Xin Li

Conventional elastic wave metamaterials are typically constrained by fixed structural configurations, which limits their ability to achieve reconfigurable and application‐specific wave manipulation. To address this challenge, this work propose a mechanical–acoustic interaction (MAI) paradigm for mechanically programmable elastic wave control, in which acoustic functionalities are reconfigured through reversible switching between bistable mechanical states. The proposed acoustic dome metamaterial (ADM) consists of modular bistable units, where the peak and valley configurations serve as two mechanically programmable states without relying on electrical, magnetic, or thermal stimuli. By spatially encoding these bistable states, the band structure and transmission characteristics of the metamaterial can be reconfigured, enabling programmable control of elastic wave propagation, attenuation, and energy localization. Numerical and experimental results demonstrate low‐frequency vibration suppression, reconfigurable waveguiding, and defect‐state‐enabled energy localization governed by mechanically encoded state patterns. Moreover, a one‐press programming strategy is introduced to improve programming efficiency and reproducibility at the system level. These findings establish MAI as a physically intuitive and scalable mechanism for elastic wave programming, offering new opportunities for reconfigurable acoustic metamaterials and intelligent acoustic devices.

力学超构材料是一类由人工微结构单元按特定序构排列而成的一类的人工材料，能够呈现常规材料难以获得的超常力学响应，如负泊松比、负等效质量密度与多稳态等。这些特性使得其在能量吸收与多功能集成方面展示出显著潜力。其中，能量耗散作为揭示力学超构材料变形演化机理的重要因素而受到广泛关注。在静/动态载荷条件下，这些力学超构材料的能量耗散主要源于弹塑性变形、断裂失效或黏弹驰豫等，是其实现特定力学性能的基础。本文从结构设计、耗能机制和力学响应三个维度，系统综述了折纸/剪纸超构材料、仿晶格型超构材料、手性超构材料以及仿生超构材料的研究进展；分析了不同结构体系的能量耗散机理与调控策略；总结了现有力学超构材料在能量耗散方面存在的关键问题; 提出了一些值得进一步深入研究的科学问题。

Multistable mechanical metamaterials have broad application prospects in various fields due to their unique configuration transformation ability, such as energy absorption, shape reconstruction, soft actuator design, mechanical storage, and logic operation. Currently, the steady‐state transition mechanisms for most multistable mechanical metamaterials rely on translational displacement input, while the rotational input mechanisms are rarely studied. Here, a curved beam snap‐fit structure is proposed to realize the multistable transition of metamaterials under rotational load. Their mechanical characteristics and influencing factors are discussed in detail through theoretical analysis, numerical simulation, and experimental verification. In addition, related rotational multistable mechanical metamaterials prototypes are designed. Their potential applications in the fields of energy absorption or robotics are demonstrated, which opens up new ideas and directions for the multifunctional applications of mechanical metamaterials.

In the current paper, the dynamic mechanical properties of sustainable lightweight aggregate concrete (SLAC) were numerically studied with a newly developed mesoscopic model. In the model, a fissure-based filling method was utilized for placing spherical aggregates, in which the aggregate geometric data were collected from specimen cross-profiles. The interfacial transition zone (ITZ) was also created in the meso-scale finite element model. The model was then utilized to simulate the Split Hopkinson Pressure Bar (SHPB) test of SLAC. The results indicated that the waveforms, dynamic compression strength, and strain rate effects obtained from the simulation closely matched the experimental ones, which demonstrated the effectiveness of the established mesoscopic model. The parametric analysis showed that the aggregate content and ITZ thickness had an important effect on the dynamic mechanical behavior of SLAC. It is believed that the current study can provide a valuable reference for the numerical study of the failure mechanism of sustainable lightweight aggregate concrete.

In this paper, we presented an extended family of Miura-ori structures with programmable multi-step deformation via arraying and mirroring. We found that there is a competitive relationship between thickness gradient and structural gradient for these origami structures. Furthermore, we demonstrate that the multi-step deformation can be designed by altering the geometrical parametric and the order of these origami structures and the number of deformation stages will change with the change of the thickness gradient. Therefore, the current study can be used to construct novel origami metamaterials for engineering applications, such as energy absorbers for both light and heavy impacts.

Magnesium and its alloys have been widely studied as absorbable coronary stent materials. However, the rapid corrosion rate in the intravascular environment inhibits the application of magnesium-based stents. In order to endow magnesium-based stent with appropriate degradation rate and biocompatibility, a hydrophobic layer was constructed by in situ cyclic grafting 4,4′-diphenylmethane diisocyanate and aminopropyl-terminated polydimethylsiloxane on pure magnesium. SEM-EDS, X-ray photoelectron spectroscopy and water contact angle were detected to analyze the chemical composition of the layer. The amino groups were confirmed to be introduced on the surface which provide a platform for subsequent modification. The contact angle value of the modified surface is 132.1°, indicating a hydrophilic surface. The electrochemical measurements and immersion tests demonstrated that the hydrophobic layer significantly improved the anti-corrosion ability of the substrate. Besides, the biocompatibility of the hydrophobic surface was examined by platelet adhesion, cytocompatibility in vitro and subcutaneous implantation in vivo. Immunological and histological results indicated that the hydrophobic layer had excellent biocompatibility. Therefore, the presented study might be a promising method for the surface modification of biomedical magnesium-based stent.

In this paper, the mechanical properties of Nomex® paper coated with resin and composite Nomex® honeycomb sandwich structures (CNHSS) were obtained by tensile tests and flatwise tests respectively. The fundamental mechanical properties of the Nomex® paper were used as input materials parameters of finite element model generated at meso-scale level for the CNHSS, and the mechanical properties of CNHSSs were used to validate the numerical results. Based on the test and numerical results, the theoretical equations were modified to predict the flatwise compressive buckling strength and modulus of the CNHSS. The numerical and theoretical results clearly revealed that the CNHSS had two flatwise compressive elastic moduli. However, the flatwise test can only capture the second flatwise compressive elastic modulus due to manufacturing geometric defects of the cell walls. The numerical and test results showed that the manufacturing geometric defects of the cell walls showed little influence on the ultimate flatwise compressive strength. And the modified equation can predict the flatwise compressive buckling strength and modulus of the CNHSS with sufficient accuracy.