гг. была проведена переинтерпретация фондовых материалов результатов данных ГИС и лабораторного анализа кернов из ряда скважин основных пробуренных на нижнемеловые отложения ТСНО и предложена более совершенная методика обработки и интерпретации данных ГИС терригенных пород. В данной работе рассмотрены ранее применявшаяся методика и пример интеграции методики выделения коллекторов на основе технологии обработки и интерпретации данных ГИС ТАВС в нижнемеловых терригенных отложениях ТСНО. Важной особенностью методики комплексной интерпретации, реализованной в технологии ESKS автоматизированной системы обработки и интерпретации данных геофизических исследований скважин Gintel, является определение широкого спектра петрофизических параметров, характеризующих литологическую и флюидальную неоднородность изучаемых отложений. Это позволяет более обосновано решать задачи разведки и разработки месторождений. Методика интерпретации данных ГИС ТАВС обеспечивает определение набора геологических характеристик пород, используя которые можно определить геологическую неоднородность изучаемой толщи пород, построить детальную трехмерную геологическую модель всех продуктивных пластов в разрезе и определить их подсчетные параметры. Детальность определения геологических характеристик пород напрямую зависит от комплекса данных каротажа, зарегистрированных в скважинах. Однако особенностью методики ТАВС является то, что в ней используются системы петрофизических моделей и алгоритмические приемы обработки, которые позволяют получить максимум геологической информации об изучаемых породах даже при ограниченном комплексе данных ГИС The selection of oil and gas reservoirs and the determination of effective capacities is a critical step in calculating oil and gas reserves. From the results obtained at this stage, the economic feasibility of putting into operation an interval having, with the signs of a collector, filtration characteristics, directly depends. The limits of such reservoir characteristics correspond to conditional boundary values, these values are conditional and may vary based on the technical level of development of oil or gas fields at the time of the study. In modern conditions of rapid development of perfect development methods and changing economic demands, conditional boundary values vary quite widely. Alb-Aptian oil deposits of the Tersko-Sunzhensky oil and gas region (TSOGR) are complex types of pore-fracture reservoirs and are represented by rocks of sandy-silty-clay components. Experimental studies conducted on core samples taken from terrigenous sediments of TSOGR allowed us to establish the main features of these deposits, substantiate the main petrophysical dependencies and determine their reservoir properties. In the context of the Alb-Aptian sediments of the Tersko-Sunzhenskoye oil and gas region, by known methods, reservoirs were identified and effective thicknesses determined. In 2009-2012 reinterpretation of the stock materials of the results of well logging data and laboratory analysis of cores from a number of wells of the main fields drilled on the Lower Cretaceous deposits of TCHW was carried out and a better method for processing and interpretation of well log data of terrigenous rocks was proposed. An important feature of the integrated interpretation methodology implemented in ESKS technology of the Gintel automated geophysical data processing and interpretation system is the determination of a wide range of petrophysical parameters characterizing the lithological and fluid heterogeneity of the researched deposits. This allows us to more reasonably solve the problems of exploration and development of deposits. The technique of interpreting the GIS TABC data provides the determination of geological characteristics set for rocks, using which it is possible to determine the geological heterogeneity of the researched rock stratum, to develop a detailed three-dimensional geological model of all productive formations in a section and determine their estimated parameters. The detail of determining the geological characteristics of the rocks directly depends on the complex of logging data recorded in the wells. However, a feature of the TABC technique is that it uses systems of petrophysical models and algorithmic processing techniques that allow one to get the maximum geological information about the researched rocks even with a limited set of GIS data


Author(s):  
A. E. Segall ◽  
O. Jadaan ◽  
J. Palko

Abstract To investigate the design implications of using C-ring specimens for evaluating the strength controlling flaw population(s) of ceramics when in tubular form, finite-element analysis (FEA) calculations were performed using the ANSYS code. These calculations focused on the ranges of width-to-thickness ratios required to maintain a plane stress state within the C-ring specimen during fracture. In addition, the validity of the theoretical effective-area (KA) and effective-volume (KV) relations derived during earlier analytical and experimental studies were investigated. Results of the FEA calculations indicated that a wide range of width-to-thickness ratios could be safely used to extract fracture strength design data. Moreover, the calculations confirmed the validity of the theoretical stress-area and stress-volume relations used to correlate strength defining flaw population and determine Weibull parameters. However, a tendency for the computational errors to increase with Weibull modulus was observed during the finite-element based estimations of effective-areas and -volumes.


2011 ◽  
Vol 08 (01) ◽  
pp. 1-17 ◽  
Author(s):  
ABDEL ILLAH NABIL KORTI

There has been a growing research interest in the melting and solidification technology among mathematicians and engineers. The topic has obvious practical importance in a wide range of applications. Natural convection may play a significant role in heat transfer and hence affect the progress of the solidification. A fixed-grid finite volume numerical approach is developed and used to simulate physical details of convection flow in the solidification problems. This approach is based on the enthalpy–porosity method that is traditionally used to track the motion of the liquid–solid front and to obtain the temperature distribution and the velocity profiles in the liquid phase. The enthalpy–porosity model treats the mushy region as a porous medium. In this paper, the numerical and experimental studies of unsteady natural convection during solidification of cylindrical ingots are presented. The aim of the study consists of the numerical determination of the fluid flow, the temperature evolution, and the solidification front versus time. To validate the numerical model, an experimental study of the simple casting of cylindrical ingots was undertaken within the laboratory of metallurgy. The measured temperature was compared with values calculated numerically. A good agreement was obtained.


1964 ◽  
Vol 37 (1) ◽  
pp. 99-102
Author(s):  
B. Ya Teitelbaum ◽  
K. F. Gubanov

Abstract In the previous work of Kargin and Slonimskii and that of Kargin and Sogolov who studied the behavior of polymers over a wide range of temperature, it was shown that the shape of thermomechanical curves depends on magnitude of molecular weight of the polymers. As a result of investigation of theory and actual experimental studies in which polyisobutylene was employed, it was demonstrated that molecular weight could be estimated on the basis of thermomechanical properties. This suggested a relationship between the magnitude of molecular weight M found from the thermomechanical curves and that which was determined from glass temperatures Tg and fluid temperatures Tf. For practical use of this relationship, it is necessary to know the magnitude of the segments and two empirical constants. These values can be found by calculation of molecular weights of three different fractions of the polymer. This can be accomplished experimentally by any independent method. Once these magnitudes are determined, it is necessary to find, by means of the thermomechanical curve, the values Tg and Tf, in order to calculate the molecular weight of any sample of the same polymer. Because of the low degree of accuracy of determination of these values, and because of the peculiar differences, the reliability of the calculated molecular weight cannot be great, especially since the equation utilizes the logarithm of the molecular weight figure and not the molecular weight itself. Apparently the graphic solution is simpler than analytical methods: by means of the data of thermomechanical studies for various fractions of known molecular weights it is possible to graph the dependence of M or log Mon Tf−Tg. From what has been said, it is evident that we may use the demonstrated method only for polymers of high elasticity, and furthermore, only for those fractions in which Tf−Tg is greater than zero.


2009 ◽  
Vol 6 (2) ◽  
pp. 309-314
Author(s):  
Baghdad Science Journal

A new method for determination of allopurinol in microgram level depending on its ability to reduce the yellow absorption spectrum of (I-3) at maximum wavelength ( ?max 350nm) . The optimum conditions such as "concentration of reactant materials , time of sitting and order of addition were studied to get a high sensitivity ( ? = 27229 l.mole-1.cm-1) sandal sensitivity : 0.0053 µg cm-2 ,with wide range of calibration curve ( 1 – 9 µg.ml-1 ) good stability (more then24 hr.) and repeatability ( RSD % : 2.1 -2.6 % ) , the Recovery % : ( 98.17 – 100.5 % ) , the Erel % ( 0.50 -1.83 % ) and the interference's of Xanthine , Cystein , Creatinine , Urea and the Glucose in 20 , 40 , 60 fold of analyate were also studied .


2008 ◽  
Vol 81 (3) ◽  
pp. 470-505 ◽  
Author(s):  
K. A. Grosch

Abstract Rubber abrasion is essentially a mechanical tearing process and has been linked with the rate of a cut growth process as function of the tearing energy dissipated in the contact area between rubber and track which leads inevitably to considerable temperature rises at the points of highest stress concentration i.e. at the points at which a mechanical detachment of abraded particles is most likely. This leads to thermal degradation and oxidation as important secondary mechanisms which may well decide whether a compound performs better or worse than a reference outweighing the mechanical properties. A laboratory method has been developed, using the LAT 100 test equipment, which uses the energy dissipation and slip speeds in the contact area of a rubber sample wheel, rotating under slip, to evaluate the abrasion performance of a compound over a wide range of these variables. The resulting equations can be used either to test directly the correlation between laboratory and road test results which is usually good over a limited range, or they are used in a road test simulation program with well defined road test conditions. The latter gives a set of single compound ratings and tire lives. These depend however strongly on the chosen test conditions and in that they reflect reality


2013 ◽  
Vol 13 (02) ◽  
pp. 1250069 ◽  
Author(s):  
H. Y. BAN ◽  
G. SHI ◽  
Y. J. SHI ◽  
Y. Q. WANG

This paper presents the results of the experimental studies conducted on the buckling behavior of 420 MPa high strength steel, hot-rolled, equal angle columns, numbering a total of 66 specimens with a wide range of column slenderness and section sizes. Based on the test results, the buckling modes and capacities were analyzed and the nondimensional buckling strengths were obtained and compared with the design strength predicted from Eurocode 3, ANSI/AISC 360-10 and Chinese standards GB50017-2003. The experimental results in previous studies were also employed in the comparison. The effect of width to thickness ratio of legs of an angle on buckling modes and strengths were investigated. It was found that the buckling strengths from test results were much higher than the corresponding design values and current design approaches were too conservative. Based on present and previous experimental results, a new design approach is suggested for the design of angle columns with 420 MPa high strength steel.


2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Vedat DENIZ

Grindability measurements are widely used in mineral and coal processing industry to determine resistance of materials to comminution.Grindability measurement as testing methods can be divided into two general categories; the Bond and the Hardgrovegrindabilities. Grinding characteristics of the mineral or coal blending have been studied by several researchers over many yearsand a wide range grinding variables has been investigated. In this study, because of the simplicity and the potential usage of themethod for the determination of the grindability of coals and their blending in a comparative scale, a Hardgrove mill were used toinvestigated the grinding behavior of four different solid fuels and their blending. Grindability of four different solid fuels such as;petroleum coke, coke coal, lignite and bituminous coal and their binary, ternary and quaternary blending were investigated by theHardgrove grindability test. The test results indicated that determine the existence of a very good relation between the Bond andthe Hardgrove grindability of the fuels, and relationship between experimental and calculated HGI values of the fuels blendingwere also shown as a very good. However, there is not obtain a good relation between proximate analysis results of the solid fuelsand HGI values of fuels blending.


2020 ◽  
Vol 65 (1) ◽  
pp. 103-109
Author(s):  
Aleksandr Shubenko ◽  
Vladimir Goloshchapov ◽  
Daria Senetska ◽  
Oleksandr Senetskyi

On the basis of the one-dimensional theory of calculating the operation of steam turbine stages the method for determining the idle mode, the initial data for which are the geometric characteristics of the blade rows is proposed. Formulas have been obtained that make it possible to calculate the efficiency in the proximity of Rotor Blades (RB) at operating modes from nominal to the idle mode, depending on the flow rate of the stage and taking into account the use of kinetic energy with the runaway velocity and losses arising at off-design angles of flow on the Rotor Blade (RB). The results of possible computational studies and their comparison for an incompressible working fluid with the results of experimental studies showed the good possibilities of the proposed method for determining the idle mode in a wide range of the characteristics of stages.


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