Papers by Keyword: Weibull Distribution

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Authors: Winston O. Soboyejo, W. Shen, J. Lou, C. Mercer, V. Sinha, Alfred B.O. Soboyejo
Authors: Hui Liang Li
Abstract: In this paper, a series of numerical control machine tool truncated failure data collect.The data are assumed to be two parameter weibull distribution and related parameters is obtained and relevant inspection and test of hypothesis, it is concluded that the mathematical model of batch of nc machine tool failure interval time distribution.Relevant indicators to determine the reliability of nc machine tools, machine tool's observations, Machine tool observations, point estimation and interval estimation index value provide a theoretical basis for the research on reliability of machine tool.
Authors: Kai Duan, Xiao Zhi Hu
Abstract: A simple means of deconvoluting the size distributions of fracture-controlling flaws from Weibull strength plots for small-scale specimens is proposed. The method makes use a power-law distribution function, empirical in form but self-consistent with a conventional two-parameter Weibull probability distribution. Literature data for single-crystal silicon beam specimens covering a range of widths from mm to nm are analyzed according to this procedure. The analysis indicates a reduction in scatter in addition to increase in strength with diminishing specimen size, and quantifies a systematic tightening in flaw distribution associated with refinement in fabrication method.
Authors: Hua Lin Liao
Abstract: Based on the probability distribution theory of rock micro-unit strength and taking the Mohr-Coulomb damage criterion as the distribution variable, the theoretical equations for the evolution of damage variables and the statistical constitutive model of rock damage in triaxis test were established. The arbitrary triaxis experimental data w ere used to calculate the parameters in the model by using curve fitting method and extreme value method. The calculated results of the model agree well with the experimental data. This constructive model can reflect effectively the deformation characteristics of rocks under loads and the constructive relation between elastic strain and stress of rock damage.
Authors: Y.B. Lee, Hyoung Eui Kim, J.H. Park, J.M. Ko
Abstract: There are several types of life test method for hose assemblies. The two major tests used for hose assemblies are impulse test and burst test. And magnification adjustment of impulse pressure, heating of testing oil and repetitive motions of bending and straightening of testing hose are also performed for accelerating the life. According to the manufacture process of hose and swaging process of fitting, there is a difference in the life of hose assemblies from minimum 7 times to maximum 40 times during the life test in the same functioning condition. Like this, the life test of hose which has a wide scope of life distribution gives a problem that observation should take a long time to find out the existence of the bursting from the beginning of the test to the completion of bursting of hose assemblies. Therefore, this research proposes a process of concentrating on the defective section of hose assemblies and maximizing the life acceleration by giving ‘Knockdown stress’ to hose assemblies just until before the hose assemblies get out of order.
Authors: Fen Hua Ren, Xing Ping Lai
Abstract: Based on MTS-815.02 servo-controlled rock mechanics and acoustic emission (AE) integrated test system, the strength, shear deformation localization and damage AE-energy-rate characteristics process of coal specimen from Weihuliang Coal Mine under tri-axial loading were analyzed. A new model of Weibull distribution on the AE higher energy-rate emergence interval under tri-axial loading had been established, the total probability of coal sample localization failure in an interval is proposed. Then, the forecasting analysis of the coal fracture failure can be studied. The results indicate that the Weibull distribution of the AE higher energy-rate emergence were similar to the experimental results that measured. It is very important to the identification and ration prediction of coal failure in the mining.
Authors: Mohamed Salem Elmnefi, Ahmed Mohamed Bofares
Abstract: The statistical wind data obtained from measurements for the 12 month period of January to December 2008 at Benina, Benghazi, Libya. The site coordinates are: latitude 32,05N and longitude 20,13E. The elevation of the site is 136 m above mean sea level (AMSL). The wind speed has been measured at height of 10 m above the ground level using 3 cup anemometers. Moreover wind speed has been estimated at height of 40 m. The statistical wind data set was analyzed using weibull distributions in order to investigate the weibull shape and scale parameters at 10 m and 40 m height. Finally, the yearly power density has been estimated at both heights. The results showed that strong and sufficient winds for power generation are available at most of months in Benina region.
Authors: Chul Su Kim, Jung Kyu Kim, Tae Seong Kim
Abstract: In order to evaluate the variation of fatigue data of turbine blade steel in low pressure (LP) steam, it is important to estimate probabilistic stress-life (P-S-N) curve to accurately define the probability distribution. In this study, a new procedure was introduced to determine the expression of P-S-N curves. For this purpose, 3-parameter Weibull distribution was found to be the most appropriate among assumed distributions when the probability distributions of the fatigue life were examined by a comparative analysis. Furthermore, the parameter of P-S-N curve was evaluated using various optimization techniques to maximize the correlation coefficient. As a result, the sequential linear program method is used for estimation of P-S-N curve.
Authors: Jing Zhao, Li Hua Sun, Yong Chun Liang, Cai Hong Yan, Hui Wang
Abstract: In the field of electric appliances’ reliability, the constant-stress accelerated-life-test is commonly used to test the reliability of electric appliances. A new analysis method based on constructed data is introduced to analyze the constant-stress accelerated-life-test data of electric appliances under Weibull distribution. The correlation between shape parameter and characteristic life is took into account and the estimated value of characteristic life is modified, which increase the model fitting optimization and improve the analysis precision. Moreover, the method avoids table lookup and is easy to be realized by computer software in the application of reliability engineering for electric appliances.
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