Papers by Keyword: Weibull Distribution

Abstract: In this paper, the parameter estimation problem of products which are mutually independent and whose life belongs to two parameters Weibull distribution in fixed-time censoring experiment is discussed. And the rank of failure data is corrected by average rank time method, when the censoring experiments appeared. It is found that the method not only achieves the same effect for likelihood function theory, but also has the characters of high precision, simple process, no programming calculation, when model optimization is done by correlation index method. Finally, take field test data of a machine tool as an example to introduce the specific application process of this method, in order to verify the effectiveness and practical applicability.

Abstract: The life distribution model and accelerated life testing methods of the disc magazine and manipulator were discussed. The small sample determination of truncation test was performed to QY011 and a batch of test data under the accelerated stress at the selection of vibration as the accelerated stress have been obtained. The reliability life index under certain stress level was analyzed through established the accelerated probability weighted Weibull model and inversed power law model for acceleration model. According to the acceleration model and statistical analysis of test data, the QY011 reliability life level of QY011 disc magazine and manipulator under the normal working conditions were calculated.

Abstract: Shiploaders are used to load bulk material onto vessels. They can experience a large number of loading cycles during their design life. As a consequence, fatigue damage is an important consideration when assessing the useful life of an existing shiploader. This paper presents the results of the fatigue assessment of an existing shiploader. The shiploader is used to load coal onto bulk carriers; it is over 30 years old and the operator wishes to continue to use the facility for at least another 25 years. The results from the fatigue assessment form part of the decision making process for replacement or refurbishment of the shiploader. This assessment includes data from finite element analysis, strain gauging and measurements from on-board monitoring equipment. The results from the fatigue assessment were used to calculate the probability of fatigue damage for continued use.

Abstract: Reliability growth assessment is an important part of the reliability growth management. According to the characteristic that the lifetime of electromechanical product obeys the Weibull distribution, the thesis provides a monotonous constraint model of reliability growth of Weibull distribution, including complete Samples and censored samples. The method proposed in this paper has been verified by actual data, and has good adaptability. The comprehensive evaluation results of MTBF are higher than those got through only utilizing the test data of the last stage.Background Information

Abstract: A statistics method was carried out to characterize the fatigue strength distribution of GF/PP composites. Based on the stress of yarn bundles, the Weibull distribution parameters were determined. Also, we had presented an expression of interfacial shear stress between yarn tows and matrix. A Monte-Carlo simulation with 2D shear-lag equation had been used to analyze the tensile strength and simulate the failure process of unidirectional stretch of composites. Good agreements were obtained between the predicted results and experimental data.

Abstract: Three kinds of methods commonly used for estimating Weibull parameters were fitted to a collection of wind speed data at 10 m above ground level for the year of 2009 to determine the best distribution function which describes the wind speed variation at Msila, Algeria site for wind energy. Three methods used the coefficient of determination R2, root mean square error RMSE and Chi-Square χ2 were compared with failure analysis. According to the results of failure analysis the moment method has better results than graphic method and power density method. The wind power density calculated from moment method shows a good approximation to estimate the power density. So the Weibull distribution using the moment method adequately fit the data and it is suitable for modeling the wind speed distribution in Msila province of Algeria.

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.

Abstract: The reliability assessment of power system components is the key to power system safe and reliable operation. According to the record of actual operation of power system components characteristics, a practical method of reliability evaluation for fault date which is missing components is introduced in this paper. The method is based on Weibull distribution model. It is also a calculation and solving methods of reliability evaluation fault system of missing data components. The system mainly includes sample selection of data, parameter calculation, model checking and failure rate curve drawing. So the transformer as an example, verify the effectiveness of this method. In addition the paper analyses the influencing factors in the transformer reliability, such as voltage grade, manufacturer and product types. In a word, this model provides a systematic and effective method for the practical application of the reliability evaluation of the electrical components.

Abstract: Through the fatigue experiments of glass fiber reinforced concrete (GFRC) specimens with 0%0.6%0.8% and 1% glass fiber volume fraction, the fatigue-lives of GFRC at various stress levels were obtained. The results indicate that the statistical distribution of fatigue-life of GFRC is in agreement with the two-parameter Weibull distribution. According to the statistical analysis of fatigue-life,the study shows the fatigue life of GFRC follows both the two-parameter Weibull distribution and three-parameter Weibull distribution, but three-parameter Weibull distribution is more suitable for expressing the law. Besides, the S-N curves and P-S-N curves which can be used to determine the life of GFRC under constant amplitude fatigue load were obtained.The results indicate that GFRC has distinguished anti-fatigue property.

Abstract: Beam bending fatigue test was done by MTS810 using stress control mode, the double logarithm fatigue equations and Weibull fatigue equations of three types of modified asphalt mixtures for intermediate course under different design method are gained. Good performance of the modified asphalt mix design programs are choose to use in the Northeast region to explore the modified asphalt mix design method for the use of intermediate course through a comparative study of 3 types of modified asphalt mixture fatigue performance.