Stress Field Reconstruction Method for Cargo Hold Structures of Large Ore Carriers under Combined Global-Local Loads

Objectives The discontinuity of the large-opening structure and the non-uniformity of the high-density cargo distribution of a large-scale ore carrier bring great challenges to the hull structural safety. In order to enhance the perception and adaptability of the structural health monitoring system for the global structural safety status of the ore carrier, a real-time reconstruction method of the hull stress field under the joint action of the general-local loads is proposed. Methods The refined finite element model of the cargo hold section of a large ore carrier is selected as the research object. By comprehensively considering conditions involving combined global-local and time-varying-static loads, a monitoring point arrangement scheme and a unit load basis are constructed based on load patterns and structural response characteristics. Leveraging the principle of multi-source load superposition and limited measurement data, the real-time reconstruction of the structural stress field in the cargo hold section is achieved. Furthermore, the influence of dynamic load amplitude and periodic characteristics on the accuracy of stress field reconstruction is investigated. Results The proposed reconstruction method demonstrates good predictive accuracy under typical wave conditions, with over 97% of the reconstructed data points exhibiting a relative error rate below 5%, while the maximum relative error remains around 10%. The reconstruction error increases with higher load amplitudes and shorter load periods, with the variation in load period having a more pronounced influence on the reconstruction results. Within the standard design limits, the maximum absolute error of this method does not exceed 6 MPa, indicating its potential to meet practical engineering requirements to a certain extent. Conclusions The proposed methodology demonstrates good engineering applicability for structural stress field reconstruction in large ore carriers, and it can effectively support hull structural health monitoring and residual life assessment.