Applied Mechanics and Materials Vol. 251

Abstract: Increasing the axle loads is becoming one of the solutions to meet the increasing demands of transportation, which makes the wheel bear larger heat loads and suffer worse heat damage. Therefore, it is necessary to simulate the thermal stress of the 30 t axle-load wheel and reveal the influence law between the braking power and the thermal damage in order to support the design of operating and braking. And a new method that simulates the braking working conditions based on the results of the heat treatment is put forward. According to the thermal elasto-plastic theory, this paper simulates the distribution of the residual stress generated in the heat treatment process and the thermal stress of the residual deforming wheels using the time-history of the thermal braking power on Datong-Qinhuangdao railway, which is based on the real working conditions. The paper proves that the new 30 t wheel plate will bear larger thermal and residual stress and suffer more heat damage.

Abstract: This study investigates the transverse section property of unilateralism carbon fiber reinforced resin matrix composites in shot-beam shear conditions. Carbon fiber composites made in China and a composite T300 made in Japan were tested. Analysis was made for these composites on the shear strength data and the appearance of macro characters. Possible sequence of failure initiation and propagation of each composite was proposed by the SEM with optical microscopy observations of failed specimens. The result revealed that the interfacial property is the most important factor responsible for the failure mode of unilateralism carbon fiber composites, and the Chinese carbon fiber composites need to improve the interfacial property for wider use.

Abstract: In the absence of sphere templates, hollow sodailte/NiO composite spheres were obtained by one-pot hydrothermal synthesis by using polyacrylamide hydrogels as "soft template". And the effect of nickel oxide content on the synthesis of hollow complex spheres was studied. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX). The results showed that when the content of nickel oxide was about 0.5%, the hollow sodalite/NiO composite spheres with high crystallinity, stable crystal, and obvious hollow structure could be successfully synthesized.

Abstract: Aiming at the discrimination problem of the multi-point pitting corrosion fault for the vibrating machine rolling bearing, the vibration model of the multi-point pitting corrosion fault was built for the vibrating machine rolling bearing with inner ring and outer ring based on Hertz contact theory and the discrimination criterion of the multi-point pitting corrosion fault was proposed. At the same time, the theoretical model was simulated and the experiment was finished in the vibrating sieve. The experiment results are consistent with the theoretical analysis results. The results show that there is the obvious difference from the fault characteristic spectrum of the rolling bearing multi-point pitting corrosion for the vibrating machine and the rotating machinery. There is an obvious amplitude modulation phenomenon for the outer ring pitting corrosion fault of the vibrating machine rolling bearing, but there is not the amplitude modulation phenomenon for the outer ring pitting corrosion fault of the ideal rotating machinery rolling bearing. There is a slight amplitude modulation phenomenon for the inner ring pitting corrosion fault of the vibrating machine rolling bearing and but there is the obvious amplitude modulation phenomenon for the inner ring pitting corrosion fault of the ideal rotating machinery rolling bearing.

Abstract: The Mg2Ni-type alloys with a nanocrystalline and amorphous structure have been confirmed possessing superior electrochemical hydrogen storage kinetics. The melt-spinning technique is used to preparing the nanocrystalline and amorphous Mg2Ni-type alloys with the nominal compositions of Mg20Ni10-xMnx (x = 0, 1, 2, 3, 4). The impacts of the melt spinning and the replacement of Ni by Mn on the structures and the electrochemical performances of the alloys are investigated systematically. The analysis of the structures by XRD and HRTEM reveals that the replacement of Ni by Mn facilitates the glass formation in the Mg2Ni-type alloy, and the amorphization degree of the as-spun alloys increases with the growing of the spinning rate. Furthermore, the replacement renders the formation of secondary phases MnNi and Mg instead of altering the Mg2Ni major phase in the alloys. The measurement of the electrochemical characteristics by an automatic galvanostatic system indicates that the discharge capacity and cycle stability of the alloys dramatically grow with the rising of the spinning rate and the amount of Mn replacement, with which the high rate discharge ability (HRD) of the alloys first augments and then falls.

Abstract: PAN-based carbon fiber was used to prepare brush anode, and its electrochemical performance was investigated in a tubular microbial fuel cells. Experimental results showed that electricity production can be enhanced by using brush anode, with maximum current (up to 25 mA) much higher than that of reported microbial fuel cells using other types of carbon materials. Heat treatment is demonstrated to be an effective method to further increase the performance of the brush anode, not only reducing the start-up time of the microbial fuel cells, but also increasing the duration of electricity production and polarization properties.

Abstract: The effect of surface treatment using polymer surface treating agent on the morphology of the Si3N4 nanowires was studied. The morphology, microstructure and surface chemical groups was characterized by using SEM, Granulometery, X-ray diffraction, Thermogravimetric analysis, diffuse reflectance infrared Fourier transform spectroscopy, The result s indicate that surface modify can not change the morphology of the nanowires. At the same time modifier on Si3N4 nanowire surface is chemical adsorption coating. Modifier coating occurred oxidative decomposition in 200-400oC

Abstract: The thermal conductive silicon rubber have been prepared by using aluminum nitride as filler. The morphology and dispersion propriety of the filler were investigated by Scanning electron microscopy. The thermal conductivity of the composites was analysized by thermal measurement system. The results show that The larger particles give rise to a higher thermal conductivity of composites, at the same time the thermal conductivity of the composites increase with increase of aluminum nitride filler fraction. When the particle size is 60 nm, the thermal conductivity of composites at 40% volume fraction is about 3.5times that of pure silicon rubber matrix.

Abstract: carbon nanotubes were synthesized by pyroysis method using copper nanoparticles as catalyst. The structure, phase composition and hydrogen storage capacity were investigated by TEM, XRD spectra and Electrochemical System. The results show that the diameter of carbon nanotubes is 200-500nm, The P-C-T curve of adsorbing hydrogen of samples was measured in the pressure up to 12 MPa at room temperature. we show that a SWNT can strongly adsorb up to 8-wt% hydrogen. These results advance our fundamental understanding of dissociative adsorption of hydrogen in nanostructures and suggest new routes to better storage and catalyst materials.

Abstract: MP2/aug-cc-pvtz level was used to optimize geometries of the complexes between GeH4 and Y(Y=He, Ne, Ar and Kr). The structures and electronic properties of the blue-shift hydrogen bonds complexes GeH4…Y(Y=Ar, Kr) were investigated. The calculated interaction energies with basis set super-position error (BSSE) correction revealed that the relative stabilities of the complexes in the order: GeH4…He ˂ GeH4…Ne ˂ GeH4…Ar ≈ GeH4…Kr. The calculated results showed that the interactions between GeH4 and Y（Y=He, Ne）belong to van der Waals force, and those between GeH4 and Y（Y=Ar, Kr）belong to weak hydrogen bond. NBO (natural bond orbital theory) and electron behavior analysis showed that GeH4…Y(Y= Ar, Kr) hydrogen bond is with a non-electrostatic property.