Determination of Failure Rate and Assessment of Risk Priority Number in FMECA using the Fuzzy Theory and Expert System

摘要

As the Failure Mode, Effect and Criticality Analysis(FMECA) is being studied, maintenance tasks can be performed effectively through the Risk Priority Number(RPN) evaluation. This RPN provides information which includes the risk level and the priority order of maintenance tasks for components. However, if there is no sufficient historical failure data, the historical failure data from other sources can be used and apply this data to our system. And if we use historical data from other sources without any process, there will be concomitant problems according to a discord of each system characteristic, a difference between the present and the date of failure data and etc. In this paper, a new methodology is proposed to model the failure rate as a fuzzy function to settle these problems. Taking advantage of this result, the RPN can be calculated by using the fuzzy operation. The proposed method is applied to the substation system.