Failure mode and effects analysis using fuzzy method and grey theory

Traditional failure mode and effects analysis (FMEA) determines the risk priority number by finding the multiplication of factor scores that are converted from the probability or degree of problem occurrence without considering the relative importance of factors. This study applies fuzzy theory to eliminate the conversion debate by directly evaluating the linguistic assessment of factors, and uses grey theory to obtain risk priority number by assigning relative weighting coefficient without any utility function. Results of the illustrative example show that concurrent application of fuzzy method and grey theory can solve the problems that have arisen from conventional FMEA, and can efficiently discover the potential failure modes and effects. Indicates that, as a result, the stability of product and process can be assured.