Papers by Keyword: Weibull Distribution

Abstract: This paper presents a new approach for reliability test sampling plan of Railway equipment. Based on the interval censored failure data, the mean rank order method is used for data pre-process and the least square method is used for fitting the parameters of Weibull distribution, where, the best estimations of distribution parameters are derived. The sampling inspection plan for interval censored data is established when the lifetime follows the Weibull distribution. In the case study, we applied the proposed method to design the reliability test sampling plan of an electric multiple units.

Abstract: In this paper we report TDDB results on SiO₂/SiC MOS capacitors fabricated in a matured production environment. A key feature is the absence of early failure out of over 600 capacitors tested. The observed field accelerations and activation energies are higher than what is reported on SiO₂/Si of similar oxide thickness. The great improvement in oxide reliability and the deviation from typical SiO₂/SiC observations are explained by the quality of the oxide in this study.

Abstract: Wind energy is an important alternative energy resource because of it clean, does not cause pollution and it can be used as replacement of a fossil fuel energy. Utilization of the wind energy, the wind speed data has to be analyzed to make sure before use it. In this article is to present the wind speed data analysis by using Weibull distribution method. Wind speed data from the meteorological station at Pakchong district, Nakhonratchasima province, Thailand was used as the case study. The results show that this area has wind speed about 2.5 to 3.5 m/s. The average wind power density was 17.513 W/m² and the total wind energy was 153.9819 kW·hr/m² per year. This wind potential of this area can be used for water pumping and electricity generating for use in a household.

Abstract: Polymeric material such as low density polyethylene (LDPE) has been used for decades as insulating material. Any polymeric material will experience degradation after prolonged application of high electrical stresses. Deeper understanding of the long term electrical degradation of the insulating material is necessary to predict the life of high voltage cable. Electroluminescence method (EL) is used to detect the breakdown voltages of thin film LDPE. This method utilizes a Peltier cooled electron multiplying charge coupled device (EMCCD) camera to detect the breakdown of the sample. Statistical distribution of the AC breakdown voltages of 100μm virgin and aged LDPE has been analysed. Comparison for the best fitted distribution was made for Weibull distribution and Johnson SB distribution using Anderson-Darling (A2) goodness-of-fit and Kolmogorov-Smirnov (D) goodness-of-fit (GOF). Johnson SB is rarely used in high voltage engineering application. The probability density function (PDF) and the cumulative density function (CDF) for both distributions are defined in this article. The statistical parameters used are estimated based on Maximum Likelihood Estimation (MLE) for both distributions. Based on the statistical analysis, it is observed that Johnson SB provide better fitting than Weibull distribution with lower fitting error and that 3-parameter Weibull is much better fitting than 2-parameter Weibull distribution for most cases. It is also found that the median breakdown voltage of LDPE samples decreases with increasing aging temperature.

Abstract: The aim of this paper is to analyze the reliability of freight wagon wheelset on the basis on real field data, observed and collected in actual operations of freight wagons. The failure modes and their associated occurrence absolute frequencies are identified and a Pareto analysis is carried out.The Weibull probability distribution is used to determine the reliability mathematical model for railway wheelset. The probability law is linearized, allowing the use of linear regression to estimate, on the basis of empirical data, the˰̸̵̱̓̀˰̵̵̱̱̀͂̽̈́͂˰ڂ˰̴̱̾˰̸̵̈́˰̵̳̱̼̓˰̵̵̱̱̀͂̽̈́͂˰ڇ of Weibull distribution. The estimated reliability model is close to an exponential one, assuming a failure rate almost constant.The estimated reliability probabilistic model i̓˰̴̵̴̱̼̹̱͆̈́˰̲͉˰̵̶̷̹̀͂̿͂̽̾˰̱˰ڗ² test to verify that the estimated theoretical reliability mathematical model fits the the empirical distribution.

Abstract: In this work, a three-parameter Weibull methodology for fracture prediction of brittle and ductile materials is presented. The approach proposed requires previous definition of the failure criterion to be applied. The parameter estimation is achieved for proportionally and non-proportionally increasing stresses. The case of two concurrent failure types is also handled. The resulting primary failure distribution can be expressed as a function of an effective size (length, area or volume) for its subsequent application in practical design of specimens or components using FEM.

Abstract: Poly p-phenylene benzobisoxazole (PBO) fiber is a kind of organic fiber with high performance, but the properties of the interface between PBO fiber and resin are poor, which limit its application in the field of composite materials. Therefore, the surface modification methods were employed to enhance the interface properties, which could damage the fiber. This article assessed the influence of plasma modification, γ-ray irradiation, coupling agent, acid treatment and combined treatments on the strength of PBO fiber filament, and investigated its tensile strength with Weibull analysis. Through observation of fiber surface by SEM，it can be found that some combined treatments caused less damage to PBO fiber compared to the individual treatments. This indicates that if combining the different treatments appropriately, the interface energy of PBO fiber will increase, with the excellent mechanical properties well retained

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.

Abstract: In order to study the application of Weibull distribution in cable partial discharge pattern recognition. We apply a 10kV 30m XLPE cable for this study. Then design four kinds of typical artificial defect model and analyze each of defect model’s discharge pulse signals. Finally, estimate the Weibull distribution of signals by use of the maximum likelihood method. The results show that Weibull probability distribution is similar to partial discharge amplitude distribution, the shape parameter β can be used to identify different types of discharge.

Abstract: In this work, carbon fibers were sized with three different sizing agents in order to improve the performances of carbon fibers and the interface of carbon fibers composites. The surface characteristic was investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), at the same time, the single fiber strengths and weibull distributions were also studied in order to understand the effect of different sizing agents on carbon fibers. The interlaminar shear strength (ILSS) of the composites was also measured to study the effect of fiber coatings on the interface of the composites. X-ray photoelectron spectroscopy (XPS) was also used to analyze the element composition of carbon fiber modified by different sizing agents. This investigation shows that different sizing agents could give a different composition of surface functional group for carbon fiber, which is crucial to the interfacial performance of carbon fiber composites.