Applied Mechanics and Materials Vols. 321-324

Abstract: The most important process of forming simulation pretreatment is to determine drawing direction. As the main factor to effect the flow direction and velocity of sheet metal, the unreasonable drawing direction would lead to fold and wrinkle of panel . Moreover, the reasonable drawing direction is an important basis of drawing mould structure and the subsequent process design. The traditional drawing direction of panel depends on the experience of technician that constantly rotating part, which rely on the experience of technician and would consume more time and labor force, furthermore, it is difficult to stable obtain the optimal direction in the feasible region of the drawing direction.The measured results show that the direction of the drawing based on genetic algorithm, the automatic algorithm can fast and accurate to obtain the optimal direction of drawing.

Abstract: This article introduce the current research situation on the influence of the depth of the slag pool in electroslag casting, comprehensive analysis how the outer technological parameters are affected by the depth of slag pool in electroslag casting, for example: the influence on the consumable electrode end shape, the slag pool temperature field, the depth of the metal molten pool. These research results provide an important reference bases on guiding actual production of electroslag casting, optimizing process parameters, stabling casting process, improving production efficiency.

Abstract: This paper gives a way which utilizes the PTC (positive temperature coefficient) materials to preheat diesel in the injector in order to improve the cold start performance and emissions of engine. Combining high performance data acquisition system based on MSP430F149, a dynamic temperature testing system was developed to test fuel temperature heated by PTC in injector. The software and hardware electrocircuit were expounded in detail. The temperature varying law of diesel fuel heated with PTC ceramics was measured under different voltage. A conclusion can be draw that diesel fuel may be heated to self-defined temperature around Curie point when diesel fuel was heated with PTC material.

Abstract: The reaction mole ratio of monomers, pH value, reaction temperature and time factors directly affect the properties of urea-formaldehyde resin (UF)/low melting point paraffin wax microcapsules during in situ polymerization process. The effects of these factors on the thermal storage capacity, particle size and distribution were systematically discussed. When the reaction conditions were formaldehyde and urea molar ratio of 1.8:1, the prepolymerization system pH controlled at 8.5, the reaction temperature of 60 °C, the reaction time of 60 min, the synthetic phase change materials microcapsules have good morphology and thermal storage capacity.

Abstract: Sloping layer is an important level of Flat Roof. It usually have both slope and heat insulation double function. Its thickness is obtained through energy conservation. But because its thickness is variable, in engineering practice it is difficult to accurately determine the thickness. The sloping layer thickness depends on the requirements of the roof energy saving. It is important to thoroughly analyze the principle of roof heat transfer and to establish the mathematical model of roof heat transfer. Then through rigorous mathematical calculation, the common law of how to determine the sloping layer thickness can be summed up. According to the slope gradient, slope length and layer thickness calculation value, the maximum thickness and the minimum thickness can be ultimately determined.

Abstract: The uniform sub-micron colloidal spheres were arrayed on the surface of a Si substrate via self-assembly to forming a sphere-layer film (monolayer), with emphasis on the application of rolling friction in the presence of rolling spheres on the surface of micro- or nano-equipment. It was found that the arrayed spheres on the substrate are mobile arising from rolling, and they can significantly reduce the friction force through changing the sliding friction to rolling one, thus exhibiting a smaller friction coefficient value than that of pure substrate. On the other hand, the elastic deformation of polystyrene (PS) spheres also contributes to the reduced friction force. In the absence of lubricant, the optimal friction coefficient of sphere-layer film was found to be 0.059 at the load of 3500 µN, at which the friction force of sphere-layer film was only 68% that of substrate. The friction coefficient of sphere-layer film decreases with increasing the applied load up to 3500 µN, followed by an increase with a further enhanced load, which has been ascribed to the transition from elastic contact to plastic one.

Abstract: All die-casting products should be made by the production processes of product design, blank design, mold design and die-casting, etc. However, for the short delivery cycle ,many enterprises more or less tend to complete the work in sequence mentioned previously ,and don’t rely on the calculation but experience when designing. They will enter an absurd cycle as the time passes. The work done later is often used to remedy the defect which was caused by work done previously. Some problems may be solved by the later work, but some defects can not be remedied by the later work for ever, furthermore, they can’t ensure the quality, delivery date, qualified rate, productivity, and so on. So it is critical to make whole calculation scientifically in previous.

Abstract: Dual phase (DP) steel is a high strength steel for auto-panel. In this paper, mechanical property, forming ability of high strength steel DP450 are studied by experiments and compared with those of steel MS6000. And theoretical research on predicting the forming limit of steel DP450 by the NADDRG model. The established mathematic model for relativity is of practical usefulness. Experimental results reveal that the yield strength of steel DP450 is about 7.2% lower than the MS6000, and the break strength increases by 18.9%, while the elongation increases by 19%. The results show that mechanical property of high strength steel DP450 is better than that of MS6000, while forming ability of DP450 is not lower than that of MS6000.

Abstract: The riveting joint is the main connection method in aircraft assembly. There are some kind of rivets, such as slug rivet and protruding rivet, that riveting quality will be impacted while rivets axis are not coincident with the plate holes axis. By using the finite element method with ABAQUS software, this paper built the 3D riveting joint structure of finite element, and analyzed the axis deviation effect on the deformation, stress and strain of riveting. Through statistical data, the relationship among axis deviation value, deformation, stress and strain of rivet are built.

Abstract: Tourmaline is a kind of natural low-cost mineral material. It has a number of unique physical properties and has been a kind of promising environmental material in wastewater treatment. This study was to investigate the aerobic biofilm treatment of coking wastewater with and without tourmaline addition. The results indicated that tourmaline added in moving bed bioreactor (MBBR) process could enhance the removal efficiency of chemical oxygen demand (COD).The organic contaminants could be removed by tourmaline added. The mechanisms of increase of organic contaminants removal may correlate to the existence of tourmaline spontaneous electrode. Micrograph of the excess sludge in the tourmaline-MBBR system indicated that the tourmaline added could be the carrier of the microbe and also affect the biomass and pollutant removal.