A fuzzy FMEA assessment of hydroelectric earth dam failure modes: A case study in Central Brazil

Abstract

The good operating practices of hydroelectric plants with earth dams recommend that continuous monitoring of the construction elements should be carried out to ensure their stability and integrity. Engineers have frequently used FMEA to assess mechanisms that can cause damage or failure of such structures because it is a self-documented and straightforward method. We adopted fuzzy approximate reasoning to mitigate the rigidity of the FMEA rating scales and to address the bias and inaccuracy inherent in subjective estimates. This paper applies linguistic variables in a two-stage assessment. In the first stage, we computed the RCI through the combined effect of Occurrence and Severity. In the second stage, we combined the RCI with Detection to compute the FIS-RPN. The failure modes, causes and effects, the rule bases for the two stages and the membership functions were obtained through in-depth interviews with a focus group composed of staff members of the Corumbá IV hydroelectric plant, located in Central Brazil. The fuzzification process assured more consistency to the RPN calculation, treated the imprecision and provided fair management value to prioritize actions and improve monitoring processes.