Applied Mechanics and Materials Vols. 217-219

Abstract: This paper presents the results of experimental tests and numerical analyses concerning the influence of repeated cyclic loading and reinforcement confinement on bond between steel rebar and concrete. Experimental tests of push-pull type were carried out at the Politecnico di Milano on concrete specimens provided with a steel cage of longitudinal bars and stirrups, and reinforced with a single steel rebar. The experimental tests were conducted under monotonic and repeated loading history. Bond strength degradation was observed due to repeated cyclic loading. Detailed three-dimensional finite element models of the specimens were developed to reproduce laboratory tests and parametric analyses were performed to provide a better understanding of the experimental results. The numerical analyses showed good agreement with the experimental results and confirmed that the applied repeated loading history caused significant bond deterioration. High values of reinforcement confinement enhanced bond strength and delayed the onset of bond deterioration.

Abstract: Do tests to study anti-penetration performance of ceramic multi-layer composite medium structure with simulation method of a 1:5 shrinking model and analyze its mechanism. The result shows that ceramic composite layers, which are composed by glass reinforced plastic materials and ceramic materials, obviously consume quality and kinetic energy of penetrating shot body. And the smaller biting angle of shot body is, the more serious damage of structure will be.

Abstract: Based on static and dynamic compression tests of plain concrete, SiO2(NS) concrete, CaCO3(NC) concrete and composite concrete with different NS-NC contents, dynamics performance of nano-concrete materials is analyzed to study influence factors and find the optimum nano-content.

Abstract: In order to restrain the recombination of electron-hole pairs of photocatalysis and induce the absorption spectra to shift to the visible region, TiO₂ nanowire arrays doped with different transition metal ions were prepared by sol-electrophoresis deposition method. The photocatalytic activities of all doped nanowire arrays (M/TiO₂) were measured under visible light. Transition metal ions (Fe³⁺, Zn²⁺, Cr³⁺ and Cu²⁺) were chosen as doping ions. The best doping content of each ion was found via photocatalytic degradation of methyl orange solution under visible light, there are 0.5 wt% Fe³⁺，1.0 wt% Zn²⁺，0.5 wt% Cr³⁺ and 0.25 wt% Cu²⁺ respectively. Under the best doping content of each ion for M/TiO₂ nano-arrays, the photocatalytic activities are Fe>Zn>Cu>Cr. The effect mechanisms are discussed from different views of doped semiconductor and surface oxygen absorption.

Abstract: Fabrication of nanofibres has become a growing area of research because of their unique properties (i.e. smaller fibre diameter and higher surface area) and potential applications in various fields such as filtration, composites and biomedical applications. The mechanism of nanofibre fabrication by meltblowing process with the injection of different fluids (such as air and water) has been investigated in this paper. In the meltblowing equipment the fluids were injected at a vent port along the extrusion barrel, for the fabrication of nanofibres. The injection of water resulted in better fibre morphology compared to the injection of air. Nanofibres were fabricated by the drafting action of the high-velocity flow of the heated air and the steam in the extruder. The fibres collected were straight prior to the fluid injection and coiled fibres were collected with the injection of fluids. Three types of fibres such as ribbon shaped, fused and branched fibres were obtained in addition to the circular fibres.

Abstract: High luminescent intensity micro – nanometer Ca_0.69Sr_0.23(P_xMo_y)O₄:0.05Eu³⁺ phosphor were synthesized by an innovative co precipitation-melted-salt (CPMS) method, Using Eu₂O₃, Ca(OH)₂, SrCO₃, HNO₃, (NH₄)₆Mo₇O₂₄4H₂O, (NH₄)₂HPO₄ and inorganic flux as raw materials, room temperature co precipitation and Melted-salt-calcination at 800°C. The results show that the Ca_0.69Sr_0.23(P_xMo_y)O₄:0.05Eu³⁺ emits strong 615 nm red light ( exited by 285 nm UV), the luminescent intensity of phosphor is the highest when x / y = 1. The size of the dispersed phosphor is about 1.0 μm. The phosphors have great potential applied as photon conversion materials in Si-solar photovoltaic system and devices.

Abstract: The ultrasonic-assisted single-grit grinding device is designed which can be used to efficiently simulate grinding process, and the comparative tests of single-grit ultrasonic grinding are carried out between Nano-ZrO₂ ceramics and ZTA ceramics under different grinding depth. The experimental results show that the bigger the scratch depth was, the greater damage degree of material was, nano-ZrO₂ ceramics’ grooves is smoother than that of ZTA ceramics and the damage of its material is minor; ultrasonic vibration broadens the range of plastic cutting of Nano-ZrO₂ ceramics in some degree. The experimental phenomena also show that the rolling role of abrasive particle can be conducive to material plastic deformation.

Abstract: The methods for wear resistance testing is described and the experimental results for the dependence of the massive wear, wear speed, intensity of wear and wear resistance on the friction road and the time of a contact interaction are obtained. A testing micromanipulator with piezo actuators for measuring the roughness of the surface layer is developed. A methodology for thermographic testing and experimental results for wear and temperature changes in the contact by the wear process of the coatings under dry friction and abrasion is obtained

Abstract: The in-plane thermoelectric generator (TEG) was ingeniously designed when the thermal gas flowed over the carbon nanotube (CNT) membrane at the modest speed of a few meters per second. It was composed of the glass substrate, aurum electrodes and CNT membrane synthesized by a floating catalyst chemical vapor deposition method. In the air under atmospheric pressure, the experimental results showed that the maximal output voltage could reach 1.7 mV. It related not only with the temperature difference between the hot-side and cold-side, but also the temperature gradient of the CNT membrane which was closely dependent on the velocity and temperature of the gas flow. The multi-physical power mechanism was applied to interpret the energy conversion, which included the coupling relation of the fluid dynamics, heat transmission and Seebeck effect. This novel method could effectively enhance the output voltage, extend the applied range of TEG and had a fine prospect.

Abstract: Under the conditions of the presence of surfactants and ultrasonication, the use of different cerium salt, respectively, with oxalic acid under solid state chemistry reactions, the synthesis of nano-rare earth metal complexes of cerium oxalate crystals was formed. The solid phase was characterized by powder X-ray diffraction (XRD) and electron diffraction (ED). The particle size, its distribution, and morphology of the prepared nanocrystallite were observed by transmission electron microscopy (TEM). The results show that particle sizes are relatively uniform, the morphology of the crystal is spherical, the average particle diameter is about 40 nm, and the yield rate is approximately 91.6%. Furthermore, during the synthesis, the solid-state reaction conditions including raw materials, matching proportion of reactants, additions of inert substance, addition of trace solvents, surfactants and porphyrization time, etc, all have some influence on the morphology, particle size and size distribution of the final products. During the synthesis of the cerium oxalate nanocrystallines, the solid state reaction conditions such as changing reactant, matching proportion of reactant, adding inert substance, joining a little solvent or surface active solvent and grinding at different times may influence morphology, particle size and the size distribution of final products.