Faculty Publications
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Item Failure rate and reliability of the KOMATSU hydraulic excavator in surface limestone mine(American Institute of Physics Inc. subs@aip.org, 2018) N. S., N.S.; Choudhary, R.P.; Murthy, C.S.N.The model with failure rate function of bathtub-shaped is helpful in reliability analysis of any system and particularly in reliability associated privative maintenance. The usual Weibull distribution is, however, not capable to model the complete lifecycle of the any with a bathtub-shaped failure rate function. In this paper, failure rate and reliability analysis of the KOMATSU hydraulic excavator/shovel in surface mine is presented and also to improve the reliability and decrease the failure rate of each subsystem of the shovel based on the preventive maintenance. The model of the bathtub-shaped for shovel can also be seen as a simplification of the Weibull distribution. © 2018 Author(s).Item Evolution of the Probability Distribution Function of Shovel – Dumper Combination in Opencast Coal Mine Using ANN and RWB(Springer Nature, 2020) N. S., N.S.; Choudhary, R.P.; Murthy, C.S.N.This article presents a new analytic calculation for the shovel – dumper combination in opencast coal mine evolution of the one and two galaxy probability distribution function (PDF). To develop a nonparametric PDF for a combination of shovel and dumper in a opencast coal mine, the historical breakdown data such as time between failure (TBF) of a shovel and dumpers were collected from the mine. Based on the collected TBF, Weibull parameters such as the shape parameter (β), scale parameter (η) and location parameter (γ) were calculated under the K-S test (Kolmogorov–Smirnov test). A Weibull distribution model has been developed to obtain the one and two galaxy probability distribution function (PDF) for a collected failure data of shovel-dumper system using Reliability Isograph Workbench (RWB). Also, Artificial Neural Network (ANN) model has been developed to predict the PDF for the same shovel-dumper system and compared with the actual obtained value of Reliability Isograph Workbench (RWB). It was found that the values of RMSE and R2 were 0.00068 & 0.9465 for PDF. The statistical results showed that the proposed Reliability Isograph Workbench and ANN model successfully predicts PDF for the shovel-dumper system. © 2020, Springer Nature Switzerland AG.Item Flexural fatigue analysis of steel fibre reinforced concrete(2012) Girish, M.G.; Chandrashekar, A.; Ravi Shankar, A.U.This paper presents the experimental investigation carried on Steel Fiber Reinforced Concrete (SFRC) subjected to repeated loading. The SFRC beam specimen of size 500mm × 100mm × 100mm containing mixed steel fibers of size 50mm × 2mm × 0.6mm and 0.5mm?× 30mm in different proportions were tested under two point flexural fatigue load at a frequency of 2Hz at various stress levels. The readings obtained from the flexural fatigue test were used to plot S-N diagram and also to perform statistical analysis using two parameter Weibull distributions. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.Item Investigations on Alkali-Activated Slag/Fly Ash Concrete with steel slag coarse aggregate for pavement structures(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2017) Palankar, N.; Ravi Shankar, A.U.; Mithun, B.M.The present investigation is conducted to evaluate the effect of steel slag coarse aggregates on mechanical properties and fatigue behaviour of Alkali-Activated Slag Fly Ash Concrete (AASFC) mixes. AASFC mixes were prepared with steel slag coarse aggregates by replacing natural coarse aggregates at various replacement levels (0, 25, 50, 75 and 100% by volume). Various mechanical properties and fatigue performance were tested and compared with conventional Portland concrete. The incorporation of steel slag aggregates resulted in decrease in mechanical strength of AASFC mixes. The fatigue lives of AASFC mixes containing steel slag were found to be lower than AASFC with natural coarse aggregates. Two-parameter Weibull distribution was used for statistical analysis of fatigue data and it was observed that the fatigue data of concrete mixes can be approximately modelled using Weibull distribution. Steel slag aggregates reported acceptable performance in AASFC mixes for its use in pavement quality concrete. © 2015 Informa UK Limited, trading as Taylor & Francis Group.Item Reliability analysis and failure rate evaluation of load haul dump machines using Weibull distribution analysis(International Information and Engineering Technology Association info@iieta.org, 2018) Balaraju, R.J.; Govinda, R.M.; Murthy, C.S.N.Improvement of multifaceted system quality requires a group of complex design modifications. An expanding complexity of system is potentially prone to increase in the failure frequency. Continuous and random occurrence of failures in a system could be the main cause for performance drop of machinery. Theoritical probability distribution is one of the techniques used to estimate the lifetime of a system and its sub-systems with several failure considerations. One of the most extensively used statistical approaches for reliability estimation is a Weibull distribution. In the present paper a three-parameter Weibull distribution approach was adopted to analyze the data sets of Load-Haul-Dumper (LHD) in underground mines using 'Isograph Reliability Workbench 13.0' software package. The parameters were evaluated using best fit distributions and Weibull likelihood plots. Percentage reliability of each individual subsystem of LHD was estimated. Further, an attempt has been made to identify the preventive maintenance (PM) time intervals for enhancing the expected rate of reliability. © 2017 IIETA.Item Failure rate analysis of shovel and dumper in opencast limestone mine using RWB and ANN(Blue Eyes Intelligence Engineering and Sciences Publication, 2019) N. S., H.K.; Choudhary, R.P.; Murthy, C.S.N.To develop a nonparametric bathtub curve model for a shovel and dumper in an opencast limestone mine, the historical failure data such as time between failure (TBF) and failure frequency of a shovel and dumper were collected from the mine. Based on the collected TBF and failure frequency, Weibull parameters i.e., shape parameter (?), scale parameter (?)?and location parameter (?) were calculated under the K-S test (Kolmogorov–Smirnov). A Weibull distribution model has been developed to obtain the probability distribution function (PDF) and the bathtub-shaped failure rate curve for a shovel-dumper system using Reliability Isograph Workbench (RWB). Also, the Artificial Neural Network (ANN) model has been developed to predict the PDF and failure rate for the same shovel-dumper system and compared with the obtained values of Reliability Isograph Workbench. It was found that the values of RMSE and R 2 were 5.96E-5 & 0.999 for PDF and 9.23E-8 & 0.9993 for failure rate respectively. © BEIESP.Item Failure rate analysis of shovel and dumper in opencast limestone mine using RWB and ANN(Blue Eyes Intelligence Engineering and Sciences Publication, 2019) N. S., N.S.; Choudhary, R.P.; Murthy, C.S.N.To develop a nonparametric bathtub curve model for a shovel and dumper in an opencast limestone mine, the historical failure data such as time between failure (TBF) and failure frequency of a shovel and dumper were collected from the mine. Based on the collected TBF and failure frequency, Weibull parameters i.e., shape parameter (?), scale parameter (?) and location parameter (?) were calculated under the K-S test (Kolmogorov–Smirnov). A Weibull distribution model has been developed to obtain the probability distribution function (PDF) and the bathtub-shaped failure rate curve for a shovel-dumper system using Reliability Isograph Workbench (RWB). Also, the Artificial Neural Network (ANN) model has been developed to predict the PDF and failure rate for the same shovel-dumper system and compared with the obtained values of Reliability Isograph Workbench. It was found that the values of RMSE and R2 were 5.96E-5 & 0.999 for PDF and 9.23E-8 & 0.9993 for failure rate respectively. © BEIESP.Item Statistical analysis of acoustic emissions generated during unconfined uniaxial compression of cementitious materials(Elsevier Ltd, 2019) Vidya Sagar, R.; Singh, M.; Deepak, S.; Desai, P.R.The article reports a study on the ‘goodness of fit’ of Weibull and Normal (Gaussian) distributions on the compressive strength and the corresponding Acoustic Emissions (AE) of cementitious materials. An attempt has been made to understand the variation of the parameters of the Weibull distribution and the Gaussian distribution carried out on the uniaxial compressive strength data and the corresponding recorded AE parameters. The statistical analysis of ‘Damage Parameter’ based on the peak amplitude of AE signals was also carried out. It was observed that the Weibull distribution was a better fit than Gaussian distribution for compressive strength and damage parameter. But in the case of AE parameters, Gaussian distribution was a better fit. The results obtained from this statistical study may be an addition to the existing knowledge on the statistical approach of AE associated with cementitious materials. A statistical approach may be suitable in predicting the data values without conducting further experiments. The results may be useful to understand the variation of physical properties such as homogeneity and ductility with the variation of compressive strength of cementitious materials and its corresponding AE parameters. © 2019Item Model based reliability analysis of shovel–dumper system’s mechanical failures used in the surface coal mine: a case study(Taylor and Francis Ltd., 2020) N. S., N.S.; Choudhary, R.P.; Murthy, C.S.N.In a surface coal mine, efficient usage of shovels and dumpers should be most reliable and available to reach their production target. Keeping this in mind, this study was carried out at a surface coal mine, which is located at Open Cast-I, The SCCL, Kothagudem area, Telangana. The mechanical failure data such as time between failures (TBF) and time to repair (TTR) of each sub-system of a shovel-dumper system were collected and analysed statistically and graphically for reliability and availability. Graphical methods such as trend test and series correlation test and Chi-squared test were used to validate the independent, identically distribution of mean time between failures and mean and time to repair for the same a shovel and dumpers. Statistically, the Weibull distribution is selected as it was found the best-fit distribution by the Kolmogorov-Smirnov (K-S) test using Isograph Reliability Workbench. In K-S test, it was found that shovel KS1 has reliability of 0.2682 and dumpers BD1, BD2, KD2 and KD4 had reliability of 0.3731, 0.2850, 0.2897 and 0.2962, respectively for the 1 year of working hours. Also, calculated reliability- based time interval for preventive maintenance to achieve 70, 80 and 90%, respectively of reliability for same shovel-dumper system. © 2020 Safety and Reliability Society.Item Bond shear strength of Al2O3 nanoparticles reinforced 2220-capacitor/SAC305 solder interconnects reflowed on bare and Ni-coated copper substrate(Springer, 2021) Tikale, S.; Prabhu, K.N.The influence of Al2O3 nanoparticles addition in trace amounts and electroless Ni–P substrate coating on the microstructure development and bond shear strength of Sn-3.0Ag–0.5Cu (SAC305) solder joint were investigated. The performance and reliability of the 2220-capacitor joints with Al2O3 nanoparticle reinforced nanocomposites reflowed on Cu and Ni–P coated substrate were analyzed under varying high-temperature environments. The addition of nanoparticles enhanced the wettability and microhardness of the solder and considerably refined the joint microstructure. The dispersion and adsorption of Al2O3 nanoparticles resulted in the suppression of intermetallic (IMC) growth at the interface and refinement of the ?-Sn grains as well as IMC precipitates into the matrix. The Ni–P coating on the substrate significantly retarded the IMC growth kinetics resulting in the formation of a thin and uniform IMC layer at the joint interface. The thermal stability and performance of the joint under high-temperature environments were enhanced due to the Ni–P coating on the substrate. Compared to the unreinforced SAC305 solder joint with bare Cu substrate, joints with SAC305 + 0.05Al2O3 composite showed about 17% higher shear strength with bare Cu substrate and about 27% higher strength with Ni–P coated substrate. The Weibull distribution analysis indicates a significant improvement in joint reliability of the 2220-capacitor/SAC305 solder assembly using SAC305 + 0.05Al2O3 nanocomposite and Ni-coated substrate. The ANOVA study suggests that the solder joint performance majorly depends on the operating environment, solder composition, and the substrate finish. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.