A New RPN Evaluation Methodology for Product Design Based on QFD, Entropy Weight and Grey Relational Analysis

Traditional method for evaluating RPN in FMEA only considers failure model’s occurrence (O), severity (S) and detection difficulty (D) without taking customer requirements into account, which would lead to design defects. To solve this problem, a new RPN comprehensive evaluation model that combines QFD, Entropy Weight and Grey Relational Analysis is constructed. First, QFD is applied to calculate the importance of technical characteristics failure models (FMI). Next, O、S、D and FMI are taken as four evaluation criteria. Then entropy weights of four indicators are computed and grey relational evaluation is conducted to calculate RPN. In the end, a practical case in an aerospace software designing will be shown.