This paper aims to design a practical adhesive connection structure between the composite deckhouse and the steel main hull, and to evaluate the load-bearing property and failure behavior of local joints under the overall structural loads acting on the deckhouse.

Using the submodeling approach, the local joint region is coupled with the whole deckhouse model, and a parametric analysis is conducted on the adhesive layer through numerical simulations focused on the composite-to-steel slot connection scheme. Subsequently, the mechanical response characteristics of the connection area at the base of the deckhouse under splash loading conditions are evaluated, and a localized destructive test is conducted to investigate the failure modes of a real-size connection specimen.

The calculation results show that under splash-induced loading, the stresses in all parts of the adhesive connection structure remain below the ultimate material strength, maintaining a reasonable safety margin. When the load reaches approximately 3-fold the standard design load, initial damage mainly occurs at the corner of the stiffening beam skin. At around 10-fold the standard design load, the stiffening beam skin fails almost completely. Moreover, the damage features observed in the actual loading tests accord well with the results obtained from the refined local joint model.

This proposed slot adhesive connection structure is reliable and effective in meeting the strength requirements for the connection between the composite deckhouse and the steel main hull, and provides a useful reference for the engineering application of composite superstructures in the shipbuilding industry.

This study aims to investigate how quasi-3D spiral acoustic black holes (Q-3D SABHs) reduce vibrations in flat plate structures. It seeks to provide a new technical approach for designing ship plate structures with improved vibration damping. With the increasingly stringent requirements for noise and vibration control in marine engineering, this study addresses the need for efficient and broadband vibration reduction methods.

To achieve this objective, a new configuration of the Q-3D SABH is proposed to achieve effective broadband vibration reduction. A detailed finite element computational model of a flat plate with attached Q-3D SABH structures is developed. The vibration response characteristics of the plate are systematically analyzed through numerical simulations. Furthermore, the structural intensity distribution and modal loss factors are calculated to investigate the underlying damping mechanisms and the effectiveness of energy convergence and dissipation induced by the Q-3D SABH. Comparative analyses are also conducted to evaluate the performance of the Q-3D SABH against conventional vibration damping methods, such as mass blocks, traditional damping materials, and one-dimensional spiral acoustic black holes (1D SABH) with equal mass.

The results demonstrate that the Q-3D SABH exhibits significantly better vibration damping performance than conventional treatments, such as adding mass blocks or using traditional damping layers, and also outperforms 1D SABH of the same mass. Specifically, in the low-frequency band, the Q-3D SABH configuration effectively reduces the mean-square vibration velocity level of the flat plate by more than 10 dB. In the mid- and high-frequency bands, the vibration damping performance is even more significant, achieving reductions of over 15 dB. Across the entire frequency range analyzed, the total vibration level is reduced by 15.05 dB. Moreover, compared to 1D SABH structures of equivalent mass, the Q-3D SABH demonstrates superior damping performance, particularly in the mid- and high-frequency ranges.

The study concludes that the Q-3D SABH structure has an excellent ability to converge and dissipate bending wave energy. The Q-3D SABH structure achieves outstanding broadband vibration reduction, especially at low frequencies, which are often challenging for traditional damping methods. These findings provide theoretical and technical support for the innovative design of vibration and noise control solutions in ship plate structures and other engineering applications where lightweight and efficient damping is critical. This research highlights the promising application potential of Q-3D SABH in advancing vibration damping technologies for large flexible structures.

To improve the cooperative detection efficiency and mission stability of AUVs in complex underwater environments, this study proposes an improved MADDPG algorithm combined with the artificial potential field (APF) method.

To overcome the limitations of conventional APF in path planning, such as local optima, and the drawbacks of MADDPG, such as poor convergence and training instability due to random early-stage exploration, this study proposes the APF−MADDPG algorithm, which integrates APF's attractive field to guide AUVs' initial movement. The key innovations include: 1) constructing a dynamic, time-varying potential field model that adjusts the field strength coefficient in real time to enhance early-stage exploration; 2) employing Monte−Carlo simulations to generate possible target trajectories, statistically analyzing their spatiotemporal distribution in the operational area, and establishing a probabilistic model to predict the dynamic movements of underwater targets; and 3) integrating sonar detection probabilities at varying distances into the reward function design and path evaluation metrics with the use of the cumulative detection probability (CDP) formula. Comparative simulations were conducted for cooperative detection tasks involving 2 and 3 AUVs under identical initial conditions to evaluate the performance differences between the APF−MADDPG and conventional MADDPG algorithms.

The experimental results demonstrate that: In terms of detection performance, APF−MADDPG achieves a CDP of 80.93% in the 2-AUV scenario, representing a 7% improvement over conventional MADDPG, while in the 3-AUV scenario, it reaches 92.67%, showing a 0.6% increase;

Regarding algorithmic performance, APF−MADDPG exhibits superior initial convergence speed and final convergence stability in both scenarios; In stability tests, the improved algorithm shows less performance fluctuations across repeated trials, confirming its superior robustness.

This paper seeks to investigate the vibration reduction characteristics of a spiral acoustic black hole (SABH) on a ring-stiffened cylindrical shell and provide a new technical approach for the vibration reduction design of ring-stiffened cylindrical shells.

First, a finite element computational model of a ring-stiffened cylindrical shell with an SABH arrangement is constructed, and its structural natural frequency and vibration response characteristics are calculated and analyzed. The influence of the SABH arrangement position, helix length, and number on the vibration suppression of the ring-stiffened cylindrical shell is also investigated.

The results show that with a single SABH arranged on the web, the resonance peak of each mean-square velocity （MQV） of the web is significantly reduced, with the first-order resonance peak reduced by 6 dB or more, the other resonance peaks reduced by 13 dB or more, and the peak value of each MQV of the shell reduced by 8 dB or more. Increasing the helix length and number of SABHs can further improve the vibration reduction effect.

SABHs have a minimal effect on the natural frequency of ring-stiffened cylindrical shells and deliver excellent low-frequency broadband vibration reduction performance.

This study analyzes the influencing factors of the aeroacoustic noise of cruise ship chimney exhaust pipelines, and predicts the noise level in the open area of a domestic cruise ship.

A hybrid approach combining Large Eddy Simulation and Lighthill Analogy is used to conduct a numerical simulation of the pipeline’s aeroacoustic noise under the actual working conditions of a cruise ship. The impacts of the inlet flow rate, outlet pressure, cross-section shape and bending angle on the aerodynamic noise are studied. A real-size cruise ship chimney exhaust pipeline model is then established to analyze the main noise sources and predict the noise level in the open areaa.

The results show that the larger the inlet velocity and bending angle, the greater the aeroacoustic noise. Furthermore, the aeroacoustic noise of a pipeline with a zero pressure-outlet is greater than that with a non-zero pressure-outlet. It is also found that the aeroacoustic noise of a rectangular cross-sectional pipeline is marginally smaller than that of a circular one. In addition, the narrowband peak frequency decreases as the bending angle increases. Except for the chimney outlet, the noise level in the open area is low.

This study has significant reference value for controlling the aeroacoustic noise of cruise ship chimney exhaust pipelines and improving passenger comfort in open areas.

The open area of the superstructure of a luxury cruise ship has a complex spatial layout and appearance modeling. In this study, the wind load and flow field characteristics in this area are accurately simulated to guide cruise ship design.

The realizable k−ε turbulence model and substructure method in the Reynolds time-average method are used to numerically simulate the flow field characteristics of the whole cruise ship and the open area of the superstructure, and wind tunnel experiments are carried out for verification.

The appearance and spatial layout of the open area of the superstructure have an important impact on the flow field characteristics of the cruise ship, and the substructure simulation method can accurately simulate the flow field characteristics of the local area.

When designing cruise ships, the overall shape of the superstructure should be streamlined and the height difference and spacing between adjacent structures in the open area should not be too large. The results of this study can provide guiding references for cruise ship design.

This paper aims to study the wind-induced noise of typical rods in the open areas of cruise ships.

The numerical simulation of aerodynamic noise and wind-induced vibration noise is carried out using computational fluid dynamics (CFD) combined with the acoustic analogy method and vibro-acoustic coupling method in order to explore the generation mechanisms and characteristics of the two kinds of noise.

Under different wind speeds, the maximum frequency of aerodynamic noise is dominated by the vortex shedding frequency, while the maximum frequency of wind-induced vibration noise is dominated by the natural frequency of the structure. The aerodynamic noise of three different cross-section rods is generally greater than that of wind-induced vibration noise, and the aerodynamic noise of square rods is the greatest. Under large flexibility, when the fluctuating pressure frequency of the rod is close to the natural frequency, the wind-induced vibration noise will be close to or even exceed the aerodynamic noise.

In the design of typical rods to be applied in the open areas of cruise ships, in order to reduce wind-induced noise, circular rods should be selected, square rods should be avoided, reasonable rod sizes should be selected and the vortex shedding frequency of the rods should not be close to the natural frequency.

Welding is a common method for connecting ship structures, but it obviously affects their acoustic and vibration characteristics. Thus, it is necessary to study the influence of welding process parameters on the acoustic and vibration characteristics of structures.

In this paper, the thermo-elastoplastic finite element method and acoustic-structure coupling finite element method are combined to study the influence of welding parameters on the acoustic and vibration characteristics of typical ship stiffened plate structures.

The results show that welding residual stress is significantly affected by welding input power and speed. Higher welding input power and lower welding speeds both result in a larger welding residual stress distribution range which causes changes to the natural frequency, vibration response and radiated sound pressure of typical stiffened plate structures.

Welding residual stress should be analyzed to determine the acoustic and vibration response of low-damping welded structures, thereby providing guidance for the formulation of low-noise welding processes.