| Failure modes and effects analysis (FMEA) has been a standard design practice for many years. Major factors include component failure rate, type of failure, severity of failure, and likelihood of detection. FMEA can identify areas requiring increased reliability, functional redundancy, or preventive maintenance. Most of the common FMEA practices are based on MIL-STD-1629A (DoD, 1980).; Traditional FMEA usually occurs too late in the design process, because the method relies on the specification of the components that make up the device. Generally, the required component information is available only after completion of the detailed design. Any shortcomings in the design that might be identified by a FMEA can be very expensive and difficult to correct.; This work adapts the concepts of behavior modeling to the process of mechanical system design. Linking the behavior representation to a high level structural representation allows us to define failures and component misbehaviors early in the design stage. The proposed advanced failure modes and effects analysis (AFMEA) performs analyses of device behavior, reasons about conditions that depart from desired behaviors, and analyzes the results of those departures.; Two examples illustrate the proposed method; an automatic ice maker and an industrial air cooling system. The ice maker shows that our method is capable of capturing failures normally missed by existing FMEA methods. The air cooling system example demonstrates our ability to model and analyze a system in the early stages of design, and systematically determine the local effects and end effects of system failures. We also presented our method to two groups of students and asked them to perform a design task. The students demonstrated that behavior modeling, augmented with functional analysis, can aid design from the very early conceptual development stage.; One limitation of the proposed method is the difficulty of transforming aesthetic and packaging requirements into elements in the behavior model. Another concern is that simplifying the behavior model syntax might lead to decreased simulation accuracy and increased implementation challenges. Topics for further investigation include additional usability testing in a design setting, use of more sophisticated modeling and simulation techniques, methods for semi-automated failure selection, and implementation of a computer-based modeling tool. |
