Adjoint-Based System Identification of Large-Scale Structures

The Focus Group “Adjoint-Based System Identification of Large-Scale Structures” involves Hans Fischer Senior Fellow Prof. Rainald Loehner (George Mason University) and his host Prof. Kai-Uwe Bletzinger (Structural Analysis, TUM School of Engineering and Design).

Given the increased loads due to climate change, the aging of structures, the advances in sensor technology and the development of digital twins a very fundamental question that needs to be answered is: given measurements, can we pinpoint the location of weaknesses in structures ? The consequences of being able to accomplish this are many: one could immediately and continuously assess the health of civil engineering structures during normal loads and extreme loads, the decision process of treating aging structures (demolish, upgrade, keep as is) would be much more objective, being able to keep some aging structures operating longer would be less of a burden on the environment and reduce carbon footprint, and overall safety would be improved.

The aim of the proposed work is to develop novel mathematical tools and numerical methods to pinpoint the location of weaknesses in structures given force and displacement/ strain measurements. This will be achieved via

a) the development and use of adjoint-based solver theory and implementation;
b) the extension of the adjoint procedures to general finite element grids and all finite element types of interest;
c) scalable optimization techniques,
d) extension to optimization under uncertainty (sensor errors), and
e) deep neural nets to detect sensors that have failed or have systematic errors.

With the techniques developed, the question of the distribution (placement, number, type) of sensors will be based on a solid mathematical foundation and general practice guidelines will be possible. These techniques will be of fundamental importance for digital twins that are not only comprised of CAD data, but also a much richer information base such as structural models and sensors. 

Prof. Loehner holds a TUM-IAS Hans Fischer Senior Fellowship funded by Siemens AG.