Ph.D. Proposal Presentation by Hae-Jin Choi
Monday, April 26, 2004

( Dr. Farrokh Mistree, Chair)

"A Robust Design Method under Model and Propagated Uncertainty"


Uncertainty in a model estimating performance of a system is one of the important factors to be considered in an engineering system design because engineers usually employ limited number of sampled data or a simplified model rather than a complex model in order to reduce analysis lead-time or due to lack of knowledge. The uncertainty is propagated and accumulated in a series of design tasks so that it could make a final estimated value much deviated from the true one. Many studies have been done to design a system to be robust and reliable from the unexpected effect of the uncertainty. However, the studies have not considered embedded uncertainty which is difficult to be parameterized in a system, and it is common in a complex system design, such as materials design.

In this study, a new approach for robust multi-scale materials design will be developed that will facilitate search for robust materials design solution against external uncertainty, model uncertainty, and those propagation along multiple length-scaled models. Several accomplishments will make this approach possible, including (1) a robust design exploration method incorporated with the ‘Error Margin Indices’ concept, (2) a method for formulation of uncertainty boundaries in a model with fewer experimental data extending a model calibration technique, (3) a graphical grammar for representing uncertainty propagation within robust design network, and (4) a method for mitigating propagated uncertainty in hierarchical and sequential design tasks. Potential application could be extended to general multiple robust designs with external and model uncertainty.