Locally resonant phononic crystals are a kind of artificial periodic composite material/structure with an elastic wave band gap that show attractive application potential in low-frequency vibration control. For low-frequency vibration control problems of ship power systems, this paper proposes a phononic crystal board structure, and based on the Bloch theorem of periodic structure, it uses a finite element method to calculate the band structure and the displacement fields corresponding to the characteristic mode and vibration transmission curve of the corresponding finite periodic sandwich plate structure, and the band gap characteristics are studied. The mechanism of band gap formation is mainly attributed to the mode coupling of the phononic crystal plate structure. Numerical results show that the sandwich plate structure has a double periodicity, so it has a multi-stage elastic wave band gap, which can fully inhibit the transmission of flexural waves and isolate the low-frequency flexural vibration. The experimental measurements of flexural vibration transmission spectra were conducted to validate the accuracy and reliability of the numerical calculation method. On this basis, the potential application of the proposed vibration isolation method in a marine power system is discussed. A vibration isolation platform mounted on a steel plate is studied by numerical simulation, which can isolate low-frequency vibration to protect electronic equipment and precision instruments.

High-pressure gaseous hydrogen storage is widely adopted in the hydrogen energy industry chain due to its simplicity, reliability, and economic viability. However, when these systems are subjected to rapid filling, a series of complex thermodynamic behaviors are induced. These have been identified as a bottleneck restricting the safety and service life of hydrogen storage and transportation equipment. In this paper, a detailed review is conducted on the recent domestic and international research progress regarding the thermodynamic issues encountered during the charging process of storage devices. Research achievements related to the thermodynamics of the process are systematically classified, summarized and discussed. These achievements are analyzed from four aspects: thermodynamic theoretical models, numerical simulation analysis, experimental testing, and thermal management strategies. The thermodynamic mechanism of the charging process is revealed, and the variation laws of thermodynamic responses during charging are sorted out. Key factors affecting the thermodynamic behaviors of charging are clarified, and the implementation effects of different thermal management strategies are elaborated. Finally, based on the future development trend and prominent potential challenges in high-pressure hydrogen storage, the future development directions of the thermodynamics of hydrogen fueling in storage and transportation devices are explored and prospected.

This study conducts multi-scale numerical simulations spanning atomic to macroscopic scales (i.e., from nanometer to millimeter scale) to investigate the fatigue crack propagation behavior in the welded heat-affected zone (HAZ) of AH36 shipbuilding steel. A coupled molecular dynamics–finite element method (MD-FEM) was employed to establish a multi-scale model. Through the transfer of boundary displacements, equivalent mapping of crack morphology, and crack-tip tracking, an iterative multi-scale simulation of 600 tension–tension fatigue cycles was achieved. The results indicate that the crack propagation rate is significantly influenced by crack tip morphology (blunting/sharpening) and growth direction. Notably, the peak strain at the boundary is not the sole determining factor. Periodic blunting of the crack tip occurs during cyclic loading, accompanied by a decrease in the propagation rate. Additionally, the stress field near the crack tip induces microscopic defects such as voids in the nearby area, affecting the crack propagation. This study, based on multi-scale analysis, reveals the microscopic mechanism and evolution law of fatigue crack propagation in the heat-affected zone of AH36 steel welds.

Liquid hydrogen (LH₂) has been regarded as an ideal carrier for large-scale and long-distance hydrogen energy storage and transportation due to its high gravimetric hydrogen storage density, rapid refueling efficiency and favorable safety performance. However, the physical properties of LH₂, such as low viscosity and high volatility at the ultra-low temperature of −253 °C, cause complex thermodynamic problems during the refueling process—including drastic phase transitions, concentrated thermal stress, and two-phase flow instability—which act as bottlenecks restricting the large-scale application of LH₂. In this paper, research advances achieved domestically and internationally in recent years are reviewed in detail with respect to thermodynamic issues occurring in the ultra-low-temperature LH₂ refueling process. Research achievements concerning the thermodynamics of LH₂ refueling are classified, summarized and discussed from the perspectives of theoretical thermodynamic analysis, numerical simulation, experimental investigation and refueling process optimization strategies for LH₂ refueling. The heat and mass transfer mechanisms involved in LH₂ refueling are revealed, the variation in thermodynamic responses during the refueling process is described, the critical factors affecting the thermodynamic behaviors of LH₂ refueling are clarified, the industry standards on LH₂ refueling are critically assessed, and various refueling process management strategies are discussed. Finally, the future development directions of thermodynamic research on the LH₂ refueling process are discussed and prospected on the basis of the development trends and potential prominent challenges faced by LH₂ refueling technologies.

This paper proposes a ceramic ball/nylon elastomer composite structure. Experimental testing and finite element analysis were conducted to investigate the influence of key factors on the penetration resistance of the composite structures with constant total thickness. These factors include...

This study presents a multiscale numerical simulation of the behavior of crack growth in the heat-affected zone (HAZ) of AH36 marine steel welded joints under fatigue loading from the micro-scale to the macro-scale. The MD-FEM method and the multiscale coupling-optimized XFEM method were used to simulate fatigue crack propagation from micro-scale to meso-scale and from meso-scale to macro-scale. A total of 10,900,788 tension–tension fatigue cycles was realized. Information across different scales was transferred via boundary displacement transfer, crack morphology equivalence, and tip tracking. Building upon our previous investigation into fatigue crack growth behavior at the micro-scale, in which crack extension was limited to 469 Å, the present study encompasses the complete process of fatigue cracking from micro-scale initiation to macro-scale instability. Furthermore, the crack tip morphology and propagation pathways obtained from micro-scale molecular dynamics simulations are employed to optimize and calibrate the corresponding XFEM simulations at both the meso- and macro-scales. Results demonstrate that the phenomenon of interconnection between voids and the main crack near the crack tip has a significant influence on the crack propagation rate and path. During cycling, the propagation rate of the main crack increases significantly during its interconnection with voids, whereas crack propagation is significantly hindered when the interconnection is completed or when voids undergo self-closure. Furthermore, both theoretical simulations and experiments revealed the occurrence of crack propagation instability at the meso-scale. The present examination of the entire fatigue crack propagation process indicates that the MD-FEM method and the multiscale coupling optimized XFEM method in this study are fundamentally accurate in representing both the crack propagation process and the crack tip morphology. The results obtained in this paper can serve as a reasonable prediction of fatigue damage mechanisms in the HAZ of AH36 marine steel welded joints.