To enhance the bending mechanical properties of fiber-reinforced plastics (FRP) and address rapid damage repair under multiple bending loads, an improved shape memory alloy hybrid composite (ISMAHC) was developed by embedding layered orthogonal shape memory alloy (SMA) wires into FRP. Three-point bending and water bath recovery tests were performed on traditional single-layer unidirectional SMA hybrid composites (SMAHC), ISMAHC and FRP. The effects of layered orthogonal SMA configuration on stiffness, strength, and recovery capability were compared and investigated. Results demonstrate that SMA wires form a coupling effect with FRP, increasing the bending modulus. Furthermore, ISMAHC has higher stiffness due to its orthogonal architecture. The water bath recovery tests indicate that SMAHC and ISMAHC possess good deflection recoverability and mechanical property recoverability after multiple bending loadings. The deflection recovery rate of the first bending test is greater than 60%, and that of the second bending test is greater than 30%. Additionally, the bending modulus and bending strength recover more than 30%, with ISMAHC showing superior recoverability.

With in-depth research on honeycomb structures for ship protection, diverse 3D honeycomb configurations have emerged. This paper aims to explore the traits of different 3D honeycomb designs and offer ideas for the future structural layouts. Both experimental tests and numerical analysis on the mechanical properties of 3D plate-frame and truss honeycombs were carried out. The test samples, made of nylon via laser sintering in an additive manufacturing process, underwent quasi-static compression tests to uncover the disparities in deformation patterns between the two honeycombs. By closely examining typical cell deformations during compression, the differences in failure modes were revealed. Because the load-bearing capacity of a structure and its density, the authors while studying these two types of honeycombs, also explored the relationship between the specific stiffness and nominal density of various typical 2D and 3D structures. Finally, a parametric analysis was performed to assess the impact of internal concavity angles, cell thicknesses, and materials on mechanical properties.

The maritime environment and loading conditions encountered by large ore carriers are highly complex. It is a problem worth studying to scientifically describe the uncertain load of ore carriers and evaluate the safety margin of hull beams quantitatively. This paper investigated the stochastic characteristics of environmental loads and ship internal loads and explored methods for combining multiple loads and their nature mechanics. This research also revealed the still-water bending moment characteristics under typical loading conditions. WALCS hydrodynamic analysis software was used to calculate the wave load response function of the target ship. The extreme values of the wave bending moments were obtained using the extreme value type I (Gumbel type I) long-term forecasting method. The statistical characteristics of the wavebending moments were analyzed. Based on the uncertainty load combination method, the hull girder safety margin of the target ship was obtained as 1.10-1.20. The rationality of the load system specified in the CCS rules for ore carriers is further validated. The results show that the method can be applied to the formulation of relevant ore ship rules by CCS and effectively reveal the safety margins behind the rules. Understanding of the GBS-type ship rule has been enhanced. This research provides an important reference for the development of large ore carriers.

Corrosion-fatigue coupling presents significantly greater risks than damage mechanisms in isolation. This review synthesizes recent research advancements in theoretical frameworks, computational simulations, and experimental methodologies, with a focus on the pitting evolution and crack propagation stages. Existing models of pitting morphology are commonly constrained by single-defect assumptions and geometric regularization, which hinder a comprehensive and multidimensional characterization of pits. In the modeling of crack propagation, three primary paradigms have emerged: mechanism-driven models, data-driven models, and hybrid-enhanced models. Among these approaches, physics-informed neural networks demonstrate considerable potential in addressing complex interactions between corrosion and fatigue. A critical issue identified is the empirical oversimplification in pitting characterization, particularly the assumption of geometric regularity, which serves as a key bottleneck in quantifying corrosion-fatigue synergies. To overcome this limitation, there is a need to develop integrated multidimensional quantification methods that incorporate size, shape, irregularity, and statistical distribution. This area represents a pivotal research frontier. Advancements in this field will lead to transformative insights into the fundamental coupling mechanisms and the assessment of structural integrity for engineering systems. Ultimately, this will facilitate the development of highly accurate corrosion-fatigue life prediction models, which are essential for ensuring the safety of infrastructure.

Extreme ice floe impact events on polar ship structures are very common in ice regions. The inelastic deformation of structures under ice impact loadings reflects directly the damage states of the structures and is thus an important and convenient parameter in structural strength assessment and design. Therefore, the aim of this paper is to review the recent research progress on dynamic inelastic response of polar ship structure subjected to ice floe impact. Some important experimental, numerical and theoretical work was introduced to study dynamic plastic responses of ship plates under single and repeated ice impact loadings. The effects of ice deformation and damage characteristics on the plastic energy absorption of ship plates were evaluated in this paper by comparing with rigid mass impact responses. In addition, the plastic deformation accumulation, energy-sharing mechanisms and pseudo-shakedown phenomenon of ship plates subjected to identical repeated ice impacts were explored. Based on the analytical solutions for inelastic response of ship plates under ice impact, some plastic design formulae and curves were proposed to determine the thickness of ship plates under ice impact loading, which can provide useful references for the structural design of ice-going ships.

In ocean engineering and coastal protection, a precise understanding of the interaction mechanism between breaking waves and offshore structures is a fundamental scientific issue for ensuring operational safety and enhancing protection efficiency. Based on the open-source computational fluid dynamics platform OpenFOAM, this study innovatively combines the thincFoam solver using the THINC/QQ interface capturing scheme with a stable k-ω SST turbulence model to develop a high-fidelity numerical framework for the detailed simulation of wave breaking processes. The proposed model achieves high-resolution capture and quantitative analysis of key physical parameters during wave breaking, including the evolution of free-surface morphology, dynamic flow field structures, pressure peak characteristics, and energy dissipation mechanisms. Numerical verification demonstrates that the proposed model has excellent predictive ability for solitary wave propagation, accurately reproducing the free-surface elevation as well as the spatio-temporal distribution of the velocity and pressure fields. Through systematic numerical experiments, this study elucidates the multi-scale wave dissipation mechanisms of pile-type breakwaters under solitary wave action: Turbulent mixture induced by free-surface fragmentation, oscillatory jets generated in the gaps between piles, vortex structures formed in the wake region, and wave breaking caused by nonlinear interactions between backflow and the remaining wave body. These processes collectively constitute a multiphysics synergy mechanism for wave energy dissipation. The findings not only provide a theoretical foundation for the optimized design of pile-type breakwaters but also offer an effective numerical tool for simulating wave-structure interactions, contributing to the theoretical development and technological progress in the field of ocean engineering.

To improve the C-type turning performance of a biomimetic robotic shark, the kinematics and hydrodynamics of the C-type turning motion of a self-propelled robotic shark were studied using Computational Fluid Dynamics (CFD) simulation method. A simulation model of the robotic shark and its turning kinematic and dynamic equations were established. The influences of parameters such as the minimum curvature radius R₀ of fish body bending, the asymmetry coefficient R_s of caudal fin, and the distance between fish and wall (dh) on turning velocity and hydrodynamic parameters were numerically studied, and the evolution process of flow field structure during C-type turning process was analyzed. The results indicate that the smaller R₀ is, the shorter the turning distance becomes and the larger the turning angle is. The asymmetric caudal fin can contribute to improving turning performance, but excessive R_s will lead to a decrease in turning stability. The wall effect is conducive to increasing turning speed and reducing turning distance.

When the frequency of external wave excitation or that of platform motion approaches the natural frequency of the moonpool structure, intense resonance phenomena occur within the moonpool. Under such conditions, both the water inside the moonpool and the platform motion exhibit strong nonlinear characteristics. Based on computational fluid dynamics (CFD) principles, this study conducts numerical simulations of a deep-draft cylindrical platform under regular wave action to investigate the influence mechanisms of incident wave frequency and environmental wave height on the coupled system of platform motion and moonpool water dynamics. The results indicate that increasing environmental wave height intensifies nonlinear phenomena in the moonpool water motion, characterized by enhanced resonance peaks in high-frequency bands and reduced piston-mode resonance peaks. A strong coupling relationship exists between platform motion and moonpool water dynamics, where both the moonpool resonance phenomena and platform motion responses demonstrate dual-peak characteristics. As the environmental wave height increases, the heave response amplitude operator (RAO) amplitude decreases, while the platform’s pitch RAO amplitude increases.

Under low-speed and deflection conditions, water-lubricated journal bearings (WLJBs) with large length-to-diameter ratios frequently exhibit abnormal wear and frictional vibrations, significantly compromising ship reliability and stealth capabilities. However, comprehensive experimental investigations on full-scale WLJBs remain insufficient, and the evolutionary mechanisms of dynamic behaviors under varying service conditions require further exploration. This study developed a distributed testing system for WLJBs based on a full-scale propulsion shafting test rig, and conducted running-in, speed characteristic, and elevation characteristic tests. From the perspective of tribological characteristics and lubrication zoning, the dynamic behavioral variations of different lubrication sub-regions under operational conditions are systematically revealed. The experimental results demonstrate that increased rotational speeds exacerbate shaft journal deflection, inducing hydrodynamic pressure peak migration toward the free-end lubrication sub-region; elevation modifications alter load distribution patterns among lubrication sub-regions, and distinct lift-off characteristics emerge among different lubrication sub-regions. These results provide critical validation data for developing dynamic models and optimizing structural designs of full-scale WLJBs in marine propulsion systems.

The coexistence of waves and broken ice is a prominent feature in marginal ice zones. Ships navigating in these areas are subjected to combined loads from both ice and wave actions. While current research has obtained substantial findings on ship ice resistance characteristics under either single wave or ice conditions, studies on coupled wave-broken ice interactions remain relatively scarce, resulting in insufficient understanding of the ship-ice-wave interaction mechanisms and their impacts on vessel navigation performance. To investigate ice resistance characteristics in broken ice fields under wave effects, this study developed a numerical model by adopting a coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) for ship navigation in wave-affected broken ice environments. The numerical wave tank was first established using the Finite Volume Method (FVM), while the broken ice model was developed through the Discrete Element Method (DEM). The validity of the ship resistance model under either single wave or ice conditions was verified through comparisons between theoretical solutions and experimental data. Subsequently, the ice resistance characteristics of ships navigating in wave-affected broken ice fields were systematically analyzed, with particular focus on the influences of wave parameters and ice concentrations. The results demonstrated that wave action significantly alters the ship-ice interaction process, inducing distinct periodic fluctuations in ice resistance. Notably, the ice resistance under combined wave-ice conditions consistently exceeds that observed in still water conditions with equivalent ice concentrations. Furthermore, the influence of key parameters including wavelength, wave height, and ice concentration on ice resistance behavior was also elucidated.