THE EARLY DESIGN RELIABILITY PREDICTION METHOD

The purpose of this paper is to formalize the Early Design Reliability Prediction Method (EDRPM) into a comprehensive framework, then to provide a case study using an Electrical Power System (EPS) which shows the usefulness of the methods. EDRPM has been developed to facilitate decision making in early design using quantitative reliability results [1]. Candidate components and design alternative are eliminated using justification provided by EDRPM. The output of this method is a set of design alternative that have a reliability values at or greater than a preset reliability goal. At the completion of applying EDRPM, additional metrics can be used to determine a final design. This research addresses the need for reliability methods to be moved earlier in the design process. Current methods are applicable after components have been selected. EDRPM is used during functional design, and when concepts are generated. This method also calculates functional failure rates which are applied to generate the function and component distributions. The results of the case study shows that several candidate components and design alternatives can be eliminated using EDRPM. It is demonstrated that only a subset of designs that meet the failure rate piece of the reliability goal should not be eliminated. The reliability goal is the combination of two parts; the failure rate and the probability of not exceeding the failure rate. Several of these design still have a probability of exceeding the second piece of the reliability goal given that they meet the first.