A Software Tool Subjecting Component Designs to System-Level Reliability Constraints

A software tool entitled PRODAF (Probabilistic Design and Analysis Framework) is described that demonstrates a practical, multidisciplinary, design-for-reliability methodology for aerospace systems. PRODAF allows system-level reliability constraints to impact component-level designs. The method interfaces user-selected, physics-based deterministic modeling codes with a Fast Probability Integration code to obtain high-fidelity probabilistic component failure rate data. The computed component failure rates are input into a system-level probabilistic risk assessment code such as QRAS or SAPHIRE. A feedback loop from the risk assessment tool to the analysis/design tools enables the system-level reliability constraint to affect the component design. Accuracy measures of the probability calculations (confidence intervals) are provided to account for uncertainties in the uncertainty parameters. Design variable optimization is accelerated through the use of adaptive response surface modeling. On-screen results are presented graphically in terms of CDF/PDF plots and sensitivity charts. The software tool is currently in development.