Fast Precision Margin with the First-Order Reliability Method

Abstract

Competitive aerospace design requires means to eliminate excessive margin; this can be accomplished by reformulating one’s notion of margin. This paper reviews a novel framing of the problem—precision margin—and introduces a new implementation using the first-order reliability method (FORM) for fast probability integration with principled design margin. This paper demonstrates that our margin in beta (MIB) approach preserves the incentive structure of traditional approaches, can enable lower weight penalties, is computationally tractable for practical engineering problems, and is provably conservative at a user-defined confidence level. This paper demonstrates in the sizing of a cantilever beam, and in the design of a complex, multidisciplinary supersonic nozzle.