Papers by Keyword: Weibull

Abstract: Pineapple leave fiber (PALF) can be considered as one of the green materials to the industries, which is the potential to replace the non-renewable synthetic fiber. However, the high disparity in the mechanical properties of PALF becomes an issue in structural composite design. Hence, improved Weibull distribution is utilised to quantify the tensile strength variation of PALF in various gauge lengths. The single fiber tensile test was performed after the fiber surface treatment and fiber diameter scanning. The predicted PALF strength by applying the improved Weibull distribution incorporating with conical frustum model is well compromised with experimental data compared to the traditional Weibull model.

Abstract: This paper presents a study of the monthly variability of wind energy potential at several heights and an investigation of the best fitting commercial wind turbine in the Cotonou coast (Benin Republic). The monthly Weibull parameters are calculated at 10 m and extrapolated at 30 and 50 m heights. The monthly Weibull wind power density and the wind speed carrying maximum energy are calculated at 10, 30 and 50 m. We showed that wind resource in the Cotonou coast is favorable for wind energy production at 30 and 50 m heights. The capacity factor of selected commercial wind turbines is calculated to investigate the best fitting wind turbine in the Cotonou coast. It turns out that Polaris 19-50 is the best fitting wind turbine in the selected turbines with a mean capacity factor of 0.49.

Abstract: This paper presents a wind energy assessment for a resort island in the South China Sea that has a seasonal climate contributed by the monsoon seasons. The resort island selected for this study is Tioman, as it denotes the typical energy requirements of most resort islands in the South China Sea. The island depends primarily on diesel-fuel for electricity generation. However, diesel is subjected to expensive and unpredictable market values, high operation and maintenance costs, and poses environmental threats. Therefore, the potential for wind energy conversion system development is conducted in order to reduce the island’s diesel fuel dependency. The study starts with energy auditing and meteorological data collection. Subsequently, the wind energy potential is evaluated using Weibull distribution function. The results indicate that the wind speed vary according to seasons, where higher wind power can be generated during the northeast monsoon season than any other seasons.

Abstract: Two-parameter Weibull-Distributing estimation method is presented to assess the life and the reliability of the axle box spring in the Electric Multiple Units (EMU) bogie. It provides a practical method for quantitative assessment of the reliability. This method can be verified by the operation of the new EMU running in the future. Meanwhile, as it is based on the actual operation data, the conclusion of the assessment is very valuable to the EMU safety.

Abstract: A method is introduced to process the failure data of 12 sets of machining centers for modelling and analyzing their reliability. In this method, Matlab is applied to fit the failure data for getting a hypothesis that their time between failures obey weibull distribution. Then, MLE (maximum likelihood method) is used to estimate parameters of distribution model of the time between failure, and the K-S test is employed to test the above hypothesis for proving that time between failures of machining center obey weibull distribution. Finally, the analysis of their common failures and corresponding improvements are done, which provide the theoretical basis for improvement of reliability of machining center and are greatly valuable in engineering.

Abstract: Application of fused deposition modelling components are gaining popularity in functional application. In order to use these components directly for functional application, reliability in service has to be acheived. A Reliability analysis was caried out on components manufactured by fused deposition modelling. A standard test specimen as per ASTM was prepared and tested for fatigue cycles to failure. Bending stress was calculated prior to the fatigue testing by varying the slice thickness. Fatigue test was carried out with differnt loading condition. Fatigue test results were subjected to weibull analysis to determine the reliability of FDM components. The Weibull design values were calculated and Weibull distribution plot for failure was plotted and analyzed. Estimation of reliabilty for different cycles to failure was also found out.

Abstract: Selective laser sintered metallic specimens were tested for fatigue cycles to failure and analyzed for reliability. In this study, Taguchi’s experimental techniques were used to develop a modified L9 orthogonal array. Three different process parameters, laser power, scan spacing and slice thickness were selected for manufacturing the components. Fatigue testing was carried out as per ASTM standards and relationship of the process parameters on the fatigue cycles to failure was investigated. ANOVA method was used to find the dependence of the process parameters and to find the influence of main process parameter on fatigue cycles to failure of the specimens. Laser power was found to be the most significant factor compared to scan speed and slice thickness. Two-parameter Weibull method was used for the reliability studies by which reliability was estimated for different cycles to failure.

Abstract: To better study the mechanical behavior of red ceramic, the samples were degraded in salt spray equipment and exposed in environment. The salt spray equipment subjects the samples to conditions found by the sea, through the mix solutions of sodium chloride. The ceramic samples were prepared with up to 10% by mass of ornamental rock waste to dry and pressed into rectangular mold of steel. The materials were fired at temperatures of 650°C, 750°C and 850°C. After 90 days of degradation natural and 45 days in salt spray, ware analyzed the properties of ceramic material. The results of mechanical strength were compared using the Weibull distribution, before and after the degradation. Note that the material with ornamental rock waste raised the mechanical strength and didnt significantly changes the material properties after degradation.

Abstract: The ceramic sector is important to the economy in Rio Grande do Norte, Brazil. Overall, however, the manufacturing process is imperfect; leading to inappropriate use of raw materials, waste of energy, environmental degradation, nonconformity to the Brazilian and international standards, etc. So, its crucial improves the produced bricks. This work aims to contribute to quality control of the ceramic industry, raising the values of physical properties of their products. The main parameters that influence these values were determined by Weibull statistics. Ceramics were studied by measuring porosity, water absorption, linear shrinkage, bulk density and mechanical strength. Mechanical strength test data resulted in Weibull distributions. The Weibull statistic parameter was calculated to best evaluations of ceramic quality. The results support our initial considerations about current stands of low quality of ceramic products from Rio Grande do Norte and underline the importance of testing and improving these products.

Abstract: Reliability of equipment of the oil and gas industry is vital, whereas on pipeline transmission system, decreasing the integrity of the pipeline is generally caused by corrosion. Failure that occurs due to corrosion deterioration influenced by the environment within a certain time, and has exceeded the nominal thickness of the pipe so there is a failure. This study used the reliability analysis approach based on modeling corrosion degradation ratio that is determined by the amount of the corrosion rate externally and internally. Using the Weibull probabilistic distribution method, results that the reliability of pipeline will decrease with increasing lifetime. It was identified that internal corrosion has a major contribution to the remaining life of pipeline. From the calculation results obtained by external corrosion has the greatest reliability over 60 years, followed by internal corrosion less than 30 years and the least is by cumulative corrosion which is less than 20 years. From the value of reliability, it can be known probability of failure (POF) which is the anti reliability.