Towards a Rapid and Cost-Effective Estimation of Fluid–Structure Interaction in Blast-Loaded Plates

Fluid–structure interaction (FSI) effects may significantly influence the dynamic response of blast-loaded structures, particularly in lightweight configurations where the structural motion modifies the pressure loading. Despite their relevance, FSI phenomena are often neglected in engineering practice, mainly due to the computational cost of fully coupled simulations and the lack of simple predictive tools. This study presents a semi-analytical framework for estimating FSI effects in free-standing blast-loaded plates. The framework relies on one-dimensional theories accounting for non-linear gas compressibility and includes both coupled and uncoupled formulations. Their comparison provides a direct quantification of the FSI contribution to the structural response. The framework was applied to two case studies from the literature, involving different blast intensities and plate areal masses. They were selected to highlight conditions in which the reflected pressure exhibits significant temporal decay while the plate is in motion, indicating relevant FSI effects. In both cases, the coupled formulation achieves excellent agreement with the observed reference data, whereas the uncoupled solution overestimates the plate velocity. These results validate the governing equations of the coupled formulation and demonstrate that they can be reliably applied to blast-loading scenarios characterised by time-decaying pressure profiles. Thus, unlike other methods in the literature, the framework extends beyond simplified loading assumptions and offers a robust basis for rapid and cost-effective estimation of FSI effects in blast-loaded plates.