Allocation of the wear of the main support of raba-man cylinders blocks

2020 ◽  
pp. 20-27
Author(s):  
Dar’ya A. Lebedeva ◽  
Vitaliy A. Zuyevskiy ◽  
Il’ya V. Romanov
Keyword(s):  
Statistical Processing ◽  
Integral Function ◽  
Distribution Functions ◽  
Theoretical Distribution ◽  
Research Purpose ◽  
Design Stage ◽  
Distribution Law ◽  
Statistical Series ◽  
Distribution Laws ◽  
Main Support

Wear of the main supports is a defect of many domestic and foreign engines. Statistical processing and selection of the theoretical distribution of the wear greatly simplifies the choice of recovery methods at the design stage. (Research purpose) The research purpose is choosing the theoretical law of wear allocation of the main supports of Raba-MAN cylinder blocks. (Materials and methods) Authors carried out statistical processing of micrometric data of the main supports of Raba-MAN cylinder blocks. Authors measured the diameters of the main supports of 40 cylinder blocks Raba-MAN three times with tightened fastening bolts with NI 100-160 GOST 868-82 micrometer with a step of 0.01 millimeters. Authors evaluated the match of experimental and theoretical distribution laws by Pearson’s criterion. (Results and discussion) The measurements results were summarized in a statistical series. The article presents a histogram of accumulated experimental probabilities and graphs of differential and integral distribution functions. It was found that the probability of matching of experimental and theoretical distribution laws for both laws is less than 10 percent. Article notes that the chosen distribution laws are not characterized by the presence of the second peak on the graph of the differential function, and the slope of the curve of integral function when approaching the last interval is much higher than the theoretical curves functions. (Conclusion) The maximum wear does not exceed 0.16 millimeters. Since the most common laws of normal distribution and Weibull distribution in statistical calculations are unsuitable in this case, additional research is required to select the theoretical distribution law.

scholarly journals Reliability and Lifetime Assessment of Glider Wing’s Composite Spar through Accelerated Fatigue Life Testing

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2310 ◽  
Author(s):  
Sebastian Marian Zaharia ◽  
Mihai Alin Pop ◽  
Răzvan Udroiu
Keyword(s):  
Sandwich Structures ◽  
High Reliability ◽  
Statistical Processing ◽  
Bending Test ◽  
Design Stage ◽  
Test Time ◽  
Glass Fiber Reinforced Plastic ◽  
Reliability Indicators ◽  
Inverse Power Law ◽  
Number Of Cycles

The evaluation of the reliability and the lifetime of aerospace components has become an important segment of the design stage. The aeronautical components are subjected to complex, rigorous tests and have a long test life. The main goal in the field of aviation is to have components with high reliability and quality and to meet the mandatory requirements and regulations. The spars are stiffening components positioned along the wing and which take up most of the load and are tested for fatigue over a long period of time. The spar which was analysed in this study has a sandwich structure with GFRP (glass fiber reinforced plastic) skin and foam core. In this paper, the performances in the static and dynamic conditions of the GFRP-foam sandwich structures cut out of the composite spar of a glider were analysed. Additionally, using accelerated techniques based on the three-point fatigue bending test, the main reliability indicators of the GFRP-foam sandwich structures were determined. Using the statistical processing of the experimental data and the Inverse Power Law–Weibull acceleration model, the mean number of cycles to failure, in normal testing conditions of the GFRP-foam specimens was determined, with a value of 102,814. Using the accelerated testing techniques of the GFRP-foam sandwich structures an important decrease of the test time (8.43 times) was obtained.

Technological Principles for the Formation of Instrument Structures with Reproducible Parameters

2020 ◽  
Vol 22 (9) ◽  
pp. 489-492
Author(s):  
M.G. Mustafaev ◽  
◽  
G.A. Mustafaev ◽  
D.G. Mustafaeva ◽  
◽  
...  
Keyword(s):  
Production Process ◽  
Technological Process ◽  
Failure Mechanisms ◽  
Statistical Processing ◽  
Dielectric Strength ◽  
Design Stage ◽  
Statistical Relationships ◽  
Materials Used ◽  
The Stability ◽  
The Relationship

It is shown that increasing the role of control methods, identifying patterns and accuracy of performing technological operations, establishing the relationship between the characteristics of the technological process and the yield of suitable products, will ensure the reproducibility of technology and the formation of instrument structures with specified parameters. In the technological process of production, instrument structures are formed and constructive and technological foundations are implemented, on which the specified parameters are established in technological and final tests. Providing the specified parameters of device structures, depending on the production processes, is carried out on the basis of increasing the dielectric strength of oxide layers, improving the production process, and reducing the number of defects in oxide films. Improving the cleanliness during the production process allows you to reduce the level of defective structures. The inconsistency of the coefficients of thermal expansion of the materials used is the cause of failures of elements of integral electronics and a decrease in their reliability. Analysis of thermal effects and associated mechanical loads allows one to assess the optimality of the selected materials and to clarify the likely failure mechanisms. Knowledge of the failure mechanisms makes it possible to calculate the reliability of the device at the design stage, as well as to predict the reliability of the equipment being developed. The reproducibility of the technology is ensured by conducting a statistical analysis of the technological process, containing statistical processing, establishing statistical relationships between parameters, determining the regularities of the technological process, constructing regression models for the relationship between the yield of good products and modes of technological operations, and analyzing the stability of the technological process. The traceability of the relationship between the parameters of instrument structures and the technology of their manufacture allows to reduce the level of their defectiveness, statistical regulation, based on the measured values of the parameters, and determining their position relative to the regulation limits, ensures the accuracy of the production process.

Residual Oil Distribution Law and Controlling Factors of Chang 6 Reservoir in Liutai Area

2014 ◽  
Vol 1010-1012 ◽  
pp. 1735-1739
Author(s):  
Feng Run Zhang ◽  
Ai Hua Guo ◽  
Huai En Cai
Keyword(s):  
Sedimentary Facies ◽  
Geological Structure ◽  
Controlling Factors ◽  
Water Flooding ◽  
Residual Oil ◽  
Distribution Law ◽  
Total Recovery ◽  
Main Layer ◽  
Oil Distribution ◽  
Distribution Laws

Because of the high heterogeneity, late water flooding and irregular well network, the distribution law of residual oil reserve in Chang 6 reservoir becomes much complicated. Combining the geology with dynamics of the reservoir, volumetric and formation coefficient methods are adapted to calculated the residual reserves, and then the distribution laws and controlling factors are analyzed. The results indicate that: there are still large amounts of residual reserve in main layer Chang 622; the residual reserve can be classified into three kinds, Class I and class II are distributed concentrative in main layer; the controlling factors include property, sedimentary facies, heterogeneity, well network controlling and geological structure and so on. Finally, according to the distribution laws and controlling factors, targeted measures are proposed. The studying results provide well foundations for improving recovery of residual oil reserves and the total recovery of the reservoir.

scholarly journals TO THE STATISTICAL ANALYSIS OF SOIL SHEAR TESTS RESULTS

2020 ◽  
Vol 11 (3) ◽  
pp. 8-17
Author(s):  
A. M Karaulov ◽  
K. V Korolev ◽  
L. A Bartolomey ◽  
E. P Bragar
Keyword(s):  
Normal Distribution ◽  
Sandy Loam ◽  
Statistical Processing ◽  
Sandy Soils ◽  
Random Variable ◽  
Soil Strength ◽  
Strength Characteristics ◽  
Shear Tests ◽  
Strength Parameters ◽  
Distribution Law

The result of any shear tests, which are the most popular laboratory methods for determination the strength characteristics of soils, is a set of values of the ultimate shear resistance and the corresponding normal pressure along the shear section. The theoretical background for the analysis of the soil shear tests results is the theory of probability and mathematical statistics. At the same time, we have questions about the determination of the calculation values of soil strength parameters. So, during the processing of shear tests results according to a consolidated-drained scheme for sandy soils the calculation values of soil specific cohesion are often negative, which is incorrect. The article considers an example of processing of shear tests data of sandy loam for various normal pressures, and analyzes the results of statistical processing of soil tests. The normative methods for probabilistic assessment of soil strength characteristics are based on using of normal distribution law of a random variable. It is assumed that the valuesof a random variable can vary from -¥ to +¥, while the soil strength parameters can vary in a limited range, i.e. accept only positive valuesfrom 0 to +¥. This circumstance does not matter for the majority of clayed soils, which strength parameters are far enough from zero. However, it has a significant effect on the result for small sought-for values, particularly, in assessing of specific cohesion for sandy soils. Therefore, for such cases, the article presents a variant of the statistical processing of the shear tests results with using the reduced normal distribution law of a random variable.

scholarly journals CORRECTION OF TRANSFORMER OIL BREAKDOWN VOLTAGE MAXIMUM PERMISSIBLE VALUES BY THE MINIMUM RISK METHOD

2020 ◽  
pp. 105-114
Author(s):  
O. V. Shutenko ◽  
S. H. Ponomarenko
Keyword(s):  
Breakdown Voltage ◽  
A Priori ◽  
Risk Function ◽  
Statistical Processing ◽  
Transformer Oil ◽  
Economic Damage ◽  
Average Risk ◽  
Distribution Laws ◽  
Transformer Oils ◽  
The Given

The method of correction of maximum permissible values of breakdown voltage of transformer oils in order to minimize possible economic damage in case of making erroneous decisions during diagnostics of the condition of transformer oils according to the results of periodic tests is proposed. An algorithm for statistical processing of the periodic test results is described, the use of which allows forming arrays with homogeneous values of the indicators under a priori limited measuring information. Analysis of distribution laws of breakdown voltage values for the transformer oils suitable and unsuitable for operation according to the values of this indicator is done. According to the results of the analysis, it was found that the breakdown voltage values of oils with different states have Weibull distribution. It was determined that the values of mathematical expectations of breakdown voltage of serviceable oils with the ageing of transformer oils shifts to the area of low values. It means that the breakdown voltage maximum permissible values of oils for the given distributions should be different. It is confirmed by the previously known fact that for unimodal distributions, the maximum permissible values of indicators that provide a minimum of risk are in an interval bounded by the mathematical expectation of the indicator distributions with different states. A decisive rule is formulated and an average risk function is compiled to adjust the maximum permissible breakdown voltage values of transformer oils. Based on the minimisation of the average risk function by Newton's method, the maximum permissible values of the breakdown voltage of oils have been determined. The made comparative analysis has shown that the correction of maximum permissible values of breakdown voltage of oils allows decreasing the risk values by 1.52÷19.13 times in comparison with risks, which provide the use of maximum permissible values, regulated in standards. It was found that the maximum permissible values of the breakdown voltage of oils, providing a minimum value of average risk, are not constant. They vary depending on the values of faulty decision prices and the probabilities of occurrence of different defective and defect-free oil states of transformers.

Crest-Height Distribution in Nonlinear Random Wave

2009 ◽  
Author(s):  
Cuilin Li ◽  
Dingyong Yu ◽  
Yangyang Gao ◽  
Junxian Yang
Keyword(s):  
Nonlinear Wave ◽  
Wave Theory ◽  
Distribution Functions ◽  
Theoretical Distribution ◽  
Distribution Model ◽  
Stokes Wave ◽  
Wave Crest ◽  
Linear Wave ◽  
Height Distribution ◽  
Crest Height

Many empirical and theoretical distribution functions for wave crest heights have been proposed, but there is a lack of agreement. With the development of ocean exploitation, waves crest heights represent a key point in the design of coastal structures, both fixed and floating, for shoreline protection and flood prevention. Waves crest height is the dominant parameter in assessing the likelihood of wave-in-deck impact and its resulting severe damage. Unlike wave heights, wave crests generally appear to be affected by nonlinearities; therefore, linear wave theory could not be satisfied to practical application. It is great significant to estimate a new nonlinear wave crest height distribution model correctly. This paper derives an approximation distribution formula based on Stokes wave theory. The resulting theoretical forms for nonlinear wave crest are compared with observed data and discussed in detail. The results are shown to be in good agreement. Furthermore, the results indicate that the new theoretical distribution has more accurate than other methods presented in this paper (e.g. Rayleigh distribution and Weibull distribution) and appears to have a greater range of applicability.

scholarly journals An Asymptotic Formula for a Class of Distribution Functions

1935 ◽  
Vol 4 (3) ◽  
pp. 138-143
Author(s):  
E. W. Cannon ◽  
Aurel Wintner ◽  
A. C. Aitken
Keyword(s):  
Asymptotic Formula ◽  
Asymptotic Behaviour ◽  
Random Variables ◽  
Distribution Functions ◽  
Independent Random Variables ◽  
Distribution Law ◽  
General Conditions

If x1, x2, …., xk, …. are independent random variables each of which is subjected to a distribution law σ = σ(x) independent of k and having a finite positive dispersion, then x1 + x2 + …. + xn is known to obey the Gauss law as n→ + ∞, no matter how σ (x) be chosen. There arises, however, the question whether it is nevertheless possible to determine the elementary law σ (x) from the asymptotic behaviour of the distribution law of x1 + x2 + …. + xn for very large but finite values of n. It will be shown that the answer is affirmative under very general conditions.

scholarly journals Statistical modeling of the assembly of single-layer domes

2019 ◽  
Vol 97 ◽  
pp. 04004
Author(s):  
Evgeny Lebed
Keyword(s):  
Numerical Modeling ◽  
Computational Geometry ◽  
Normal Distribution ◽  
Single Layer ◽  
Statistical Processing ◽  
Statistical Simulation ◽  
Assembly Process ◽  
Distribution Law ◽  
Computational Procedures ◽  
Multiple Assembly

A special purpose software SBORKA was developed by the author, which is intended for numerical modeling of the assembly process of single-layer lattice domes with respect to random deviations in lengths of individual bars. The dispersion of the inaccuracies in the sizes of bars is consistent with the normal distribution law, and their values are limited by the tolerances corresponding to 3σ. The assembly of a single-layer dome frame is simulated by sequentially calculating the coordinates of its nodes based on the imitation of the connection in these nodes of individual bars. Imperfections in the lengths of the bars lead to the fact that the actual geometric shape of the dome frame will differ from the design shape. Reliable analysis of the nature of the possible errors of the frames of single-layer lattice domes can only be performed by multiple assembly simulations with subsequent statistical processing of the obtained results. For the implementation of numerical statistical simulation of the assembly, the algorithm of the software includes procedures for solving various spatial problems of computational geometry. Computational procedures implemented in the software for modeling the assembly process are described in this paper.

Impact on the track from EMU commuter train

2018 ◽  
Vol 77 (4) ◽  
pp. 191-199
Author(s):  
A. M. Brzhezovskiy
Keyword(s):  
Statistical Processing ◽  
Travel Speed ◽  
Outer Edge ◽  
Rolling Stock ◽  
Design Stage ◽  
Customs Union ◽  
Technical Parameters ◽  
Test Loop ◽  
Impact Indicators ◽  
The Impact

The largest part of operating fleet of EMU trains, operated on the railways of the JSC “Russian Railways”, belongs to the category “ЭП” - electric commuter trains for transporting passengers in suburban areas with a length of the turnover section not exceeding 200 km with a speed of up to 120 km/h. The category of “ЭП” electric trains is fully formed by the domestic rolling stock produced since 1993. After putting Safety Norms NB ZhT 03-98 into force in 1998 and subsequently entering Technical Regulations of the Customs Union - TR TS 001/2011 virtually all new or upgraded series of EMU trains of the category «ЭП» within the acceptance and certification tests were experimentally investigated by the Test Loop of the JSC “VNIIZhT” (ITs ZhT) for compliance with safety requirements from the conditions for ensuring normative level of indicators of interaction between rolling stock and the track. Main technical parameters were shown as well as design features of carriage part of EMU trains of the category “ЭП”. The following features were considered: comparative quantitative values and dependencies on the travel speed and the level of unbalanced accelerations of the experimental indicators of influence on the track of EMU train cars of the category “ЭП”, determined from the results of statistical processing of realizations of dynamic stresses in the throttle of rail sole and lateral forces; vertical and lateral (horizontal) forces transmitted from the wheels to the rail head; stability coefficients of assembled rails and sleepers from the transverse shift along the ballast, as well as the coefficients f of the transition from the axial stresses in the base of the rail to the stresses in the outer edge of the rail sole. The quantitative values of the impact indicators on the track of EMU train cars of the category “ЭП” with a design speed of 120 km/h, obtained from the results of complex certification and acceptance tests, are in the range of values regulated by the current regulatory documents. It is recommended to use the values of the impact indicators on the track to evaluate the design of the carriage part of EMU train cars at the design stage.

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