Al/PTFE reactive material have emerged as promising candidates for warhead casings due to their dual capability of structural integrity and chemical energy release. The energy release characteristics of Al/PTFE casing under explosive loading were investigated through confined explosion experiments integrated with high-speed data acquisition and 3D deformation scanning. Comparative analysis between bare charges and cased charges revealed distinct pressure profiles in confined spaces, complemented by numerical simulations elucidating target plate deformation dynamics. Experimental results demonstrated that reactive casings enhanced quasi-static pressure and temperature in confined explosions, with recorded increases of 57% and 52% respectively, with target plate residual deformation peaking at 46% under enhanced loading. Numerical modeling uncovered a non-monotonic trend: structural responses were overestimated in small-charge scenarios but underestimated in large-charge conditions. This characteristic indicated that the afterburning behavior of Al/PTFE reactive materials affected structural responses not through simple energy superposition, but via synergistic interactions between time-delay energy release mechanisms and evolving explosion environmental parameters. Further analysis indicated a 5.8% reduction in casing combustion efficiency due to energy competition between detonation products and reactive fragments. Notably, RDX-driven casings exhibited triple the combustion efficiency of TNT-driven counterparts, with fragment-induced deflagration accounting for approximately 70% of total energy release from casing combustion. These findings provide critical insights into reactive material explosions in confined spaces, offering theoretical foundations and optimization strategies for advanced warhead design and naval compartment blast protection.

This study investigates the vibration characteristics of butt-welded plate structures influenced by weldinginduced residual stress and deformation. A theoretical model incorporating the corrected elastic modulus is developed, along with a numerical model accounting for welding parameters. Both models were validated against experimental data. An empirical expression combined with sensitivity analysis is then proposed to analyze the influence of various welding parameters, with its reliability confirmed through experimental and theoretical comparisons. The experimental results indicate that the vibration characteristics of the plate structure are influenced by welding residual stress and deformation, with a 13.7 % decrease in the first-order natural frequency. The developed theoretical and numerical models achieve high prediction accuracy, with errors of 2.2 % and 2.6 %, respectively. Compared with the undeveloped model, the corrected model improved prediction accuracy by 11.5 % and 11.1 %. Sensitivity analysis reveals that welding speed is the dominant factor, while welding current becomes more significant when interaction effects are considered. Overall, this work provides a thorough framework for understanding and controlling the vibration properties of welded structures.

Acoustic coatings featuring low-frequency broadband sound absorption, high hydrostatic pressure resistance, and lightweight characteristics are crucial for acoustic stealth technologies in deep-sea equipment. However, traditional cavity-based acoustic coatings are limited by incomplete mechanism characterization and inefficient design workflows, failing to balance low-frequency broadband absorption and high load-bearing capacity. This study establishes a physics-guided hybrid modeling and inverse design method. First, theoretical analysis, numerical simulations, and machine learning methods are integrated to deconstruct the sound absorption mechanisms of cavity-based coatings. The competitive and synergistic effects among Fabry-Pérot (FP) resonance, cavity vibration, and local resonance are elucidated, and the triggering conditions for local resonance are quantified. Building upon this, a physics-guided acoustic-mechanical hybrid prediction model based on the "physical baseline + data-driven correction" strategy is constructed, which significantly improves prediction accuracy and computational efficiency while ensuring physical interpretability. Furthermore, a physics-guided multi-objective inverse design method is proposed. By directly incorporating the impedance matching criterion, local resonance mechanism, and thin-plate bending theory into the optimization algorithm, the traditional blind trial-and-error approach is transformed into a directional search. The results demonstrate that the optimized acoustic coating achieves highly efficient sound absorption in the deep sub-wavelength regime: without hydrostatic pressure, it realizes effective absorption ( ) down to 180 Hz with an average coefficient of 0.93 over 0–10 kHz; under 3 MPa hydrostatic pressure with maximum deformation constrained below 2 mm, it achieves effective sound absorption down to 440 Hz with an average coefficient of 0.92. Compared to the traditional Genetic Algorithm (GA), the optimization convergence efficiency of the proposed method is improved by two orders of magnitude. The method proposed in this study breaks through the constraints of traditional design concepts, providing a novel design method for cavity-based acoustic coatings that seamlessly combines physical transparency with engineering efficiency.

Shot peening significantly enhances the fatigue resistance of engineering components by introducing compressive residual stress (CRS) fields into the material surface layers. However, the relaxation of residual stresses under cyclic loading critically undermines the accuracy of fatigue life predictions. Existing predictive models predominantly rely on empirical formulas and extensive experimental data fitting, which neither elucidate the mechanical essence of stress relaxation nor provide practical engineering applicability. In this study, a residual stress relaxation prediction method is proposed based on the Equivalent Yield Strength Gradient (EYSG). To this end, systematic experiments were conducted, including shot peening treatment, microhardness testing, residual stress measurements, cyclic loading tests, and residual stress relaxation assessments. The stabilized residual stress field formed after mechanical loading was used as the benchmark, and the loading spectrum characteristics were incorporated into a mechanics-driven framework to inversely solve for the EYSG, thereby enabling the prediction of residual stress field distributions under high-cycle fatigue (HCF) conditions. Results demonstrate that the EYSG effectively characterizes gradient mechanical responses. The developed method achieves a prediction accuracy of 91.7% for the tested material under cyclic loading, and 90.0% accuracy for a reference material reported in the literature. Experimental validation confirms the method's capability for engineering-level residual stress relaxation prediction.

We propose a high-efficiency broadband underwater acoustic metamaterial (HEB-UAM) with a unique gratinglike structure made of wider rigid supports and damping layers. The design incorporates an internally embedded quasi-Helmholtz resonator configuration within the rigid support structure. We developed a theoretical model for the HEB-UAM absorption coefficient by combining slit absorption theory with the complex viscosity model and using the transfer matrix method (TMM). The theoretical predictions exhibit excellent agreement with the finite element method (FEM) simulation results. The insertion of rigid supports significantly enhances the shear deformation within the damping layers, thereby substantially improving the viscous shear dissipation of acoustic energy. The wider support helps offset the poor broadband absorption of low-impedance materials. The rigid support contains a quasi-Helmholtz resonator with a narrow slit, a water cavity, a damping layer, and an air cavity arranged in sequence. This carefully optimised configuration maximises the degrees of freedom for the cavity damping layer, resulting in significantly enhanced low-frequency acoustic energy absorption. Parametric studies elucidated the absorption characteristics of each component. Through particle swarm optimization (PSO) of unit cell parameters, the optimized structure achieves efficient sound absorption(alpha > 0.8) in the deep subwavelength regime(lambda/326 at 92 Hz). Notably, it maintains a high average absorption coefficient of 0.94 within the 0-10000 Hz frequency range. Furthermore, we discuss feasible approaches for lightweight design, loss factor reduction, and reduction in structural thickness. These findings highlight the strong potential of HEB-UAM for practical underwater sound absorption applications.

The present study aims to establish a framework for developing a practical design diagram based on an advanced ultimate limit state (ULS) analysis methodology for stiffened plates subjected to combined loads, namely compression, shear, and lateral pressure. The proposed approach consists of two parts: the design diagram and the explicit formulation. The necessary datasets for stiffened plate scenarios were generated through comprehensive numerical parametric analyses, providing valuable insights for enhancing existing safety assessment frameworks in ocean mobility. In total, 144 sets of design diagrams were derived, representing the relationships between ultimate shear and compressive strengths under various combined loading levels for conservative design applications. Furthermore, concise design formulas for predicting the ULS of stiffened plates under combined loads were proposed using symbolic regression (SR) algorithms. Unlike black-box intelligent models or conventional curve-fitting techniques, symbolic regression provides explicit equations that achieve a balanced trade-off between accuracy, interpretability, and complexity, thereby facilitating practical engineering applications. As the combined loading conditions considered herein more closely reflect the actual loading environments of stiffened plates in ships and offshore structures, the present work serves as a meaningful extension and complement to existing ULS assessment methodologies.

ObjectiveTo reduce the damage range of traditional spliced composite armor, a novel composite armor structure composed of titanium alloy faceplate, silicon carbide （SiC） ceramic, ultra-high-molecular-weight polyethylene（UHMWPE） laminate, and integrated titanium alloy lattice and back plate is proposed. And we employ optimal design of the structure to achieve the enhancement of the ballistic resistance and weight reduction. MethodComparative studies on the ballistic resistance of the novel composite armor is conducted by numerical methods. A high-accuracy surrogate model is established to rapidly predict the ballistic performance of the composite armor, and correlation analysis is performed between structural parameters and residual velocity and areal density. The structural parameters of the composite armor are optimized based on the NSGA-II multi-objective genetic optimization algorithm. ResultsThe results indicate that, compared with traditional spliced composite armor, the new composite armor reduces the residual velocity of the projectile by 11.7% and the damage range by 60.9% due to the presence of the integrated titanium alloy lattice and back plate. The damage range is confined to the inside of the grill, while the rest of the structure maintains better integrity. The anti-penetration performance of the areas with weak protection located at the splices is improved. After optimization, the residual velocity of the projectile is reduced by 21.0%, while the areal density decreases by 5.3%. The residual velocity of the projectile shows the strongest correlation with the thickness of the UHMWPE laminate and the weakest correlation with the thickness of the titanium alloy back plate. The optimized structural design scheme is as follows: the thickness of SiC ceramic is 4.25 mm, the thickness of UHMWPE laminate thickness is 10.65 mm, and the thickness of titanium alloy backplate thickness is 0.52 mm. After optimization, the residual velocity of the projectile is reduced by 21.0%, while the areal density reduced by 5.3%. Conclusion Compared with the traditional spliced composite armor, the novel composite armor structure demonstrates superior anti-penetration performance. The method for structural optimization design of composite armor based on the SVR surrogate model and NSGA-II algorithm is effective and feasible.

Full-scale testing remains most effective to investigate deck dynamic buckling, yet scaled-model testing is widely adopted by researchers due to economic and spatial constraints. The key challenge is developing reliable scaled design to predict Full-scale prototypes’ dynamic responses. In the current study, a universal similarity method for different structural forms, impact loading types and material constitutive equations was proposed according to the finite similitude theory. By scaling physical systems through mapping of Full-scale and scaled-down spaces, the scopes of application of the proposed similarity method were expanded to various structure forms, loading types and material constitutive relations, and thus facilitating the similarity design and prediction of structural responses under dynamic load. To verify the proposed method, systematic numerical validation analyses were conducted, including all the cases of stiffened plates under impact mass loads, the cases of stiffened plates under simplified sinusoidal triangular loads, and the cases of box girder models under simplified sinusoidal triangular loads. The validation results indicated that the proposed similarity approach had acceptable effects in keeping the same dynamic structural responses between prototype and scaled-down models. This study could be regarded as the supplement to the existing similarity research of dynamic responses of ship and ship-like structures.

This study investigates local scour around offshore wind turbine monopile foundations through an integrated framework combining three-dimensional numerical modelling, systematic parametric analysis, and quantitative scour risk assessment. A three-dimensional numerical model incorporating a dual-scale validation strategy based on benchmark flume experiments and prototype-scale multibeam bathymetric measurements is developed to improve the reliability of engineering-scale scour prediction. A systematic parametric analysis is then conducted to quantify the combined effects of sedimentary, structural, and hydrodynamic factors on scour depth, scour extent, and scour-hole morphology. Based on the numerical modelling and parametric analysis results, a quantitative scour risk assessment framework is established by integrating the Analytic Hierarchy Process with the weighted comprehensive index method. The numerical model shows good agreement with laboratory and field observations in terms of flow characteristics, scour-hole morphology, and maximum scour depth. The results indicate that current velocity and monopile diameter are the dominant factors governing scour intensity, whereas increasing sediment grain size effectively reduces both scour depth and scour extent. Water depth has a relatively limited influence on maximum scour depth but continues to affect the spatial development of the scour hole. Local scour is mainly concentrated within approximately three monopile diameters around the foundation, with the maximum scour occurring on the lateral sides owing to vortex-induced flow acceleration and sediment entrainment. The proposed framework establishes a quantitative link between numerical scour prediction and risk assessment, providing a practical basis for scour risk classification and protection strategy selection for offshore wind turbine monopile foundations.

Cased charges are usually simplified as equivalent bare charges to characterize the energy dissipation and conversion caused by fragmentation and initial kinetic energy of metal casing under the driven force from inner detonation pressure. However, this conventional simplification method inherently neglects the afterburning effects of detonation products, introducing significant risks when applying cased charge analytical models to confined explosions. In this paper, three different configurations of cased charge were employed to investigate the energy release characteristic in confined explosion scenarios experimentally and numerically. In addition, comparative analyses were performed between bare charges and cased charges. The test results reveal that the initial peak overpressure of cased charge was significantly lower than that of the bare charge, but the quasi-static pressures were very close to each other, maintaining differences within 6 %. Numerical simulations employing the Smooth Particle Hydrodynamics (SPH) method were conducted to quantify the energy dissipation caused by casing fragmentation. Based on detonation energy conservation principles, equivalent bare charges with mass reductions of approximately 30 % compared to the initial cased charges were derived. However, pressure load analysis demonstrates substantial discrepancies exceeding 50 % in quasi-static pressure predictions between equivalent bare charges and cased charge configurations. To address this limitation, a reactive flow-based model was developed, explicitly incorporating chemical reactions and casing-product interactions. The proposed model achieved excellent agreement with experimental pressure histories in both temporal evolution and magnitude. Furthermore, a two-phase pressure load simplification framework was established based on pressure distribution and evolution patterns, which successfully reconciled with dynamic responses of target plate recorded in experiments. Furthermore, the critical role of quasi-static pressure in governing structural dynamic responses within confined spaces was identified through numerical analysis.

As ship systems become increasingly integrated and complex, traditional ship design and development faces challenges in multidisciplinary collaboration and design verification. This study applies a Model-Based Systems Engineering (MBSE) approach using the HOPE methodology to model a ship cooling water system from requirements analysis to simulation validation, focusing on parameter sensitivity analysis and operating-range verification.Comparative simulations based on a parameterized constraint model capture how key parameters influence cooling performance. Within the tested range, a larger cylinder liner heat transfer coefficient lowers the steady-state liner temperature through a smaller heat-exchange temperature difference, while a higher seawater temperature mainly shifts the operating point upward. Within a feasible range of the heat transfer coefficient, the thermostatic valve compensates for both and keeps the liner within its target band, whereas too small a coefficient saturates the valve and the liner exceeds the limit-a boundary the simulation identifies before any hardware is built. These results show that design parameters can be pre-validated digitally rather than corrected after physical testing.More broadly, the model-based approach can reduce reliance on physical prototyping and limit interdisciplinary ambiguities in complex ship engineering, and a V-model framework can further support early-stage risk management and forward design.

This study proposed a geometrical distortion solution for the similarity design of box-girder under longitudinal compression load. The corrected distortional method by considering the plate thickness distortion effect was proposed to mitigate the similarity error caused by distortion effect during the similarity design process. The distortional method was based on the numerically obtained empirical formula for the stiffened plate component in the box-girder structure. A similarity procedure by combing the corrected geometrical distortional method and the previous material transformation method was finally put forward. The application of the similarity procedure was expected to reduce the distortion effect and improve the experiment test precision. The effectiveness of the proposed corrected distortional method and similarity procedure were well validated by both the experimental and numerical analyses in the current study.

In the design of small-scale test models for hull structures, the directional dimensional analysis method is commonly employed. However, conventional dimensional analysis based on elasticity theory may be insufficient to capture the nonlinear behaviors of structural materials under dynamic loading, which restricts its applicability in ultimate strength tests for small-scale hull structure models. This paper presents a scaling method grounded in the theory of finite similitude. Based on the finite similitude theory, this paper deduces similarity scaling criteria applicable to the static and dynamic responses of box girders and designs a series of trial models of box girders. The scaling criteria are verified and analyzed through numerical tests conducted under static and dynamic loads. On the basis of the numerical test results of dynamic responses, the dynamic response similarity criteria considering the similarity relationship of material constitutive parameters are modified and verified. By applying the static response scaling criteria in this paper to select appropriate materials, the prediction deviation of the box girder trial models under static loads is less than 2%. With the modified dynamic response scaling criteria proposed in this paper, the prediction deviations of each trial model under dynamic loads are less than 2% and 7%. A comprehensive analysis of material parameters was conducted to examine their impact on the nonlinear similarities observed in the processes. To validate the ultimate strength and nonlinear response scaling criterion based on the finite similitude approach, numerical experiments were performed to assess the ultimate strength and dynamic buckling response characteristics of the box girder across various scaling ratios and material parameters. The analysis demonstrated that the ultimate strength scaling criterion and the nonlinear response scaling criterion derived from the finite similitude approach effectively captured material nonlinearity. The results from the small-scale model provided accurate predictions of the ultimate strength of the full-scale model.

This study experimentally and numerically investigated the ultimate behaviours of the large-span double-layer structures with large openings on modern passenger ships under different types of loading conditions. The ultimate strength experimental research of the objective structure under combined bending and lateral pressure conditions was first conduced. A comprehensive parametric study containing 216 scenarios were then carried out based on the experimentally validated finite element method. Besides the sagging conditions, both the hogging and torsion conditions were further considered in the numerical parametric analyses. The parametric results indicated that the openings on upper decks exhibited a significant deteriorating effect on the ultimate strengths of the objective structure, while the influences of the lateral pressure could vary between deterioration and enhancement effects depending on the types of loading conditions. A simplified polynomial-shaped empirical formula was finally proposed based on these parametric results, which could be utilized to predict the ultimate strengths (sigma byu and sigma txu) of the objective structures under both the hogging bending and torsion conditions by considering the influences of large openings (LO/LC and BO/B) and lateral pressures (qE/sigma 2Y). The developed empirical formula could be useful for the lightweight design and safety assessment of structures on modern large passenger ships.

The effects of three inulins (IN) with different polymerization degrees on the structure, properties and digestibility of rice starch (RS) were investigated. The results showed that the viscosity, breakdown, and setback values of the composite systems decreased. Compared to pure starch, the gelatinization enthalpy of composite systems significantly decreased from 9.54 J/g to 9.13 J/g, 9.05 J/g, and 8.79 J/g, while the retrogradation enthalpy after 14 d storage declined from 4.58 J/g to 3.44 J/g, 3.72 J/g, and 3.85 J/g. The addition of IN significantly reduced the relative crystallinity and formation of ordered structures in the composite systems after 14 d of storage. Digestibility analysis revealed a significant decrease in rapidly digestible starch (from 69.63 % to 45.48 %, 48.38 %, and 50.00 %) and increases in slowly digestible and resistant starch contents. The effects depended on IN's polymerization degree and concentration, with 3.0 % short-chain IN demonstrating the most pronounced improvement in starch properties.

The synergistic effect of fermentation (Lactobacillus plantarum) and heat-moisture treatment (HMT) on the quality of rice flour and rice noodles was emphatically studied, and the correlation between the quality of rice flour and rice noodles joint or separate treatment was comprehensively compared and analyzed. Fermentation combined with HMT increased the pasting temperature and the retrogradation value of rice flour, which also improved the digestive starch. The combination of fermentation and HMT made rice flour show the characteristics of solid gel and improved its elasticity and increased sensory scores and the content of resistant starch in rice noodles and reduced cooking loss. Through correlation analysis, it was found that the pasting properties (peak viscosity and trough viscosity) of rice flour were most closely related to the cooking loss, texture profile, and sensory evaluation of rice noodles. The results provide an effective approach for starch modification and improving the quality of rice noodles.

Composite armor plays a crucial role as the primary defense against high-velocity impacts from fragments and projectiles. However, balancing the need for lightweight structures with the requirement for robust protection remains a significant engineering challenge. Traditional approaches for predicting the protective performance of armor typically involve a combination of experimental testing and numerical simulations, both of which can be resource-intensive and costly. In contrast, data-driven methods combined with machine learning have demonstrated the potential to significantly reduce both time and economic costs, highlighting their substantial advantages in various engineering domains. Unfortunately, a mature machine learning framework for predicting the performance of multilayer composite armor against high-velocity impacts from large fragments has yet to be established. In this paper, a novel data-driven framework for predicting the ballistic performance of composite armor using a hybrid model of Support Vector Machine and Deep Neural Network was established. This framework employed hyperparameter optimization to enhance predictive performance, yielding a model with excellent accuracy. The proposed model was adaptable to multilayered armor with varying layer thicknesses, enabling rapid predictions of armor penetration, residual projectile kinetic energy, and armor deformation.

The digital twin refers to a virtual representation of a physical object, system, or process using digital techniques like sensors and simulation models. The successful structural digital twin of ship structures is expected to provide designers with high-frequency feedback and reliable predictive results, thereby enhancing safety assessments of the structures. However, there are still many gaps in existing techniques in achieving these expectations. One prominent problem is that existing boundary methods in numerical analyses cannot accurately describe the boundary constraint effects on the objective structures. This would inevitably cause significant errors in the predictions from finite element analysis-based surrogate models. This study aims to improve existing finite element analysis-based surrogate model strategies by proposing a precise method for describing boundary constraints based on elastic boundaries. A boundary-driven model-updating approach was subsequently proposed together with an enhanced framework for establishing integrated surrogate models. Finally, an experimental case study was conducted to validate the proposed approach. This study can be regarded as an essential foundation and complement to future structural digital twins of ship structures.

The elevated superstructures of cruise ships are susceptible to wind load effects, which subsequently generate aerodynamic noise on open decks, adversely affecting passenger comfort. This study established an acoustic radiation method suitable for large-scale complex acoustic environments on open decks-the Directional Compact Acoustic Source method-through acoustic wind tunnel tests and numerical simulations. The methodology characterizes aerodynamic noise source properties through directional acoustic source modeling and achieves large-space directional sound radiation via the ray tracing method. The validity of this approach was verified through comparison with experimental results and traditional methods. Furthermore, the radiation characteristics of aerodynamic noise from the top windshields to the open deck were investigated by integrating the subdomain method. Results indicate that sound pressure levels (SPL) peak at the lateral edges of the open deck and reach minimum values in central areas, with the highest SPL occurring at lying positions. Sound source contributions at the edge significantly exceed those at the center, particularly impacting seated passenger positions. This research provides valuable insights for enhancing acoustic comfort design on cruise ship open decks.