Ceramic/metal composite materials were widely used in national defense, military industry, and aerospace fields as lightweight impact-resistant structures with high specific strength and high energy absorption efficiency. With the development of 3D printing technology, it has become possible to fabricate complex lattice structures based on triply periodic minimal surfaces (TPMS). In this paper, an interpenetrating TPMS ballistic composite structure composed of silicon carbide (SiC) ceramic and titanium alloy (TC4) is designed. A series of numerical simulations are carried out under single-projectile and double-projectile penetration conditions using ABAQUS software. The damage modes, penetration depth, and ballistic limit velocity of the proposed structure and pure SiC target plate are compared and analyzed. The simulation results show that different interpenetrating TPMS structures exhibit distinct damage and failure modes. The three-dimensional topological configuration restrains crack propagation inside the ceramic, resulting in slighter overall damage than the pure SiC target plate. The damage caused by the second projectile further propagates along the penetration region of the first projectile, and accompanied by an increase in penetration depth. Compared with the pure SiC target plate, the three interpenetrating TPMS targets present smaller penetration depth and higher ballistic limit velocity. When the projectile can perforate the target plate, the primitive (P-type) structure shows better ballistic performance against low-velocity projectiles, while the diamond (D-type) structure is superior against high-velocity projectiles. It is demonstrated that the interpenetrating TPMS targets possess better ballistic performance than pure SiC at the same area density. The technical support and theoretical basis can be provided for the design of novel lightweight ceramic armor in this study.

Metamaterials with both reversible deformation and a long load plateau meet the demand for cyclic buffering, offering great application prospects in protective engineering. However, current metamaterials generally suffer from low material utilization, which limits their load-bearing and energy absorption performance. To address these limitations, a novel buffering metamaterial with a long load plateau is proposed in this work. Composed of bilaterally symmetric double-arc structures and vertically symmetric curved plates, the metamaterial is capable of recoverable large deformation and overall cooperative load-bearing deformation, thereby improving material utilization and optimizing structural load capacity and energy absorption performance. Experimental tests and numerical simulations were conducted to validate the long load plateau and recoverable large deformation characteristics of the metamaterial. The influences of structural geometric parameters on its mechanical behavior were also systematically analyzed. The results indicate that the long load plateau can be effectively tuned by adjusting the thickness of lateral double arcs, the thickness of intermediate curved plates, and the central transverse span. Once the intermediate curved plates are removed, the long load plateau feature disappears, and the force-displacement curve presents an approximately linear variation. Finite element simulations at equal mass confirm that the proposed metamaterial possesses better buffering performance than similar structures without a long load plateau, and the underlying buffering mechanism is clarified. The findings provide a novel design strategy for improving the performance of metamaterials with a long load plateau, and facilitate their application in protective engineering.

A bio-inspired fractal multi-cell circular (BFMC) tube with embedded regular polygons is proposed to address the gap between the need for high absorption and the limited performance of traditional thin-walled circular tubes. Inspired by biological structures and fractal hierarchy theory, geometric models of BFMC tubes embedded with square, pentagonal, and hexagonal cells are constructed. Numerical simulations are carried out to systematically investigate the effects of mass, fractal dimension, and the number of sides of the embedded polygons on the axial crushing performance, and the results are compared with those of typical multi-tubes. The results indicate that, under approximately equal mass conditions, the BFMC tube can significantly enhance the specific energy absorption and the load-bearing capacity owing to its fractal hierarchical and bio-inspired configurations. Its crashworthiness increases with mass, first decreases and then rises as the fractal dimension increases, and improves further as the number of polygon sides increases, while the peak force is only weakly affected. A theoretical model for predicting the mean crushing force of BFMC tubes is developed based on the super folding element theory and is validated through numerical simulations. This study provides theoretical support and structural design guidelines for developing high performance thin-walled energy absorption structures.

To enhance the prediction accuracy of low-velocity impact performance and improve the structural design efficiency of triangular corrugated sandwich beams, this paper proposes a machine learning modeling and optimization process for the impact response of sandwich beams based on a hard-parameter-sharing multi-task learning (MTL) framework. A sample dataset is generated using finite element models, and the rationality of the models is validated against existing experimental results. Subsequently, an MTL model is trained to simultaneously predict the structural specific energy absorption (SEA), the maximum deflection of the top panel, and the initial peak load. The results show that the MTL model optimized via Bayesian optimization demonstrates strong predictive performance under a 50 J impact energy condition. The predictions align well with the finite element simulation results, with the coefficient of determination R² for all output variables in the test set exceeding 0.989, thereby validating the effectiveness and reliability of the model in response prediction and engineering optimization analysis. Parameter sensitivity analysis reveals that the core cell count and core wall thickness have the most significant influence on structural stiffness, followed by the top panel thickness, while the bottom panel thickness has a relatively minor impact. Moreover, the core wall thickness exhibits a certain saturation threshold in terms of performance enhancement. In combination with the non-dominated sorting genetic algorithm Ⅱ (NSGA-Ⅱ), multi-objective optimization analysis are conducted focusing on deformation characteristics, energy absorption performance, and comprehensive performance, and yields optimal parameter configurations that meet different engineering design requirements for sandwich beams.

To investigate the response and damage behavior of composite aero-engine blades under bird-strike events, an equivalent bird-strike testing method was proposed in which a component-level flat plate specimen was used to replace a full-scale fan blade. The method aims to reproduce the trailing-edge delamination damage observed in full-scale blades during bird strike. Bird-strike tests and corresponding numerical simulations on the plate specimens under different clamping configurations were conducted, and the impact response characteristics as well as the initiation and propagation processes of delamination were systematically analyzed for each configuration. Based on these results, a component-level equivalent test methodology capable of effectively simulating trailing-edge delamination in blade bird-strike scenarios is proposed. A baseline impact condition that induces single-side trailing-edge delamination in a representative composite laminate is identified, including impact height, impact velocity, and the bird-cut ratio (defined as the percentage of the effective impacting volume of the bird projectile relative to its total volume at the instant of impact). In addition, by comparing test and numerical results under various impact conditions, the accuracy of the numerical model is validated. Using the experimentally validated model, sensitivity analyses were performed with respect to the test parameters (impact height, impact velocity, and bird-cut ratio). The results show that, within the controllable ranges of parameter variation in the tests, the changes in key impact response metrics of the composite plate—namely the peak displacement at the upper trailing edge, the peak displacement at the lower trailing edge, and the displacement difference along the upper edge—are all less than 5% relative to the baseline condition. This study demonstrates that the proposed equivalent testing method enables a composite plate test to replicate the local displacement response and delamination pattern of a full-scale blade under bird strike, and the test outcomes exhibit good robustness.

The choice of aluminum alloys used as the interlayers significantly influences the interfacial bonding properties and dynamic impact mechanical properties of 7B53 aluminum alloy composite plates (7A52/interlayer/7A63). In this study, the influence mechanism of different aluminum alloy interlayer materials (7A01, 6061, 2024 aluminum alloy) on the interfacial metallurgical bonding quality and the dynamic mechanical behavior at high strain rates (1700−3200 s⁻¹) was systematically investigated using tensile-shear tests, Charpy impact tests, split Hopkinson pressure bar (SHPB) tests, and scanning electron microscopy (SEM). The results show that the composite plate with the 6061 interlayer exhibits the optimal interfacial bonding performance, achieving a maximum shear strength of 109.6 MPa, which is 36.5 MPa higher than that of the plate with the 7A01 interlayer (73.1 MPa). This improvement is attributed to the fact that the 6061 alloy promotes the formation of fine and uniform grains at the interface, thereby effectively strengthening the interfacial region. SHPB tests reveal that the inhomogeneous deformation of the interlayer interrupts the penetration of cracks into the 7A52 layer and promotes crack deflection along the interface. The composite plate with the 7A01 interlayer shows low strain rate sensitivity. The plate with the 6061 interlayer, while decreases in flow stress due to thermal softening within the strain rate range of 1700–2700 s⁻¹, maintains stable deformation under high-velocity impact owing to its excellent ductility. Compared to the composite plate with the 2024 interlayer, the plate with the 6061 interlayer achieves higher plastic strain while retaining relatively high yield strength. The 6061 interlayer composite plate successfully achieves an effective integration of the high toughness of 7A52 and the high strength of 7A63, providing an important theoretical basis for the design of impact-resistant protective structures for armored vehicles.

Superconductivity is defined by two fundamental criteria: zero electrical resistance and the Meissner effect. However, measuring the magnetic properties of samples under high pressure in diamond anvil cells—where sample sizes are limited to tens of micrometers and confined spatially—has long been a challenging task in high-pressure research. Magnetic measurements under high pressure using diamond anvil cells can generally be classified into four distinct methods. Among these, the modulated magnetic susceptibility measurement, which employs laboratory-fabricated multi-turn micro-coils and two lock-in amplifiers connected in series, has often yielded contradictory experimental results in the literature due to an insufficient understanding of its underlying measurement principles. In this work, starting from the experimental configuration and Faraday’s law of electromagnetic induction, we re-derive the expressions for the signal magnitude of the superconducting diamagnetic transition registered on the primary and secondary lock-in amplifiers. We obtain an expression for the signal amplification introduced by the modulated magnetic field, thereby clarifying the measurement principle of modulated magnetic susceptibility and identifying potential issues in previous studies.

The synthesis of the room-temperature superconductor LaSc₂H₂₄ represents a significant milestone in the field of superconductivity research. A central goal of subsequent studies is to lower the stabilization pressure required for hydrogen-rich superconductors, thereby establishing both theoretical foundation and technical pathway toward achieving low-pressure room-temperature superconductivity. This paper reviews recent advances in the prediction and experimental synthesis of hydride materials, with a focus on a promising strategy for realizing high-temperature superconductivity at reduced pressures—namely, H₂-molecular-typehydride. The superconducting mechanism dominated by molecular H₂ units is redefined, offering a new perspective for understanding phonon-mediated superconductivity. In H₂-molecular-type hydrides, a nearly free-electron gas behavior has been clearly observed. These delocalized electrons exhibit metallic bonding characteristics while retaining fragments of molecular hydrogen. This finding indicates that the essential condition for superconducting transition is the formation of a Fermi sea hosting Cooper pairs, rather than complete dissociation into atomic hydrogen. The generation mechanism of the free-electron gas in these materials can be effectively explained using a finite potential well model. The distinctive electronic properties of these compounds under high pressure, combined with enhanced electron-phonon coupling, establish a novel paradigm for designing low-pressure, high-temperature, and potentially room-temperature superconductors.

Recent achieved superconductivity near room temperature, especially in hydrogen-based superconductors under high pressure, have attracted broad interest. However, most systems with high superconducting critical temperature (T_c) are only stable under extremely high pressures, which limits their practical applicability. This study proposes the possibility of obtaining high-T_c superconductors at moderate pressures within the ternary Th-Y-H system. The synthesis was carried out using Th, YH₃, and NH₃BH₃ as precursors under high pressure and high temperature, applied by diamond anvil cells combined with in-situ laser heating technology. Combining with the synchrotron X-ray diffraction (XRD) measurements and theoretical studies, the main product was identified as Fm$ \overline{3} $m (Th,Y)H₁₀, with Y accounting for approximately 10%−15%. Electrical transport measurements reveal that its T_c increases by approximately 10%, compared to ThH₁₀ under similar pressure. At 144 GPa, the sample has a maximum T_c of 184 K, which remains at 170 K when decompressed to 100 GPa—approaching the highest level known for hydrides at this pressure. Measurements under an applied magnetic field further verify the superconductivity, with upper critical fields estimated at 52 and 39 T based on the WHH and GL models, respectively. These results indicate that the ternary Th-Y-H superconducting system is an outstanding candidate for high-T_c superconductors, and the crystal stability and electronic properties can be effectively controlled by reasonably introducing new element into the binary system. This work provides new insights and experimental evidences for exploring high-T_c superconducting hydrides under moderate or even low pressures.

In the search of new superconducting materials, some specific structural units are recognized as essential factors for the emergence of superconductivity, such as the CuO₂ planes in cuprates and the Fe-As layers in iron-based superconductors. In this study, we investigate the structural and transport properties of the zinc-based 112-type compound LaZn_1–δSb₂ with Zn-Sb layers at both ambient and high pressures. The LaZn_1–δSb₂ crystallizes in a tetragonal structure with a certain amount of Zn vacancies at ambient pressure. The low-temperature physical properties exhibit paramagnetic metallic behavior, with resistivity showing anisotropy behavior, and the magnetoresistance is positive at low temperatures. Meanwhile, the hole-type Hall coefficient shows significant temperature dependence, indicating that the transport behavior is dominated by multiband effects. Under high pressures, LaZn_1–δSb₂ retains its tetragonal phase while undergoing a volume compression exceeding 25%. As pressure increases, the absolute value of resistance and residual resistance ratio initially decrease and then increase. Further fitting reveals that the transport behavior under pressure remains dominated by electron-phonon scattering and shows almost no pressure dependence. Notably, no superconductivity above 2 K is observed up to the highest pressure of 50.9 GPa in this study. The absence of superconductivity in LaZn_1–δSb₂ may be related to lattice defects induced by Zn vacancies. These results can provide useful insights for the search for new superconductivity in compounds with similar structures.