A novel method for monitoring combined loads and small-scale damage in hull structures using time domain strain signal

Accurate identification of external loads and structural damage is essential for the safety and reliability of ship hulls during long-term service. To this end, this study proposes an integrated framework for identifying bending moments, torsional moments, and small-scale damage from time-domain strain signals. Specifically, the framework combines iterative load estimation with a multi-network strategy for damage identification, thereby enabling damage assessment based on the identified load information. For numerical validation, finite element analysis and CFD-FEA simulations were conducted under different load combinations, noise levels, and wave conditions. Overall, the proposed method outperformed the Influence Coefficient Method (ICM) in terms of both load-identification accuracy and robustness. Specifically, for combined bending and torsional loading, the error fluctuation range of the ICM was more than twice that of the proposed method. Consequently, the improved load-identification accuracy enhanced the subsequent damage-identification performance. Moreover, when both bending and torsional effects were considered, the multi-network strategy improved damage-identification accuracy by up to 20%. The proposed framework demonstrates potential for localized structural health monitoring of ship hulls under the investigated numerical conditions.