FMEA - A DIGRAP AND MATRIX APPROACH

This paper presents a method for failure mode and effects analysis (FMEA) of mechanical and hydraulic systems based on a digraph and matrix approach. The method takes into account structural as well as functional interaction of the system. This is desirable as failures in these systems are not independent. A failure mode and effects digraph, derived from the structure of the system, models the effects of failure modes of the system and consists of nodes, subnodes and edges. For efficient computer processing, matrices are defined to represent the digraph. A function (VCM-F(me) or VPF-F(me)) characteristic of the system failure mode and effects is obtained from the matrix and this aids in the detailed analysis leading to the identification of various structural components of failure mode and effects. In addition, the number of tests for failure mode and effects are derived. An index I(fme), a measure of failure mode and effects of the system, is obtained using VPF-F(me). The methodology is applicable not only at the design stage but during the operation stage also.