A State-of-the-Art Review on Model Reduction and Substructuring Techniques in Finite Element Model Updating for Structural Health Monitoring Applications

The model reduction technique (MRT) is an integral part of the finite element model updating (FEMU) approach to address the issue of incompleteness in measurement. It basically condenses the size of a finite element (FE) model to fit with the available responses at limited degrees of freedom. The developments in MRTs and substructure coupling for structural health monitoring (SHM) applications have been enormous. The MRTs are partly discussed in the review articles on FEMU. However, no article is dedicated explicitly to MRTs in SHM applications. Thus, a review article on MRTs will likely augment the state-of-the-art developments of MRTs in FEMU for SHM applications. This review article synthesises the growing literature on different variants of MRTs in time and frequency domains. In doing so, the fundamentals of MRT, salient modifications on the basic MRTs to ease the computational efforts and understanding of its implementation and related developments are presented first. Further, the developments of various substructure coupling techniques used to reduce the order of large FE models are presented. The authors’ recently proposed improved MRTs are also briefly presented. Finally, the prospects and challenges in MRT and substructuring techniques are critically discussed. The review, in general, reveals that the developments in MRTs are gaining importance due to their excellent capability of handling incomplete measurements, indicating the relevance of reviewing the subject from time to time to update the latest developments.