Applied Mechanics and Materials Vol. 472

Abstract: Flange is the key part of the large vacuum container and its stiffness property affects the sealing effect and the stability of the container. Large flange welding process will have a greater impact on its structural strength. In view of the traditional way of forming large vacuum container flange has problems that processing and manufacturing are difficult, more material consumption, and poor stiffness, a new type of flange structure was support. The new design has hollow structure and the welding process of cover flange was simulated through the finite element method. After that, the stress and the deformation were analyzed and then the proper welding scheme was optimized.

Abstract: In this paper, a new analytical model based on a mechanistic force prediction and elastoplastic relaxation procedure predicting the deflections induced by the residual stresses in a milled micro part is proposed. The force model defines the Hertzian type distribution applied by the tool on the part. The proposed deflection model is valid for thin rectangular parts typically produced only using a micro-milling process. The deflection and the force model were analytically developed and experimentally tested on thin Al 7050 micro plates. The force model was validated using micro dynamometer and the deflection profile was verified using the white light interferometer. The proposed model showed that it has a reasonable ability to predict the residual stress induced deflection in the context of stress gradient and intensity.

Abstract: In the present study, a tungsten rod with diameter of 100μm is used as the tool to drill a quartz plate by Electrochemical Discharge Machining (ECDM). KOH solution mixed with different concentration of Ethanol is used as the electrolyte. The influences of different working parameters, such as electrolyte concentration, applied voltage, pulse frequency, and electrolyte level, on the gas film stability, gas film thickness, and machining accuracy are investigated. The experimental results show that the overcut and surface roughness is improved by the use of electrolyte with addition of 6.5wt% ethanol. The effect of gaseous bubbles is reduced during the machining, and the circulation of electrolyte is better. Compared with machining with pure KOH electrolyte, the overcut is reduced around 57% by the use of electrolyte with addition of 6.5wt% ethanol. The heat-effected zone on the machining is also largely reduced.

Abstract: Polyester fibre is the synthetic fiber made with man-made fibers. Its surface is smooth with the texture of fine linen. It has good flexibility and durability and is the best non-iron fibres. In order to promote the accuracy and reduce the quality deviation of melt spinning, the Taguchi method was adopted in the melt spinning process. The aim of the research is to enhance the optimization of the melt spinning process using the material polyester. First, the Taguchi method is applied to establish the design of experiment. An analysis of variance will be done to arrive at the significant factors that influence the melt spinning quality the most. Lastly, confirmation experiments verified the reproducibility of this experiment. Confirmed by the experiments, results showed that the obtained SN ratios were greater than the signal-to-noise ratio of nine orthogonal array experiments and this means the experiment is reliable.

Abstract: Based on the theories of induction heating and thermal conductivity, and by establishing a three-dimensional finite element analysis model including the induction coil, crank cheek and air, the pattern of temperatures field distribution and thermal deformation condition of the crank cheek during the period of induction heating were numerically simulated with software ANSYS. The simulation result showed that, by setting a circular coil inside the crank cheek, a uniform temperatures field around the hole would be obtained after a certain period of induction heating. As a result, the crankshaft would reach a high quality shrinkage fitting, manifesting the feasibility of the application of induction heating to the crankshaft shrinkage fitting.

Abstract: Conventionally, the investment casting components were separated from the casting pattern tree via a grinding machine to cut off ingate/inlet of the gating system. This post-treatment process may considerably increase labor and material costs. In this paper, a fatigue damage technology was proposed to separate the components in substitution for the cutting operation of traditional grinding machines. Mold flow analyses were conducted in the design of the gating system to ensure the casting quality. An actual vibration experiment of the casting pattern tree was conducted, and the results verified that the substitutive scheme is feasible.

Abstract: Ready-mixed concrete has gained more and more popularity in the construction projects in China. Long distance or high dislocation pump of concrete mixture is difficult to control the concrete quality , even more worse, the concrete may become drier or stocked during the pumping. How to improve the concretes pump ability is a major concern of the construction company. With the development of civil engineering, the building get much more higher and the bridge get much more longer, the pump ability of concrete matters the final product quality of the structure. This article proposed a comprehensive research on pump-ability of concrete mixture from the in field experiences by CCEED (China Construction Eighth Engineering Division).

Abstract: Five kinds of terbium complexes have been synthesized respectively with benzoic acid, 1,10-phenanthroline and 2,2'-bipyridine as ligands. The core-shell Ag@SiO₂ nanocomposites was prepared. The result of transmission electron microscopy (TEM) shows the diameter of the nanosilver is about 50 nm and the thickness of the silica shell is 10, 25 and 80 nm. Combine the nanoparticles composite with terbium complexes, we explore the changes of excitation wavelength and emission intensity. The results show that: by loading the terbium complexes above the different size of nanoparticles, the excitation wavelengths of complexes do not shift, and the emission intensity of the complexes are enhanced in the presence of Ag@SiO₂ nanoparticles because of metal-enhanced fluorescence (MEF), but at only a limited shell thickness particle region.

Abstract: We have investigated the effect of well growth rate on threshold current and slope efficiency of GaN-based laser diodes (LDs). The lasing performance was significantly dependent on optical and crystal quality of In_0.08Ga_0.92N/ GaN QWs with different well growth rates. The InGaN QWs grown with lower growth rate represented better interface quality and had low surface defects in the InGaN/GaN QW region. In addition, InGaN QWs grown with lower growth rate exhibited the higher optical properties such as the higher PL intensity and the smaller blueshift with increasing excitation power density. The present results suggest that optical and crystal qualities of InGaN/InGaN MQW are significantly improved by lowering well growth rate, resulting in the increase of slope efficiency and the decrease of threshold current density in GaN-based LDs.

Abstract: 2-D SnO₂ nanosheets with controllable thickness have been synthesized via a simple hydrothermal method. Characterization shows that the sheet thickness can be controlled from 3 to 30 nm. The correlation between the sheet thickness and the electrochemical performance of these samples as anode materials for Li ion batteries were investigated, it was found that when the sheet thickness less than 10 nm, electrodes with high charge/discharge capacities, coulombic efficiencies and stable cycling performance could be realized. The good electrochemical performance are ascribe to the ultra thin nanosheet, good flexility and porous structure of the SnO₂ anode material.