Objectives In pursuit of energy efficiency and enhanced performance in the cruise ship industry, the lightweight design of large cruise ship superstructures has emerged as a critical research priority. Aiming at the specific lightweight requirements of the upper decks in large cruise ship superstructures, this study proposes a novel composite sandwich panel with steel stiffeners. Designed as a replacement for conventional steel-stiffened panels, this innovative structure aims to achieve substantial weight reduction while maintaining or even improving structural strength and mechanical performance, thus contributing to the overall efficiency and competitiveness of large cruise ships.

Methods To comprehensively evaluate the axial compression ultimate strength of the proposed panel, a series of experimental and numerical studies were conducted. In the experimental phase, a meticulously designed test model with specific dimensions was fabricated. Tensile tests were conducted to accurately determine material parameters, and the initial deformation of the specimen was precisely measured before the test. During the axial compression test, the deformation processes and load - time histories were systematically recorded. For the numerical simulation, a highly refined finite element model was developed in Abaqus/Explicit. The experimentally measured initial deformation was incorporated into the model to ensure accuracy. The Tsai-Wu, Shokrieh-Hashin, and modified LaRC03 failure criteria, combined with instantaneous stiffness degradation models, were implemented through VUMAT subroutines. Displacement-controlled loading was applied to simulate the axial compression process observed in the experiments.

Results The results demonstrate strong agreement between numerical simulations and experimental data. Compared to the experimental values, the Shokrieh-Hashin and LaRC03 criteria, when combined with instantaneous stiffness degradation, predict the ultimate strengths with errors of 5.7% and 2.7% respectively, while corresponding displacement errors are 3.8% and 2.1%, all within an acceptable range. The LaRC03 criterion, which accounts for fiber-matrix interaction failures, predicts a larger damage area in the face sheet, a slightly lower ultimate load, but greater deformation. In contrast, the Tsai-Wu criterion predicts premature failure, with an ultimate load error of 3.3% and a significant displacement error of 27.1%. The load-bearing behavior in the elastic phase of the simulation aligns well with experimental observations; but there are still certain differences, with the simulated ultimate load exceeding the experimental value. Additionally, the composite sandwich panels with steel stiffeners achieve a remarkable 40% weight reduction compared to the conventional steel-stiffened panels.

Conclusions The Shokrieh-Hashin criterion, in conjunction with the instantaneous stiffness degradation method, effectively predict the ultimate strength of composite sandwich panels with steel stiffeners, demonstrating high accuracy for fiber-dominated failure modes. The LaRC03 criterion, incorporating additional considerations such as fiber-direction matrix failure, provides more precise predictions, although its applicability is primarily limited to compressive loading conditions. The proposed composite sandwich panel with steel stiffeners not only realizes efficient lightweight design but also effectively lowers the center of gravity of the ship's weight. The experimental and numerical analysis on this structure establish a valuable and effective methodology for the lightweight design and strength analysis of ship superstructures. Future research should focus on optimizing material parameters and geometric configurations of the composite sandwich panel with steel stiffeners to further enhance structural performance and reliability. Additionally, considering the effects of marine environmental factors on structural integrity will improve its practical applicability in ship superstructures.