Taking the quenched and tempered Cr-Ni-Mo alloy steel for brake discs of high-speed trains as the research object，the morphology of the secondary phase is observed and the size is measured by transmission electron microscopy，and the secondary phase is identified by energy spectrum analysis and electron diffraction；the principle of full-field strain measurement by geometric phase analysis （GPA） is explained in detail，it is proposed to use the geometric phase analysis to study the matching relationship in a certain direction at the interface between the matrix and the secondary phase through the bicrystal electron diffraction pattern obtained by the Fourier transform of high-resolution transmission electron microscopy （HRTEM） images of the matrix and the secondary phase. The results show that the secondary phase of Cr-Ni-Mo alloy steel used in brake discs for high-speed trains is mainly in the form of rods，and there are a small amount of secondary phase with small size and approximately round shape；the energy spectrum analysis combined and the electron diffraction method shows that the secondary phase with approximately round shape and small size particles is the Mn-containing M₂₃C₆ carbides；the strain fields in the x，xy and y directions at the interface between the matrix and the secondary phase M₂₃C₆ is obtained by geometric phase analysis，the matching relationship between matrix \left(\mathrm{1}\overline{\mathrm{1}}\overline{\mathrm{2}}\right) crystal planes and the secondary phase M₂₃C₆\left(\overline{\mathrm{1}}\mathrm{1}\overline{\mathrm{3}}\right) crystal planes is determined to be semi-coherent.

Al₂O₃ aerogels has been used as insulating materials in the high-temperature areas due to the excellent high-temperature resistance， especially at the temperatures above 1000 ℃. But the hydrophilicity of Al₂O₃ aerogels makes it easy to absorb water steam， damaging the skeleton and the thermal insulating performance. In this work， a polyvinyltrimethoxysilane （PVTMS） hydrocarbon chain polymer is synthesized with vinyltrimethoxysilane （VTMS） as the raw material to solve above problems. Then Al-polyvinyltrimethoxysilane aerogel （AlPVSA） is prepared by in-situ polymerization using PVTMS and Al（NO₃）₃·9H₂O as precursors. The polyvinyl chain is introduced into the Al₂O₃ skeleton， and the transformation from hydrophilicity to hydrophobicity is realized by adjusting the content of organic components， where the maximum contact angle is up to 136.8°. The transformation mechanism is further studied based on the surface energy and roughness. The mechanical properties of AlPVSA are improved by participating in the network-formation of organic components， and the compression modulus is maximized to 3.9 MPa when n（PVTMS/Al）=1. AlPVSA with high content silicon-polyvinyl chain is easy to form mullite phase after being heated at 1200 ℃， which lead to higher linear shrinkage （the maximum is 53.8%） and destruction of microstructure，resulting in thermal stability decrease.

To address the application demands of aerospace engines for polyimide composite materials， the preparation and properties of polyimide-sized carbon fiber-reinforced polyimide composites are investigated. By utilizing triethylamine to saltify polyamic acid for water solubility， a water-based polyimide sizing agent is successfully developed. Carbon fiber is sized with polyimide sizing agent. A preparation process is established for waterborne polyimide-sized carbon fiber. The preparation and characterization are completed for polyimide composites reinforced with polyimide-sized carbon fiber. The composite shows good internal quality. Its interlaminar shear strength reaches 120 MPa， and the glass transition temperature is 426 ℃. The mass loss ratio is only 5.90% after thermal aging at 400 ℃ for 100 h. The composite exhibits excellent temperature resistance and interfacial performance.

In order to study the influence of edge delamination defects on the static and fatigue performance of the typical plies of composite blades， the static and fatigue performance of smooth and two kinds of typical composite delamination layers are determined， and the influence of edge delamination defects on static performance and fatigue performance is analysed through SEM analysis. The results show that the static strength， tensile modulus and fatigue limit strength of 4 mm initial lamination defect declined by 0.4%，1.2% and 0.6% respectively due to the existence of initial edge delamination. The static strength， tensile modulus and fatigue ultimate strength of 6 mm initial delamination defect declined by 8.3%， 1.8% and 5.9% respectively due to the existence of initial edge delamination. Owing to the existence of initial edge delamination， the delamination phenomenon is more obvious. Consequently， delamination defects have adverse effects on the static properties and fatigue strength of the typical lamination of composite blades， and the static properties and fatigue strength decline sharply with the delamination defect size.

The issues of fiber bridging，crack deflection，and interfacial debonding during the fracture process of long fiber reinforced titanium matrix composites are one of the key concerns in the industry. In this work，the crack propagation behavior， fracture characteristics， and fiber bridging effect of SiC_f/TC17 composites under three-point bending fatigue are investigated. The results show that the fatigue crack propagation curve morphology of SiC_f/TC17 composites varies significantly under different stress ratios. When the stress ratio R is high，crack arrest occurs after the crack propagates for a certain distance. The trend of crack propagation rate varies under different stress ratios：at R=0.1，the overall propagation rate shows a continuous increasing trend；at R=0.3，the change in propagation rate tends to gradually decrease；at R=0.5，the propagation rate exhibits an overall continuous decreasing trend. The fatigue fracture surface morphology of the material is characterized by an uneven feature，consisting of many different shapes of fracture small planes，with obvious uneven height differences between adjacent small planes. A large number of fibers are in a pulled-out state on the fracture surface， and the fibers exhibit different failure modes during crack propagation. During the fatigue fracture process of materials，the crack deflects to a certain extent when bypassing the fibers. The debonding zone at the fiber/matrix interface extends longitudinally along the fibers，and bridging fibers show secondary fracture. The fiber/matrix debonding occurs at the interface between the matrix and the C coating.

Kelp is one of the most common large macroalgae in the ocean. Its presence poses a risk of propeller entanglement for ships， deep-sea exploration equipment， and other such assets. During its growth phase， it can be used as a coastal protection material， and after harvesting， it serves as a raw material for food， chemical industry， and other sectors. Therefore， there is an urgent need to conduct hydrodynamic analysis and mechanical research on its damage process. However， there is a lack of accurate mechanical models in relevant studies. In this paper， key mechanical parameters of fresh and mature kelp were measured through experiments. By adopting the method of combining elasto-plastic constitutive model with principal stress failure， a mechanical model for fresh kelp is established based on the ANSYS/LS-DYNA software. The results show that： the shear failure process of kelp is characterized by a transition from local progressive tearing to sudden fracture； comparison between verification tests and simulations reveals a maximum error of 8.248%； elastic modulus， yield strength， tangent modulus， tensile strength， and shear strength exhibit non-linear growth with increasing loading rate， showing a significant strain rate effect； elastic modulus， tensile strength， Poisson's ratio， and static friction coefficient are the key parameters influencing the kelp mechanical model； through application range analysis， the ultimate tensile strength of kelp is 2.445 MPa， and its ultimate shear strength is 0.693 MPa. The kelp mechanical model established by integrating loading rate， elasto-plastic constitutive model， and principal stress failure method provides a certain theoretical basis for research related to the mechanical properties of kelp.

Metalized thin film capacitors find diverse applications in hybrid electric vehicles， photovoltaic power generation， and ship-borne weapons due to their high-rate charge-discharge behavior. Improving the energy density of thin-film dielectric materials is crucial for advancing the electronic power industry. Here， a three-dimensional cross-linked network structure composite dielectric film-coPVDF/BST has been prepared by modifying a PVDF-based polymer， introducing high dielectric ceramic fillers， and cross-linking molding. The results demonstrate that the 3D cross-linked network structure effectively improves filler distribution uniformity， leading to a maximum breakdown strength of 424 MV/m and an enhancement in the modulus. Furthermore， the incorporation of ceramic fillers substantially increases the dielectric constant， resulting in an energy storage density of 10.4 J/cm³. This study provides design ideas for new metallized film capacitors and establishes a theoretical basis for the development of thin-film capacitors.

Zinc metal has shown considerable potential for cardiovascular and orthopedic applications due to its excellent biocompatibility and suitable biodegradation properties. However， the high initial release of Zn²⁺ triggers a severe immune response which leads to cytotoxicity， limiting its further clinical applications. In this paper， epigallocatechin gallate/metal ion （EGCG/Zn， EGCG/Mg， EGCG/Ca） based coatings are developed on pure zinc surfaces and the coating structure， degradation properties， antimicrobial properties and biocompatibility are investigated. The results show that the three coatings have good binding ability. Among them， EGCG/Mg provides optimal corrosion resistance and significantly reduces the degradation rate of the samples， while EGCG/Ca effectively promotes the formation of hydroxyapatite with optimal mineralization ability， and the EGCG coatings effectively inhibit the initial large release of Zn²⁺ and exhibit superior antimicrobial properties and good biocompatibility. This study further provides new ideas for the development of novel green chemical conversion coatings for zinc and zinc alloys.

Hydrogel is a flexible material with a high water content， excellent biocompatibility， and adjustable mechanical properties， making it an ideal choice for constructing high-performance， flexible sensors. The Hofmeister effect can alter the aggregation state of hydrogel molecular chains through various ionic action mechanisms without the need for complex chemical modifications. This enables synergistic optimization of hydrogel mechanical properties and electrical conductivity， thereby meeting the need for high-sensitivity detection in complex environments. Furthermore， the Hofmeister effect opens up a novel research avenue for the development of environmentally stable hydrogel sensors. Consequently， hydrogel flexible sensors based on the Hofmeister effect demonstrate significant potential for application in the field of smart electronic devices. This review offers a comprehensive review of the mechanisms by which the Hofmeister effect regulates hydrogels， summarizing its impact on the regulation of their mechanical properties， electrical conductivity， environmental stability， and biocompatibility. Additionally， it explores the applications of hydrogel flexible sensors based on the Hofmeister effect. It is concluded that the development of hydrogel flexible sensors modulated by the Hofmeister effect is a pivotal research direction for the future， aiming to provide a theoretical foundation and practical guidance for the further advancement of hydrogel flexible strain sensors.

Modern lifestyles are associated with significant public health concerns， including sedentary behavior and sleep disorders. Flexible wearable intelligent materials， characterized by excellent biocompatibility and continuous signal acquisition capabilities， are becoming a pivotal technology for the precise 24 h monitoring of physical behaviors （e.g.， activity， sedentariness， and sleep）. This review aims to dissect the current research landscape in this field， from theoretical foundations to engineering applications. It first explores the use of flexible electronic interfaces in physical activity monitoring， highlighting how material innovations have enabled the expansion from macroscopic biomechanical sensing to microscopic metabolite tracking. The role of these materials in identifying sedentary behaviors is then analyzed， focusing on high-sensitivity designs for capturing postural transitions and assessing physiological load. For sleep health， the discussion centers on unobtrusive material systems for long-term monitoring of respiratory and sleep rhythms. Furthermore， to support the extended operation of such wearable devices， this review synthesizes advanced self-powering and energy storage solutions， such as triboelectric nanogenerators， photovoltaics， and biofuel cells. Persistent challenges are identified， including the lack of standardized validation， limited battery life， and insufficient understanding of the complex correlations between behavior and physiology. Future progress is expected to depend on the convergence of material innovation， multimodal sensor fusion， optimized artificial intelligence algorithms， and large-scale clinical trials， ultimately contributing to a comprehensive smart health management ecosystem.