Reliability block diagram (RBD) and fault tree analysis (FTA) approaches for estimation of system reliability and availability – a case study

Abstract

PurposeIn the present worldwide situation, the survival of a business is a major crucial aspect. The business cannot be succeeded unless it produces the anticipated production levels. Achievement of this can be possible only by maintaining the equipment into an adequate level. Load-Haul-Dumpers (LHDs), as the main workhorse and massive transporting machines, are highly utilized in underground mining operations. Despite the usage of LHDs, these are prone to the uneven and unexpected occurrence of potential failures. These are causes to minimize the production and productivity of capital intensive equipment. To get a good profitability index, it is very necessary to have the required levels of equipment reliability and availability. Estimation of reliabilities and availabilities play a critical role in the performance evaluation of equipment.Design/methodology/approachBy keeping the significance of the present research work in view in this research paper one of the well appropriate techniques such as fault tree analysis (FTA) was utilized to assess the reliability of the LHD system based on the function flow diagram. Best fit distribution of data sets were made by the utilization of Kolmogorov–Smirnov (K-S) test. Parametric estimation of theoretical probability distributions was done by utilizing the maximum likelihood estimation (MLE). Failure rate of each LHD system has computed based on the best fit results from “Isograph Reliability Workbench 13.0”. Reliability configuration of each LHD system has modeled using reliability block diagram (RBD), as well as the FTA.FindingsIndependent and identical distribution (IID) assumption of data sets was validated through statistic U-test (Chi Squared test). On the basis of test results, the data sets are in accordance with IID assumption. Therefore renewal process approach has been utilized for further investigation. Allocations of best fit distribution of data sets were made by the utilization ofK-S test. Parametric estimation of theoretical probability distributions was made by utilizing maximum likelihood estimation (MLE) method. Reliability of each individual subsystem has been computed according to the best fit distribution. The deductive method called RBD was utilized to investigate the given system reliability by analyzing with graphical representations of logic system and observed highest percentage of reliability as 69.44% (LH29). FTA has been utilized to investigate the availability percentage of a system and observed highest percentage value as 79.51% (LH29). This technique also helps to identify the most critical parts/cut sets by using Fussell-Vesely (F-V) importance measure.Research limitations/implicationsAs the reliability analysis is one of the complex techniques, it requires strategic decision-making knowledge for the selection of methodology to be used. As the present case study was from a public sector company, operating under financial constraints the conclusions/findings may not be universally applicable.Originality/valueThe present study throws light on this equipment that need a tailored maintenance schedules, partly due to the peculiar mining conditions, under which they operate. This analysis provides the information on several aspects such as present working condition of the machines, occurrence of various potential failure modes, influence of failure modes on its performance and reliable life aspects etc. Also, these investigations asses the forecasting of necessary managerial practices or control measures like possible design modifications and replacement actions of components to ensure the required levels of availability and utilization of the equipment. Both qualitative and quantitative analysis of FTA has been performed to determine the minimal/most influencing cut sets of the system and to estimate overall system availability within the work environment. Based on the computed results reasons for performance drop of each machine was identified and suitable recommendations were suggested to improve the performance of capital intensive systems.

Reliability degradation prediction of photovoltaic modules based on dependability methods

“…This is the consequence that inevitably leads to the PV modules malfunction. For this purpose, the PV modules malfunction analysis is also carried out using the Fault Tree Analysis (FTA) method, which is widely used for this analysis (Jakkula et al , 2021; Spreafico et al , 2017).…”

“…This is the consequence that inevitably leads to the PV modules malfunction. For this purpose, the PV modules malfunction analysis is also carried out using the Fault Tree Analysis (FTA) method, which is widely used for this analysis (Jakkula et al, 2021;Spreafico et al, 2017). The advantage of dysfunctional analysis using the FTA method is to set, in the form of a tree structure, the causes of PV module degradation and the parameters influencing its degradation.…”

Reliability analysis of complex electromechanical systems: State of the art, challenges, and prospects

“…RBDs have been used in offshore oil and gas development, 85 power systems, 86 and other fields. 87 Unfortunately, they are less suitable for describing logical relationships in complex systems. They can be used only to conduct static analyses of system reliability but cannot fully capture the dependencies and dynamic behaviors of large complex systems.…”

“…The calculation method is simple and fast. RBDs have been used in offshore oil and gas development, 85 power systems, 86 and other fields 87 . Unfortunately, they are less suitable for describing logical relationships in complex systems.…”

Bayesian estimate of system availability for consecutive k-out-of-n:F system

“…Performance of system based on reliability availability measures are discussed [7]- [9]. Rudkovsky and Mikhailov [10] constructed an efficient algorithm to estimate steady-state availability.…”