Mechanical Engineering and Instrumentation

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Authors: Wei Wei Liu, Dong Fang Wang, Feng Li, Hao Chen, Cheng Zhou Wang, Jun Xue Ren
Abstract: In order to control surface residual stress in milling aviation stainless steel, orthogonal experiments were conducted to investigate the effects of milling parameters on surface residual stress in milling of 1Cr11Ni2W2MoV. The empirical formula of surface residual stress was established to analyze the sensitivity of surface residual stress on milling parameters. The milling parameters stability region and instability region were acquired. Using the extreme difference analysis method, the optimum selection of the milling parameters interval was proceeded. The results show that residual stress along X direction is most sensitive to the feed per tooth, residual stress along Y direction is most sensitive to the milling speed. The optimum milling speed ranges from 25m/min to 40m/min, the optimum milling depth ranges from 0.4mm to 0.45mm, and the optimum feed per tooth ranges from 0.06 mm/z to 0.08mm/z, surface residual stress can be effectively controlled.
Authors: E. Paese, Pedro A.R. Rosa, Martin Geier, Roberto P. Homrich, R. Rossi
Abstract: Electromagnetic forming (EMF) is a high-speed forming process that uses energy density of a pulsed magnetic field to deform metallic workpieces. This paper presents a method to calculate the electromagnetic force in thin flat plates using a flat spiral coil as an actuator. The method is based on the Biot-Savart law, and the solution of magnetic induction integral equations is performed inside Matlab® by a numerical method based on discretizing the EMF system in a system of ordinary differential equations that couple the electric and magnetic phenomena. Free bulging experiments and a comparison with Ansoft Maxwell® software are presented demonstrating a good correlation with the proposed implementation.
Authors: John L. West, Da Wei Lee
Abstract: Vacuum deposited indium tin oxide, ITO, is the material of choice for producing the transparent conducting electrodes used in a wide variety of electro-optic applications, including flat panel displays and solar cells. In addition to rigid substrates such as glass, ITO can be coated on flexible substrates for the production of flexible devices. Because the ITO is brittle it easily cracks if the flexible substrates are bent. The cracking of the ITO is therefore viewed within the industry as a major problem. Here we demonstrate how we can control the cracking of the ITO to produce uniform electrodes. This is accomplished by bending the film around a tight radius of curvature. The electrodes are narrow having a width of 5~10 μm. The cracks separating the electrodes are much narrower with a width of less than 0.05 μm. We demonstrate the use of these substrates using a polymer dispersed liquid crystal switchable window that can be switched in individual lines creating an electronic venetian blind effect. The addressed lines in the PDLC are defined by the contact electrode and by the applied field. Because the cracks are much smaller than the thickness of the active PDLC material they are not visible. In addition to switchable windows these substrates can be used to make passive matrix displays and touch screens. Uni-axially cracking can be easily integrated into a roll-to-roll manufacturing process.
Authors: Dieter Herlach
Abstract: An undercooled melt possesses an enhanced free enthalpy that enables to crystallize metastable solids in competition with their stable counterparts. Crystal nucleation selects the crystallographic phase whereas the growth dynamics controls microstructure evolution. We apply containerless processing such as electromagnetic and electrostatic levitation to containerlesss undercool and solidify metallic melts. Heterogeneous nucleation on container-walls is completely avoided leading to large undercooling with the extra benefit that the freely suspended drop is direct accessible for in situ observation of crystallization far away from equilibrium. Results of investigations of maximum undercoolability on pure zirconium are presented showing the limit of maximum undercoolability set by the onset of homogeneous nucleation. Rapid dendrite growth is measured as a function of undercooling by a high-speed camera and analysed within extended theories of non-equilibrium solidification. In such both supersaturated solid solutions and disordered superlattice structure of intermetallics are formed at high growth velocities. A sharp interface theory of dendrite growth is capable to describe the non-equilibrium solidification phenomena during rapid crystallization of deeply undercooled melts.
Authors: Chang Feng Yao, Ting Wang, Wei Xiao
Abstract: In order to optimize grinding parameters and control surface roughness in precision machining, the grinding experiment of Ultra-high strength steel Aermet100 was conducted based on three levels and three factors. The influence of grinding parameters on surface roughness was investigated, and corresponding 3D surface topography was observed. Experimental results indicate that for CBN wheel, the surface roughness decreases with the increase of workpiece speed and wheel speed; it increases strongly when grinding depth increasing; and the wheel speed has little influence on surface roughness. The optimum surface roughness can be achieved when adopting vs=24 m/s, vw=13 m/min, ap=0.01 mm within experimental parameters, the surface roughness value is less than 0.40 μm.
Authors: Xiang Jun Gong, Feng Jia, Rong Liu, Fei Ye, Hao Guan, Rui Wang, Gang Guo
Abstract: Using the Ti-bearing blast furnace slag as raw materials, hydrochloric acid as treatment agents to prepare slag containing titanium catalysts. Slag containing titanium catalyst are characterized by XRD, SEM, FT-IR, UV-Vis/NIR and some other testing methods, and the results show that its main structure is mineral perovskite phase and it also has a strong absorption capacity in the UV region. With methyl orange solution as the target degradation, influence of the calcination temperature, catalyst dosage, initial concentration and pH of the solution on the photocatalytic effect of containing titanium slag catalyst are tested. The results show that when the heat treatment temperature is 400°C, catalyst dosage is 10mg and initial concentration is 10mg·L-1; when pH is 3, the photocatalytic effect is the best, the efficiency of which reaches 95%.
Authors: Xiao Pin Wang, Yi Hui Li, Cou Hua Zhu
Abstract: This paper studied the changes in the surface morphology and microcrystalline structure of GAC modified using the original activated carbon, HNO3, FeCl2·4H20, KMnO4. The micro pore structure on the surface is damaged after being treated by HNO3, and the transition pores increase; after being treated by FeCl2·4H20 and KMnO4, the carbon surface is irregular, and there is a protuberance, which is due to the irregular loading of manganese ions on the activated carbon surface. Then the roughness of the activated carbon increases and the size of graphite crystallite of GAC is also greatly reduced, showing obvious trend of fine grains. Meanwhile, the studies of the effect of removing the trichlorophenol from water after modification indicate that the results basically match. On this basis, the modified model is put forward.
Authors: Li Xiong Zhang, Rong Gang Gao
Abstract: Based on the traditional theory of transient plane source for thermal conductivity measurement, this paper designed and developed a new pattern of heating and temperature sensing probe, presented the study of transient heat conduction of half-infinite plane while being heated, established a modified mathematical model of transient plane source method, and achieved the measurement of thermal conductivity of automotive interior material sample by the data processing method of mathematical iteration and liner regression using the modified transient plane source probe. According to the data of experiments, the instrument which this paper designed has a high precision of 5% and a wide range of 0.003-1W/(mK).This paper provides a practicable way for heat capacity determination of automotive interior materials.
Authors: Yi Hui Li, Xiao Pin Wang, Qiao Yan Jia, Chao Yang Zhou
Abstract: The carbon fiber has been widely applied in the building reinforcement because of its light weight, high strength, good viscosity, heat resistance, corrosion resistance, anti-fatigue, easy to be cutting and constructed, etc. Considering the FRP strengthened experimental data of large and full-scale concrete beam is relatively insufficient, in this paper, two strengthening methods, namely, near-surface-mounted and externally-bonded carbon fiber plate, are used for of contrastive experimental study of eight full-scale concrete beams, to analyze the influence of two strengthening methods on bearing capacity, deformation and failure mode of concrete beam, etc.The analysis results show that two strengthening methods can improve the mechanical behavior of concrete beam, its yield load and ultimate load, and delay the crack development.The externally-bonded strengthening method, however, has a high request for bonding technique, otherwise, the debonding and failure easily occur; while the near-surface-mounted strengthening method can effectively avoid the failure, and give full play to the high strength of carbon fiber plate, so this kind of strengthening method should be generalized and wildly applied.

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