Applied Mechanics and Materials Vols. 556-562

Abstract: Carbon fiber reinforced plastics (CFRP) are highly promising materials for the applications in the aerospace industries, but they are typical difficult-to-cut material. In order to improve the quality, helical milling technology was developed. In this study, helical milling experiments were conducted in the machining center about CFRP materials. The hole quality including the surface roughness, the diameter error and the roundness error are analyzed. The result shows that the hole quality was improved corresponding to drilling technology.

Abstract: The hydraulic support is mainly used in roadway and workplace for supporting and protecting in mining industry. The hydraulic support would appear the situation of declining, dumping and crowding on greater tilt angle mining face, these will threat the safety of the workplace, the safety of mining face is the key to the safety in production. This paper analyzes the reasons of declining, dumping in static force, gives respectively the angle range of working surface hydraulic support declining and dumping, proposes some relevant measures of the hydraulic support declining and dumping.

Abstract: The state-of-the-art plane-wave methods combined with ultra-soft pseudo-potentials were employed to study the crystal and electronic structures (density of state, band structure) of aluminum in its hcp and bcc structures. In our computation we used the PBE functional, which predicts lattice constants very close to the experimental data. The calculations reveal that the whole valence band of Al is dominated by the 3s and 3p states while the conduction band is mainly contributed by the 3p band. The band structure shows that bcc-Al has a 0eV gap, which reflects its metallic character. The dispersion curves near the valence band maximum and conduction band minimum are quite flat. Generally speaking, our work is an attempt to study the high pressure electronic structures of Al, which needs to be verified by experiments.

Abstract: Since spectral curves were obtained by experiment, on the basis of the fully use of the waveform characters, a new method for spectral matching pretreatment has been proposed in this paper. Corresponding to the spectral curve, we can accurately get the spectral absorption curve of the number of bands, it can effectively suppress the effects of the noise according to the times of fitting the points. Besides, it can also prominent the peak point of the material. This method can have an effective influence on the initial period of spectral match and detailed resolution; some numerical simulations have been made to test the validity and capability of the proposed method.

Abstract: Composite insulators suspension clamp fractured of a high-voltage transmission lines in Yunnan. Through the broken suspension clamp conducted visual inspection, fracture examination, material analysis, finite element simulation to determine the cause of the accident and proposed improvements. For the electrical fittings defect detection and accident analysis provide reference.

Abstract: Electronic structure and optical properties of 2H-SiC are calculated by the first-principles calculation based on density functional theory, thus to give out the relation of electronic structure and optical properties of 2H-SiC material in theory. It is theoretically predicated that the 2H-SiC is an indirect band gap semiconductor with all valence band maximum located at Γ point in Brillouin zone and conduction band bottom located at M point of Brillouin zone. The optical property of the 2H-SiC for the band-to-band transition is analyzed by using the calculated band structure and density of state. The result of optical properties shows that obvious dielectric peaks appear in 0~10eV which absorb the band edge to correspond to the ultraviolet band. Therefore, 2H-SiC material maybe become the excellent ultraviolet semiconductor material.

Abstract: Extremely low frequency electro-magnetic field (ELFF) exposure could induce hepatoma Bel-7402 and SMMC-7721 cells lines into early apoptosis without some significant effects to healthy hepatic cells HL-7702 cells in low exposure dose through affecting cellular membrane ion metabolism. Magnetic nanoFe₃O₄ particles (MNPs) presence with low effects to all hepatic cells lines strengthened ELFF bio-effects to tumor cells inducing more amount of tumor cells into early apoptosis with low effects to HL-7702 cells. Western-blot results indicated the early apoptosis signal channel Bcl protein family of tumor cells was activated significantly more effectively than HL-7702 cells due to higher MNPs uptake ratio of tumor cells and higher cellular membrane ion exchanging current than HL-7702 cells. Patch-clamp results showed MNPs combined with ELFF treatment inducing cells into early apoptosis should be partially based on ion metabolism disturbance of cells with similar to ELFF bio-effects to cells.

Abstract: In some substations, shielded wire is made of Copper Clad Aluminum, it can be severely corroded because of the exposing in the air. To reduce the loss, an economy and effective way must be developed. Isolating the shielded wire from moisture and exposing in the air is the best way to protect it. How to replace the corroded wire which is exposing in the air, while the electric cable still working is an important problem to be solved currently. This paper introduces a replacement technology—multi-strand copper wire replacement technology, which can accomplish the replacement work of shielded wire without power outage. This will be a major breakthrough in the power industry.

Abstract: In order to reduce the energy consumption and working procedure for manufacturing thin-walled titanium alloy components, a hot stretch-creep forming (SCF) technique via resistance heating is proposed to form the hard-to-form material. Firstly, the principle of hot SCF was introduced that the technique can manufacture titanium alloy components precisely because the residual stress relaxes in the material during the dwelling time. Secondly, the hot SCF equipment via resistance heating was developed, which makes use of electrical current for heating the titanium materials to improve their ductility. Then based on a set of optimized process parameters, including forming temperature, stretch velocity, post stretch percentage and dwelling time, a comparative experment of single curvature Ti-6Al-4V alloy sheet components was conducted via this innovative technology to examine the hot SCF equipments and the effect of creep forming. Results show that the component precision of the hot SCF is more precise than that of the hot stretch forming (SF) due to the creep in the stress relaxation period. Comparing to the as-received material, the yield strength of the material suffered hot SF decreases a little; while the strength suffered hot SCF increases a little. This novel technique shows a promising future to manufacture titanium sheet or profile components precisely as a feasible and cost-effective way.

Abstract: Selective laser sintering (SLS) is an additive manufacturing technique used for the low volume production of prototype models and functional components.The lower strength of prototype parts might leads to bad finished quality. In this study, author used the coated sand casting as the material of selective laser sintering experiment, studied the processing temperature and time on the mechanical properties of post-processing, and the influence on gas-forming property and collapsibility of the pieces. And combined with casting experimental we can analyze the accuracy influence factors of precoated sand sintering parts and other performance assessment. Through analysis, it indicates that the post-processing of temperature influences on tensile strength of coated sand specimens under three different insulation temperature conditions.