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Metal cylindrical shells are widely used to store and transport highly hazardous chemicals. The impact resistance of metal cylindrical shells under an explosive load is a concern for researchers. In this paper, an innovative failure criterion considering the time effect is proposed for metal cylindrical shells under explosive loads. Firstly, based on the maximum shear stress criterion, an innovative failure criterion containing the time effect is provided. Then, a metal cylindrical shell model is established. Next, a failure pressure equation for metal shells under an explosive load is proposed based on the innovative failure criterion. Lastly, the proposed equation is verified by numerical simulation. The results indicate the failure pressure equation for a metal cylindrical shell under an explosive load uses the finite element method. Our research is of significance for fully understanding the failure mechanism of piping and pressure vessels under impact load.

Precious metal nanoparticles are commonly used as the main active components of various catalysts. Given their high cost, limited quantity, and easy loss of catalytic activity under severe conditions, precious metals should be used in catalysts at low volumes and be protected from damaging environments. Accordingly, reducing the amount of precious metals without compromising their catalytic performance is difficult, particularly under challenging conditions. As multifunctional materials, core-shell nanoparticles are highly important owing to their wide range of applications in chemistry, physics, biology, and environmental areas. Compared with their single-component counterparts and other composites, core-shell nanoparticles offer a new active interface and a potential synergistic effect between the core and shell, making these materials highly attractive in catalytic application. On one hand, when a precious metal is used as the shell material, the catalytic activity can be greatly improved because of the increased surface area and the closed interfacial interaction between the core and the shell. On the other hand, when a precious metal is applied as the core material, the catalytic stability can be remarkably improved because of the protection conferred by the shell material. Therefore, a reasonable design of the core-shell catalyst for target applications must be developed. We summarize the latest advances in the fabrications, properties, and applications of core-shell nanoparticles in this paper. The current research trends of these core-shell catalysts are also highlighted.

The article considers one of the possible mechanisms of loading the solidity of a cylindrical metal composite high-pressure vessel (MC HPV). This mechanism manifests itself as delamination of a thin-walled metal shell (liner) from a more rigid composite shell causing local buckling. A similar effect can be detected in the manufacturing process of MC HPV, when the composite shell is formed by winding with tension a carbon fiber-reinforced plastic tape on the liner. Pressure transfer from the composite shell to the liner is carried out by the method of temperature analogy, that is, by cooling the composite shell, thermally insulated from the liner. To solve the problem of externally confined liner local buckling a software-based approach is proposed, which is based on three points: the introduction of local technological deviations inherent in actual structures, the determination of the general stress-strain state, and a real-time deforming. The approach is implemented in the LS-DYNA software package in a dynamic formulation using solid finite elements. In the MC HPV deformation model, composite shell is considered to be elastic, multilayer, and liner-to be elastoplastic, isotropic. The contact between the liner and the composite shell is unilateral, normal; there are no tangent interactions. Technological deviations are presented in the form of cutouts in the liner and the composite shell on the cylindrical part of the vessel with the dimensions of permissible defects.

To ensure safe and stable operation of electronic components and functional structural components of automotive pressure sensors under complex working conditions, they shall be sealed and encapsulated. In this paper, the automotive pressure sensors are encapsulated with metal shell crimping-formed and sealing method. The process of crimping-formed and sealing is simulated and analyzed. The structure of crimping-formed and sealing is optimized with response surface method. The reliability of its encapsulation is verified through experiment. The results show that the crimping-formed and sealing process can effectively improve the long-term reliability of the sensors by forming a sealing interface through metal plastic deformation, and provide a new solution for the encapsulation of automotive pressure sensors.

Concentrating active Pt atoms in the outer layers of electrocatalysts is a very effective approach to greatly reduce the Pt loading without compromising the electrocatalytic performance and the total electrochemically active surface area (ECSA) for the oxygen reduction reaction (ORR) in hydrogen-based proton-exchange membrane fuel cells. Accordingly, a facile, low-cost, and hydrogen-assisted two-step method is developed in this work, to massively prepare carbon-supported uniform, small-sized, and surfactant-free Pd nanoparticles (NPs) with ultrathin ∼3-atomic-layer Pt shells (Pd@Pt 3L NPs/C). Comprehensive physicochemical characterizations, electrochemical analyses, fuel cell tests, and density functional theory calculations reveal that, benefiting from the ultrathin Pt-shell nanostructure as well as the resulting ligand and geometric effects, Pd@Pt 3L NPs/C exhibits not only significantly enhanced ECSA, electrocatalytic activity, and noble-metal (NM) utilization compared to commercial Pt/C, showing 81.24 m 2 /g Pt , 0.710 mA/cm 2 , and 352/577 mA/mg NM/Pt in ECSA, area-, and NM-/Pt-mass-specific activity, respectively; but also a much better electrochemical stability during the 10,000-cycle accelerated degradation test. More importantly, the corresponding 25-cm 2 H 2 -air/O 2 fuel cell with the low cathodic Pt loading of ∼ 0.152 mg Pt /cm 2 geo achieves the high power density of 0.962/1.261 W/cm 2 geo at the current density of only 1,600 mA/cm 2 geo , which is much higher than that for the commercial Pt/C. This work not only develops a high-performance and practical Pt-based ORR electrocatalyst, but also provides a scalable preparation method for fabricating the ultrathin Pt-shell nanostructure, which can be further expanded to other metal shells for other energy-conversion applications.

Application of phase change materials (PCMs)-based thermal management technology in flexible electronic devices has been inhibited due to the leakage and strong rigidity of PCMs. A novel flexible composite PCMs with ultrahigh extensibility was developed in this paper. Concretely, a kind of paraffin@copper (PA@Cu) microcapsule with paraffin as core and nano-Cu particle as “flexible” metal shell was prepared by a simple Pickering emulsion method in an aqueous medium. The encapsulation ratio of paraffin reached 98wt%. Then the PA@Cu microcapsules were introduced into uncured liquid silicone to fabricate flexible composite PCMs (PA@Cu/SE). SEM results demonstrated that the microcapsules were tightly and uniformly wrapped in the three-dimensional network structure of silicone elastomer matrix. Owing to the good compatibility of PA@Cu with the polymer elastomer and a barrier for the melted PA provided by the “flexible” nano-Cu shell, the resulting composite PCMs present superior flexibility and thermal reliability. Tensile tests showed that the flexible composites with a relative higher loading of PA@Cu (40wt%) exhibit outstandingly larger extensibility (> 730%) than many reported literatures. In addition, the composites presenting superior thermal protection for biological tissue make them well-suited for thermal management in wearable electronics.

Detonation and fragmentation of ductile cylindrical metal shells is a complicated physical phenomenon of material and structural fracture under a high strain rate and high-speed impact. In this article, the smoothed particle hydrodynamics (SPH) numerical model is adopted to study this problem. The model’s reliability is initially tested by comparing the simulation findings with experimental data, and it shows that different fracture modes of cylindrical shells can be obtained by using the same model with a unified constitutive model and failure parameters. By using this model to analyze the explosive fracture process of the cylindrical shells at various detonation pressures, it shows that when the detonation pressure decreases, the cylindrical metal shell fracture changes from a pure shear to tensile–shear mixed fracture. When the detonation pressure is above 31 GPA, a pure shear fracture appears in the shell during the loading stage of shell expansion, and the crack has an angle of 45° or 135° from the radial direction. When the pressure is reduced to 23 GPA, the fracture mode changes to tension–shear mixing, and the proportion of tensile cracks is about one-sixth of the shell fracture. With the explosion pressure reduced to 13 GPA, the proportion of tensile cracks is increased to about one-half of the shell fracture. Finally, the failure mechanism of the different fracture modes was analyzed under different detonation pressures by studying the stress and strain curves in the shells.

The addition of oxidizing agents in the explosives could enhance the burning rate and the reaction degree of aluminum powder due to the increase of oxidizing gas content in the detonation products. Therefore, it affects the metal acceleration ability of the explosive. The current study is concerned with investigating the metal acceleration ability of the CL-20-based aluminized explosive containing oxidizer affecting metal shells through standard cylinder tests. The diameter of the cylinder is 50 mm. An all-fiber displacement interferometer system with a photon Doppler velocimeter took into account the continuous measuring of the cylinder wall velocity over time. The detonation velocity was calculated by the velocity jump time interval of the cylinder wall. BKW equation was applied to calculate the detonation pressure. The effects of oxidizer on the ignition time and the reaction degree of aluminum powder were analyzed by replacing aluminum powder with lithium fluoride for comparison. According to the cylinder wall velocity energy source, empirical formula about explosive composition and the cylinder wall kinetic energy was fitted. The results show that CL-20-based aluminized explosive detonation velocity and aluminum content is linearly correlated, and oxidizer-containing explosives detonation velocity can be equivalent to oxidizer-free explosives within a certain margin of error. With the addition of oxidizer, detonation pressure, and the base explosive content no longer show the same increasing and decreasing relationship. When the aluminum content is 5% and 30%, the ignition time of aluminum powder is 4.81μs and 1.66μs earlier respectively. When the aluminum content is 5%, the reaction degree of aluminum powder reaches 1. The aluminum powder reaction rate for oxidizer-containing explosives and oxidizer-free explosives is mutually fast and slow. When the aluminum content is 30%, aluminum powder reaction degree and aluminum powder reaction rate for oxidizer-containing explosives are higher than that of oxidizer-free explosives throughout. Based on the fitted relationship equation, it is predicted that the maximum value of kinetic energy of the cylinder wall is obtained at 10% aluminum powder content with 10% oxidizer.

Extended X‐ray absorption fine structure (EXAFS) is a comprehensive and usable method for characterizing the structures of various materials, including radioactive and nuclear materials. Unceasing discussions about the interpretation of EXAFS results for actinide nanoparticles (NPs) or colloids were still present during the last decade. In this study, new experimental data for PuO2 and CeO2 NPs with different average sizes were compared with published data on AnO2 NPs that highlight the best fit and interpretation of the structural data. In terms of the structure, PuO2, CeO2, ThO2, and UO2 NPs exhibit similar behaviors. Only ThO2 NPs have a more disordered and even partly amorphous structure, which results in EXAFS characteristics. The proposed new core‐shell model for NPs with calculated effective coordination number perfectly fits the results of the variations in a metal–metal shell with a decrease in NP size. New experimental EXAFS results for PuO2 and CeO2 nanoparticles in the size range of 2 nm were compared with published data for other lanthanide and actinide dioxides. A conceptual core‐shell model with a calculated effective coordination number is proposed to fit the changes in EXAFS.

Since World War I, considerable amounts of warfare materials have been dumped at seas worldwide. After more than 70 years of resting on the seabed, reports suggest that the metal shells of these munitions are corroding, such that explosive chemicals leak out and distribute in the marine environment. Explosives such as TNT (2,4,6-trinitrotoluene) and its derivatives are known for their toxicity and carcinogenicity, thereby posing a threat to the marine environment. Toxicity studies suggest that chemical components of munitions are unlikely to cause acute toxicity to marine organisms. However, there is increasing evidence that they can have sublethal and chronic effects in aquatic biota, especially in organisms that live directly on the sea floor or in subsurface substrates. Moreover, munition-dumping sites could serve as nursery habitats for young biota species, demanding special emphasis on all kinds of developing juvenile marine animals. Unfortunately, these chemicals may also enter the marine food chain and directly affect human health upon consuming contaminated seafood. While uptake and accumulation of toxic munition compounds in marine seafood species such as mussels and fish have already been shown, a reliable risk assessment for the human seafood consumer and the marine ecosphere is lacking and has not been performed until now. In this review, we compile the first data and landmarks for a reliable risk assessment for humans who consume seafood contaminated with munition compounds. We hereby follow the general guidelines for a toxicological risk assessment of food as suggested by authorities.