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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.

This work discusses the influence of external impact upon pouring of high strength alloyed steel into thin walled molds with external cooling and in the same molds with suspension pouring: complex impact on hardened casting. Selection of these technologies is substantiated. The casting produced in a 3D liquid glass mold was used as reference. Microstructure, fracture, and mechanical proports of metal were analyzed at regular (+20°C) and higher (+350°C) temperatures. The most dense and homogeneous structure and fracture were obtained for the casting upon complex impact. It has been established that the main advantage of the proposed technologies is improvement of homogeneity of mechanical properties across the cross section and height of castings, especially of plastic properties and impact viscosity. Anisotropy of the properties across cross sections and height of experimental castings is significantly lower than in reference casting. It has been established that the external and complex impact on formed casting allows to improve its mechanical properties upon various test temperatures. The casting produced in a metal shell mold with forced cooling exhibits no significant differences of mechanical properties both across its heigh and cross section. Herewith, the strength is in average by 100 MPa higher than that of reference casting at the same high plasticity and impact viscosity.

An elastic boundary-value problem was solved for a two-layer sphere acted upon by an internal dynamic pressure generated by an explosion of a spherical explosive charge. The peculiarities of solutions for shells with an ultrathin inner metallic layer were studied. An analysis was performed to compare the static case with the dynamic one. The peculiarities of such solutions were pointed out. Taking into account the data earlier obtained by the authors, it was proved analytically and numerically that in two-layer spherical metal composite vessels, the hoop stresses in the inner layer (S 1 ) could be much higher than the stresses in the outer layer (S 2 ) if the thickness of the inner metallic layer was much smaller than that of the outer layer. An exact asymptotic ratio S 1 /S 2 for static and dynamic problems was obtained. It is shown that in such structural elements at small relative thicknesses of the metallic layer, there can be a softening region. A formula was derived, which made it possible to predict in an engineering approximation the presence or absence of a softening region. For the dynamic problem, it was found that with decreasing thickness of the inner more rigid layer, the hoop stresses in it grew in proportion to the ratio of the spherical rigidities of the materials of the inner and outer layers. This can lead, as in the static case, to the fact that the pseudo-reinforcement of the composite shell with a too thin inner fairly rigid and strong metallic layer will not only be inefficient, but also can cause a failure of the inner layer and hence of the shell as a whole under loads that are fairly safe for the composite shell without the inner pseudo-reinforcing layer.

This work mainly aims to analyze the natural vibration of the sandwich-structured cylindrical shells using a theoretical framework for the structral with a porous metal core layer. The theoretical model applies the modified thick shell theory (MTST), which includes the initial curvature effect. Designed to reduce structural weight, these shells are composed of a thick porous metal core sandwiched between thin layers of homogeneous metallic material. The comparative study has revealed the advantages of using the MTST over the classical shell theory (CST), emphasizing the limitations of the CST, particularly for large thickness structures with high-frequency modes. This combination in the free vibrational examination of sandwich porous metal shells underscores the accuracy, high reliability, and efficiency of the MTST and the theoretical approach. Furthermore, this work contributes to a deeper understanding of the evaluation and development of these structures for practical applications.

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. Graphical abstract

The heavy metals were measured in edible parts and shells of five edible bivalve species; Venerupis corrugata, Venerupis sp. , Venerupis aurea, Ruditapes decussatus, and Paratapes undulatus collected from Timsah Lake, Suez Canal, Egypt. Ruditapes decussatus showed the highest average of flesh weight and exhibited the highest accumulation averages of Mn, Ni, and Pb. Paratapes undulatus recorded the highest averages of Fe, Zn, Cu, Cd, and Co in their flesh. According to the WHO guidelines, Fe levels in the edible parts of V. corrugata , R. decussatus and P. undulatus exceed the permissible limit of 100 µg/g. In contrast, Cu and Zn metals concentrations are below the permissible limits of 30 and 1000 µg/g, respectively. The levels of Pb and Ni surpass the permissible limits (0.2 and 0.35 µg/g) in all the studied species. Meanwhile, Cd levels are below the permissible limit (0.07 µg/g) in all species, except for P. undulatus . Furthermore, P. undulatus had the highest shell weight average and the highest averages of the mineralized; Fe, Mn, Zn, Cu, Ni, Pb, and Cd. Zn recorded the highest mineralization ratio (metal shell /metal flesh ) in the shells of R. decussatus, P. undulates, and V. corrugata (11.38, 6.26, and 5.18, respectively). However, Cd and Fe showed high mineralization ratios in the shell lattices of P. undulatus (7.17, 6.22), suggesting that some bivalve species have demonstrated differential abilities to mineralize certain metals within their shells.