Ultrasonic Guided Waves (UGWs) are particularly suited for monitoring applications as their high frequency allows them to interact with small defects while traveling long distances. For defect localization in plate structures, Lamb waves are generated and exploited in the UGW sense. While data-driven methods, exclusively driven from the collected time series have proven adept for various damage identification tasks, a more refined characterization calls for additional use of physics-based models. In this work, we demonstrate efficient fusion of UGW data with numerical models of plate structures, which are obtained from high-fidelity spectral element simulations. A major bottleneck associated with such a hybrid modeling scheme lies in the excessive computational cost associated with simulations of high–frequency Lamb waves through plate structures. This is due to their short wavelength and short period, which demands a fine discretization in both space and time. To avoid repeated evaluations of prohibitively expensive computational models, model order reduction methods or surrogates can be adopted. A surrogate model should be based on mechanical information, to reduce the amount of training data required. For practical reasons, surrogate models should further be flexible, allowing for assimilation of multiple defect locations, as well as the simulation of more complex geometrical features, such as rivet holes or boundaries. We show steps toward construction of such a surrogate, which draws its construct from the concept of Frequency Response Functions (FRFs), or in other words, the representation of a system in the frequency domain.
|