Advanced Materials Research Vols. 199-200

Abstract: The machinery composition and working principle of 3-TPT parallel machine tool were analyzed. The three dimensional solid models of components of 3-TPT parallel machine tool were designed by using Pro/E. The virtual assembly and connection of the machine tool were accomplished in the assembly environment of Pro/E. Besides, the three-dimensional motion simulation of mechanism about the machine tool was researched in the mechanism module of Pro/E. The three-dimensional animation achieved by the simulation has the strong sense of reality. The working principle of the parallel machine tool was verified by the simulation. The simulation results show that the machine tool has advantages such as good stationarity, no interference and no singularity.

Abstract: Over the past three decades, three-point support/ suspension converter with brackets would cause abnormal sound and vibration while it tilted over certain angle, and engendered abrasion of bracket contact surfaces, this phenomenon increases mechanical maintenance cost and confuses lots of engineers. Through FEM analysis, three-point suspension converter’s over-constrained mechanical system and elastic friction vibration principle could be revealed, and then the solution proposal was raised. In the engineering practice, the solution proposal has been verified, and some conclusions of those theories have already been proved.

Abstract: The combustible material of fire in fog discharge pipe is the cooking oil tar. Cooking oil tar was conducted on a specially designed laboratory-scale thermobalance (Macro-TG) with sample loading of 15g under dynamic air atmosphere. The effects of heating rate (5, 10, 15, 20 and 25°C/min) was examined. A simple kinetic description, named in this work as ‘First Order Reaction and Three-dimensional Diffusion Separate-stage Model (O1+D3)’ model, was developed based on the experimental results and integral analysis method. Experimental results shows that large amount of sample has a pyrolysis reaction retardancy. The distributed activation energy model was used to study the pyrolysis kinetics. Science the reaction occurred in small activation energy told us that if the cooking oil tar put on fire it will be spread rapidly and hard to put out.

Abstract: Mechanism of flow boiling heat transfer in micro-channel and mini-channel with non-azeotropic refrigerant mixture R32/R134a is studied in this paper. Experimental research is carried out at different mass flow rate, heat flux and quality. The difference of heat transfer in two single tubes is analyzed.

Abstract: The paper aims at the problem of heat dissipation on the surface of stator of the Synchronous Motorized Spindle system, researching the influence which the shape of the cooling pipe’s cross-section and the wall thickness have on heat transfer. This paper presents the optimization design methods to confirm the best size and shape of cooling pipe’s cross-section and the optimal wall thickness, using MATLAB software to optimize calculation and NASTRAN finite element software for simulation analysis, and the ideal temperature of distribution is got, which is better than the result gained by the experience. It provides theory basis for the design of cooling pipe in practice.

Abstract: Planetary gear mechanism has compact structure,high single-stage transmission ratio,high loading capacity and efficiency. The volume of planetary gear mechanism influenced coal loading efficiency of thin seam shearer drum.With regard to this, digital product model,digital simulation and simulation were combined to design the planetary gear mechanism of shearer cutting department. It can improve designing efficiency and reliability of planetary gear mechanism，and enhanced coal loading efficiency of shearer drum.

Abstract: Under thermal stress, the formed platelet of Liquid Rocket Engine (LRE) transpiration cooling structure may result in wrinkling. The stability of rectangular sheet with three simple supported-sides and one free-side is simplified as the model of formed platelet. Applying the Galerkin method for analysis, the relationship of the critical thickness of formed platelet and the transpiration width is obtained. Also, the influence of different material properties on the critical thickness is presented. The theory and method proposed in this paper are applicable for more complicated temperature distribution and also can be used to choose material for transpiration cooling.

Abstract: Based on finite element analysis software ANSYS, the deformation and force condition of the rubber sealing o-ring pre and post with back-up ring under different oil pressure conditions was analyzed. The von mises stress distribution of the o-ring and the change of contact pressure between o-ring and sealing interface pre and post with back-up ring under different oil pressure conditions were discussed. The results show that, the maximum von mises stress of the o-ring is smaller and the maximum von mises stress of the sealing system concentrates on the left top and the right bottom of the back-up ring after using it; the o-ring will not be extruded into the gap of the groove because of the existence of back-up ring which prevents gap-bite and prolongs service life of the o-ring; the contact pressure between o-ring and sealing interface increased, thus the sealing reliability of the system increased.

Abstract: In the infrared optical system ，due to the special infrared imaging system, the stray can have the very tremendous influence to the image formation，this article utilizes the SolidWorks 3D design software design, and use the extinction thread ZEMAX optical analysis software on the extinction of a thread, the infrared lenses for analysis, through theoretical and practical study proves that extinction thread on infrared system weakened noticeably stray light radiation, infrared imaging have a beneficial effect. On the future of weakening the stray light offers a new method.

Abstract: For finding influence of the condensing surface to dropwise condensation heat transfer, a fractal model for dropwise condensation heat transfer has been established based on the self-similarity characteristics of droplet growth at various magnifications on condensing surfaces with considering influence of contact angle to heat transfer. It has been shown based on the proposed fractal model that the area fraction of drops decreases with contact angle increase under the same sub-cooled temperature; Varying the contact angle changes the drop distribution; higher the contact angle, lower the departing droplet size and large number density of small droplets; dropwise condensation translates easily to the filmwise condensation at the small contact angle ;the heat flux increases with the sub-cooled temperature increases, and the greater of contact angle, the more heat flux increases slowly.