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As compared with homogeneous metals and alloys, cellular metals provide low density, high specific stiffness, high energy absorption and good damping, thus being interesting alternatives to employ as protection against shock and impact. Impact energy is dissipated through cell bending, buckling or fracture. The knowledge and computational modelling of the mechanical behaviour of metal foams structures is thus of great importance for real life applications. The purpose of this paper is to increase the knowledge of the differences in metallic hollow sphere structures' (MHSS) behaviour under dynamic loading, as compared with the corresponding behaviour under static loading and to determine the influence of inertia and loading rate.

Computational dynamical finite element analyses of representative volume elements (RVE) of MHSS have been performed considering varying loading rates. Partially bonded geometries are considered and the effect of the spheres' distribution is also taken into account.

The results of the numerical examples presented show that inertia plays an important role in the dynamic behaviour of this kind of energy‐absorbing structure. When compared with the corresponding values in the quasi‐static case, the effect of inertia makes the peak load higher. If the deformation rate is higher (greater than 1.39 m/s in the studied cases), the characteristic plateau usually present in compressed metal foams can vanish. For the geometries analysed, damage has a small influence on load‐deformation relations.

This paper presents and discusses differences between static and dynamic behaviour of partially bonded MHSS. There are few references in the literature covering this issue by means of numerical analysis.

Metal foams are a structural and functional composite materials that have received wide attention due to their specific structures and properties. The aim of this study is to investigate the mechanical properties of syntactic foam by using expanded silica gel with the spacer technique.

In this research paper, the vacuum casting production method was used to produce metal syntactic foams including AlSi12 and AlSi8Cu3 matrix and expanded silica gel fillers with diameters of 2–4.75 mm and 4.75–5.6 mm.

As a result of the study, it was observed that as the foam densities increased, the compressive strength values of the samples increased due to the increasing volume fraction of the metallic matrix. Samples with the AlSi12 matrix showed higher compressive strength than samples with the AlSi8Cu3 matrix.

The originality of the study is the comparison of two different main matrix alloys (AlSi12 and AlSi8Cu3) and different pores using expanded silica gel.

This paper aims to introduce a novel approach to the fabrication of photoluminescent materials by coating rare earth aluminate luminescent materials on metallic substrates and a readily manufacturable light source with robust structure in the form of photoluminescent sphere (APS).

The clean and dried stainless steel sphere was sprayed with UH 2593, a white undercoat, the luminescent coating and the weather resistance coating in chronological order.

After adhered onto the stainless steel sphere, the peaks corresponding to the N-H stretching vibrations were changed. The intensity of free N-H stretching at 3,536 cm⁻¹ dramatically decreased and the peak of hydrogen-bonded N-H stretching of PU moved to lower wavenumbers. The red shift of the infrared bands of functional groups was attributed to the strengthened hydrogen bonding. The hydrogen bonding interactions between the stainless steel substrates and the polyurethane coating endowed the APS with excellent adhesive property and also promoted the evenly distribution of the photoluminescent particles in the polymer coating matrix.

This approach can be applicable in the fabrication of the photoluminescent materials. The APS can be used as signs and guiding post in remote areas without sufficient electricity supply and in the seas and rivers with complicated hydrological conditions.

This approach has provided a method to produce tough and durable luminescent signs for remote areas and dangerous seas and explained the functional mechanism of the combined application of metallic materials and non-metallic materials.

This paper gives a bibliographical review of the finite element methods (FEMs) applied to the analysis of ceramics and glass materials. The bibliography at the end of the paper contains references to papers, conference proceedings and theses/dissertations on the subject that were published between 1977‐1998. The following topics are included: ceramics – material and mechanical properties in general, ceramic coatings and joining problems, ceramic composites, ferrites, piezoceramics, ceramic tools and machining, material processing simulations, fracture mechanics and damage, applications of ceramic/composites in engineering; glass – material and mechanical properties in general, glass fiber composites, material processing simulations, fracture mechanics and damage, and applications of glasses in engineering.

A Pitot‐static tube structure comprising, in combination, a shell having a hollow protuberance thereon, said shell having a dynamic pressure opening at the front end and a static opening at the side thereof; a partition in said shell separating an interior portion of said protuberance from the remainder of the space in said shell; a dynamic pressure duct within said shell connecting said dynamic opening with the hollow of said protuberance above said partition; a continuation duct leading from a point near the top interior of said protuberance downwardly and out of said shell; a second duct leading outward from the interior of said shell; a heating element positioned internally near the forward end of said shell adjacent said dynamic pressure duct; a second heating element positioned nearer to said protuberance; and a heat conveying member arranged to conduct heat from said second heating element to an outer wall of said protuberance.

Cobalt/gold hollow microspheres were successfully prepared through galvanic replacement in an organic solvent. The diameters of these hollow microspheres ranged from 800 nm to 1 μm. However, the surface of the hollow microsphere was very rough. Nanospikes of various lengths from about 40 to 100 nm were grown on the surface of these spheres. Initially, particles with "island-like" rough surfaces were found with the addition of 4 ml chloroauric acid (HAuCl₄). When the volume of HAuCl₄ increased from 4 to 5 ml, microspheres with a hollow structure were formed. Some broken microspheres were observed when HAuCl₄ was further increased to 6 ml. X-ray diffraction results showed a high-intensity sharp peak of gold when the HAuCl₄ in the sample increased. After the galvanic replacement reaction, the cobalt content in the sample decreased meanwhile the gold content increased. This can be seen from energy dispersive X-ray analysis spectroscopy and also evident from the thermo gravimetric analysis result. The hollow Au/Co microspheres showed two broad plasmonic peaks in the ultraviolet-visible measurement. The plasmonic peaks at longer wavelengths shifted to the near-infrared region with the addition of HAuCl₄.

This paper attempts to cover the thermal processes in syntactic metal foams. Regularshaped cubic closed‐cell structures with spherical pores are investigated by means of the finite element method. Based on the numerical modelling of the microstructure, the effective macroscopic thermal properties are evaluated. Different relative densities (0.95 ‐ 0.5) and different base materials (aluminium and iron) are considered. Furthermore, the influence of the geometry, i.e. spherical ‐ cubical for 3D and circular ‐ rectangular for 2D models, is investigated. The focus is on such cellular materials where the transport of heat is dominated by solid conduction and thermal radiation; contributions from gaseous conduction and convection are neglected.

Among the different methodologies used for performance control in precision manufacturing, the measurement of metrological test artefacts becomes very important for the characterization, optimization and performance evaluation of additive manufacturing (AM) systems. The purpose of this study is to design and manufacture several benchmark artefacts to evaluate the accuracy of the selective laser melting (SLM) manufacturing process.

Artefacts consist of different primitive features (planes, cylinders and hemispheres) on sloped planes (0°, 15°, 30°, 45°) and stair-shaped and sloped planes (from 0° to 90°, at 5° intervals), manufactured in 17-4PH stainless steel. The artefacts were measured optically by a structured light scanner to verify the geometric dimensioning and tolerancing of SLM manufacturing.

The results provide design recommendations for precision SLM manufacturing of 17-4PH parts. Regarding geometrical accuracy, it is recommended to avoid surfaces with 45° negative slopes or higher. On the other hand, the material shrinkage effect can be compensated by resizing features according to X and Y direction.

No previous work has been found that evaluates accuracy when printing inwards (pockets) and outwards (pads) geometries at different manufacturing angles using SLM. The proposed artefacts can be used to determine the manufacturing accuracy of different AM systems by resizing to fit the build envelope of the system to evaluate. Analysis of manufactured benchmark artefacts allows to determine rules for the most suitable design of the desired parts.

The purpose of this paper is to synthesize SnO₂–ZnO hollow nanofibers, study their sensing properties and introduce an attractive candidate for formaldehyde detection in practice.

Pure and SnO₂–ZnO hollow nanofibers were synthesized by electrospinning method and characterized via X-ray diffraction, field-emission scanning electron microscopy and Fourier transform infrared spectroscopy. The formaldehyde-sensing properties were investigated.

The optimum performance was obtained at 260°C by the 14 at.% SnO₂–ZnO hollow nanofiber sensor. The sensor could detect formaldehyde down to 0.1 ppm with rapid response–recovery time (4-6 s and 7-9 s, respectively), high sensitivity, good selectivity and stability. The relationship between the sensor’s sensitivity and formaldehyde concentration suggests that the adsorbed oxygen species on the sensor’s surface is O2−. The prominent sensing properties are attributed to the one dimensional hollow nanofiber structures and the promoting effects of SnO₂.

The sensor fabricated from 14 at.% SnO₂–ZnO fibers exhibits excellent formaldehyde-sensing characteristics. It can be used for formaldehyde detection in practice.

The electrospinning method is a very simple and convenient method for fabricating hollow nanofibers and the sensing material is of low cost.

To the best of the authors’ knowledge, studies on formaldehyde sensing of SnO₂–ZnO hollow nanofibers have not been reported before.