Abstract

This report discusses fundamental principles of uncertainty propagation (UP) for computational engineering, with an emphasis on aircraft design. The core issues that this report addresses is the long-standing tradition for the use of deterministic design techniques used in aerospace engineering. Uncertainty quantification and, in particular, propagation is not widely adopted concept in the aerospace sector. Key reasons for this are the perceived computational overhead, misunderstanding of critical concepts, and underappreciation of the potential of UP radically new designs. The report is built on the basis of clear separation of the two main types of uncertainty recognised by engineers today, aleatory and epistemic uncertainty. One of the goals of the text is to instruct the engineer in how to best utilise the flexibility offered by this separation and what techniques are available to them. The entire monograph is oriented towards practical issues such as code accessibility, types, and amount of information accessible to the engineer. The text introduces the main types of uncertain numbers likely to be encountered by aircraft designers and engineers and demonstrate how they can all be efficiently treated with interval-based methods. These methods achieve their best performance when applied intrusively, that is when they are built in the model. Despite of this, engineers are most often faced with closed, black-box codes which necessitates using alternative approaches to UP. This is a main vein in the report. This text is the third part of the DAWS series of reports on uncertainty quantification. The first of the series, which underpins many aspects discussed in the present report can be found here. The second report, discussing the topics of verification, validation and predictive capability estimation can be found here. The remaining two reports will focus on sensitivity analysis and calibration.

This is v. 1.1.

Changes from the previous version:

• Updated abstract with information and links to reflect new reports and activities.

• Introduced version information.

• Corrected mistakes in Section 1.7 about the order of reports in the DAWS series.

If you need access to previous versions, please email p.hristov@liv.ac.uk