Advanced failure modes and effects analysis: A method for predicting and evaluating failures in products and processes.

摘要

Failure Modes and Effects Analysis (FMEA) is a technique to help anticipate, evaluate, and reduce risk of failures in a design (or process) before they occur. Although FMEA has worldwide recognition across many industries, there are documented limitations to the technique. For example, the method has very little structure when used during the early stages of design, and many failures go undetected until it is too late. In addition, it is difficult to interpret cause-effect failure relationships in FMEA, and the method for evaluating risk has come under some criticism. This dissertation proposes a method, Advanced FMEA, to address some of the shortcomings of the conventional approach. The purpose of Advanced FMEA is to provide a structured technique for representing and identifying a broader set of failures, especially during the early stages of design. If failures can be detected early in the design process, the cost of implementing solutions is minimal, while the impact on reliability is significant. The method offers a general approach that can be applied to conceptual designs, concurrent design of products and controls, manufacturing processes, and other business processes.; To meet these objectives, Advanced FMEA integrates several important concepts that distinguish it from conventional FMEA, including: (a) a function-state model to represent general systems, designs, processes, & controls, (b) a technique for identifying failures using the function-state model, (c) the incorporation of “failure scenarios” to represent the causal failure chain, and (d) Risk evaluation based on probability and cost. Advanced FMEA uses the function-state model to link desired functions with the components, operating environment, related systems, and control logic. The model is then analyzed systematically for failures, which are represented as “scenarios.” Failure scenarios are prioritized according to risk using probability and cost. Advanced FMEA can be applied to conceptual designs, concurrent design of products and controls, manufacturing processes, and other business processes. In addition, the new risk evaluation criteria facilitate cost-based decision making during product development. The relative merits and limitations of Advanced FMEA are demonstrated through several case studies and theoretical examples.