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Composite sandwich structures are widely used in the aerospace field due to their advantages of high strength, lightweight, and fatigue resistance. However, these structures are prone to damage with very-low-energy impacts. In order to improve the impact resistance of aircraft skin structure, a low-velocity impact resistance of sandwich structure specimens was tested by means of drop hammer impact, and the impact damage area was scanned by ultrasonic C-scan, and obtains the impact damage of specimens with different impact energies and different ply sequences. Combined with the Hashin failure criterion, the finite element equivalent model of composite sandwich structure under low-velocity impact was established. The errors between the simulation results and the C-scan results of the test piece were less than 10%, in which the experimental measurements and numerical predictions were in close agreement. Finally, the finite element equivalent model was applied to optimize the application of model sandwich, which was used for fuselage skin of a certain electric aircraft. The total thickness of the laminate structure remains unchanged before and after optimization, but the impact resistance was significantly enhanced. The ±45° lay-up was beneficial for the structure to absorb the impact energy.

Anisotropic materials featured with ordered arrangement of sub‐structures are ubiquitous in living organisms, and possess rapidly increasing relevance to emerging technologies in smart materials, soft robotics, flexible displays, and biomedicines. However, the integration and programming of multiple properties into anisotropic materials, which endow themselves with extended intrinsic capabilities and utilities, still remain a challenge. Herein, we report a multi‐programmable anisotropic material by embedding ferromagnetic two‐dimensional nanoplates into hydrogel matrix. The nanoplate exhibits not only a disc‐like non‐isotropic shape, but also an intrinsic easy magnetization axis perpendicular to its basal plane. Using a directional external magnetic field, we can precisely control the orientation of nanoplates inside hydrogel precursor solution and then fix them via photolithographic polymerization, leading to the fabrication of anisotropic hydrogel with on‐demand ordered alignment of nanoplates. Such deliberate arrangement of nanoplates brings in extraordinary optical properties due to birefringence, enabling us to encrypt pattern information into hydrogel materials that is only visible under polarized light. Soft actuators with programmable optical, mechanical and magnetic properties are engineered, which allow to encode diverse deformation and locomotion modes, determine the actuation sites, and monitor the sub‐structural anisotropy all simultaneously, opening new avenues for the design of anisotropic soft materials. [ABSTRACT FROM AUTHOR]

This study focuses on incorporating liquid molecules, different from the bulk solution, into the immobilized enzyme carrier to regulate the distribution effect and diffusion‐limiting impact of the carrier's microenvironment for substrates, which generally is difficult to achieve due to the instability of the materials with liquid inclusions. A freestanding liquid‐holding particle carrier, with bi‐component hydrophobic ionic liquid gel microspheres with poly (glycidyl methacrylate) as the network and 1‐butyl‐3‐methylimidazolium hexafluorophosphate as the dispersing medium, is proposed, which is stable in air aqueous solution, and can extract proteins and organic small molecules into its interior due to the mobility of its dispersing medium. Horseradish peroxidase is covalently immobilized into the microspheres, forming a liquid compartment enzyme microreactor. The microreactor exhibits superior stability, enzymatic activity, and catalytic performance for Basic Orange II degradation compared to free enzyme and liquid‐free immobilized enzymes. This is attributed to the biocompatibility of the ionic liquid, its role in substrate enrichment in its interior, and its rapid mass transfer capability. This contribution shows the effectiveness of regulating the carrier's microenvironment with liquid molecules, offering fresh perspectives and strategies for enzyme technology. [ABSTRACT FROM AUTHOR]

This review discusses the progress of research on sulfonated poly(ether ether ketone) (SPEEK) and its composite membranes in proton exchange membrane fuel cells (PEMFCs). SPEEK is a promising material for replacing traditional perfluorosulfonic acid membranes due to its excellent thermal stability, mechanical property, and tunable proton conductivity. By adjusting the degree of sulfonation (DS) of SPEEK, the hydrophilicity and proton conductivity of the membrane can be controlled, while also balancing its mechanical, thermal, and chemical stability. Researchers have developed various composite membranes by combining SPEEK with a range of organic and inorganic materials, such as polybenzimidazole (PBI), fluoropolymers, and silica, to enhance the mechanical, chemical, and thermal stability of the membranes, while reducing fuel permeability and improving the overall performance of the fuel cell. Despite the significant potential of SPEEK and its composite membranes in PEMFCs, there are still challenges and room for improvement, including proton conductivity, chemical stability, cost-effectiveness, and environmental impact assessments. [ABSTRACT FROM AUTHOR]