Expected productivity-based risk analysis in conceptual design

To be effectively used in design decisions, it is important to bring risk into the design process as a quantitative parameter that engineers can both understand and trade. One parameter that is often used when making design decisions is the productivity of a design. If instead of only the nominal value, it were possible to examine the expected value of the productivity metric, taking into account failures and risk items, the concept of risk could be brought into the design process in a very quantitative and tradable way. While the expected productivity is easy to calculate for a simple system, it is more complex if the system has a path-dependent productivity function. An approach has been developed to model the expected productivity of systems with path-dependent productivities, in an accurate and efficient manner. This approach has been tested against Monte Carlo simulations with excellent results. This paper discusses the need for the new modeling methodology, the details of the methodology that has been developed, and an example of how to use expected productivity in a trade study for a real mission, the Terrestrial Planet Finder Interferometer.