Advanced Materials Research Vols. 291-294

Abstract: Aiming at problems of planar optical waveguide aligning and coupling multi-dimensional space sub-micron motion error, with using topology theory, estimating distribution of motion error paramount precisely, this paper establishes position model of precise motion platform, based on Monte Carlo method, obtains precise position distribution of fiber end point. The result indicated that this method can obtain accurate position in the adjust process of planar optical waveguide automatic aligning and coupling, and achieve effective control of aligning and coupling accuracy.

Abstract: In this paper, both the numerical simulation and the experimental test are carried out to analyze the relationship between the direction and closure efficiency of voids during the forging process. The closing behaviors of through holes which are parallel and perpendicular to the pressure direction respectively are studied in comparison. Furthermore, the stress status and crash degree of internal voids with different axial ratio are examined to analysis the relationship between the closure efficiency and the axis direction. Finally, a method to determine the closure of voids by using stress curves is proposed.

Abstract: Centrifugal Compressors, which offer good flow stability, compact size and high stage pressure ratio, have been widely used in helicopter engines and sometime served as high pressure stage in small turbojet engines. In this paper, a method of developing a CFD model is presented for investigating the flow performance of a subsonic centrifugal compressor. The configuration used for the study is a subsonic centrifugal compressor which has a 60mm diameter impeller. A CFD modeling is carried out to obtain the performance and operational range of the compressor stage. The mesh independence studies were performed to provide confidence in the numerical results at operation speed. Particular emphasis is laid on the flow performance analysis with designed rotational speed of impeller.

Abstract: A water modeling approach was employed to investigate the effects of gas injection condition on the fluid flow in a two-strand tundish. The rational parameter of argon injection was determined as the optimized positions. Adopting the Case of weir-gas-dam could prolongs fluid’s retention, stagnation and peak periods in the tundish properly. The dead zone could be reduced to 17.4%. The flow pattern which was oberved with ink showed that the flow condition was improved greatly in Case 2(WGD), favoring the mixture of liquid steel and the inclusion removal.

Abstract: The features and functions of Autoform software for sheet metal forming simulation were introduced. Taking the auto panel as an example, based on UG and Autoform, the process of CAE simulation analysis on the drawing process was stated in this paper and the simulation results were analyzed. The results of analyses indicated that the crack tendency was in the two salient of auto panel flange in the drawing process. By optimizing and adjusting the parameters of mold, the problem of crack tendency was solved. The optimal stamping process was finally determined based on the results of the simulation. Compared with the traditional stamping technology and die designing, the quality of die designing was improved by adopting CAE technique.

Abstract: The embedded thermocouples have been analyzed with the consideration of their temperature effectiveness and the life of mould plates. Three dimensional FEM models have been adopted to study the effect of different installation of the thermocouples. The thermocouples installation methods, whatever from the back side of the plates or from the top or bottom, have been observed with little effect on the temperature field of the copper plates. But the effective Mises stress and strain are influenced obviously. The maximum stresses have been observed in the area of thermocouples channel with holes from back side of the plates. From this point of view, the holes from top or bottom of the plates are more reasonable.

Abstract: The deformation of sheet metal in the continuous flexible forming (CFF) process is complex and the formed result is affected by many factors. In this paper, the finite element model of CFF was founded and the forming processes of spherical parts were simulated with the software ABAQUS. The interaction between transversal deformation and longitudinal deformation in the CFF process is analyzed. Based on results of numerical simulation and forming tests, the process parameters of CFF is revised, and formed surface is measured by three dimensional sensing system, the measured results indicate the precision of formed parts are satisfactory.

Abstract: An improved optimization method on the material mixture ratio of ship stern bearing is proposed. During the optimized experiment of ship stern bearing material mixture ratio, uniform design and partial least-squares regression are used to extract the regression function between the optimization object factors (including friction coefficient of the stern bearings, abrasion loss in unit time)which can evaluate the performance of ship stern bearing material mixture ratio and the other experimental factors(including the material mixture ratios of stern bearing components, stern bearing processing temperature).The total optimization object function is composed by the proper weighting to these obtained regression functions.The optimized material mixture ratio will be attained when the comprehensive evaluation index which is the value of the total optimization object function gets its optimum value. Through an analytical comparison with existing optimization method , the improved optimization method can greatly reduce testing times and the experimental cost, shorten the experiment period in the allowed precision range. Based on the experimental analysis of a technology simulation model of related ship stern bearing, it shows that the improved optimization method is practicable and effective.

Abstract: In the mass concrete structure construction, the thermal insulation material and cooling pipe are important temperature control materials to prevent concrete from cracking. In order to select the right materials, their heat exchange coefficients should be obtained exactly. But no proper apparatus can give the parameters through simple measure. An experiment concrete block with the dimension of 50m long and 22m wide was established near a dam construction site and the corresponding inversion calculating was applied. The experiment method is presented. The measured curves and calculated curves meet well which shows the inversed parameters reliable. Then the heat exchange coefficients of the EPE insulation materials with different thickness and the HDPE pipes with different diameters are given. The application effect shows the selected materials have achieved the goal of crack prevention. The experiment and inversion method will provide reference to other cases and the heat exchange coefficients can be used in similar structures.

Abstract: Multi-Roll Stretch forming process is a new flexible process which is used for forming hyperbolic-degree surface pieces. Using the Multi-point flexible floating clamping system, the metal sheet can be more easily formed, and the flexibility can be much higher, which the ordinary floating clamping cannot have. A series of finite element simulations and experiments have been done for the process of forming saddle-shaped parts using Multi-Point flexible floating clamping system, and ordinary floating clamping system. The results show that the quality of the part formed using flexible floating clamping system is better.