FAILURE CAUSE ANALYSIS - A STRUCTURAL APPROACH

The paper presents a methodology to analyze failure cause of a system using structural approach based on digraph and matrix method. Failure causality digraph models the failure cause considering contributing ev ents and their interaction in terms of cause-effect relation, i.e., ca usality. Failure cause function (VPF-f(c)) is obtained from the perman ent matrix, obtained from the digraph, which is characteristic of the failure cause. The procedure is useful, not only for the analysis, but also for identification, comparison, and evaluation of the failure ca use. The coefficients of similarity and dissimilarity, and identificat ion set based on these are also proposed. These are useful for compari son of two failure causes. In addition, failure cause index (I-fc) der ived from VPF-f(c) is proposed which evaluates and ranks failure cause s of the system. The method permits analysis, identification, and comp arison at design as well as operating state of the system and provides the user directions for minimizing the failure causes leading to impr ovement of the system reliability. The procedure is developed using an example of weld defects.