Primary failure mode and effects analysis with function-motion-action hierarchy structure for mechatronic systems

Abstract Failure mode and effects analysis (FMEA) is a systematic bottom-up structured method used originally in aerospace systems then electronic systems to implement failure analysis, criticality analysis, and failure clearance. With its effective application, FMEA has been extended rapidly into mechatronic systems and others to improve system reliability. However, there exist different compositions, loading forms, operation modes, and failure mechanisms for diverse kinds of systems, so the formulaic extension of FMEA usually is not suitable for the actual situation of followers. In this paper, we propose a function-motion-action (FMA) hierarchy structure especially suitable for mechatronic systems, which focuses on describing and analyzing failure behaviors such as identifying failure modes, analyzing failure causes, and mapping failure effects at each system structure layer without vague and overlapping interpretations. Three risk factors namely occurrence, detection or non-detection, and severity are both defined for each of failure behaviors at each system structure layer, in which the occurrence describes all failure behaviors and the severity is reliant on the condition of the detection and non-detection about all failure behaviors. A primary risk calculation model using quantitative risk data is established to garner the risk level of each failure, based on which multiple and specific risk levels of each failure are explained when considering different levels of failure effects and different combinations of control methods.