Materials Science Forum Vols. 532-533

Abstract: The research of lubrication oil flow on gas/liquid two-phase flow is necessary in the designing process of engine bearing. It influences the consequent design and the whole engine’s reliability. This paper proposes the two-phase homogenous flow model considering lubrication oil and air. Based on the homogenous flow model, the Navier-Stokes equations is solved by the methods of the turbulent model and Finite Differential Method (FDM) to obtain the flow field and the influence of conditional and structural parameters on the flow. With the results, the results from single flow model and two-phase homogenous flow are compared. And the effects of air volume fraction, rotor speed and lubrication oil speed at entrance on exit pressure and speed are discussed.

Abstract: A thermal elasto-plastic asperity contact model is investigated in this paper, which takes into account the steady-state heat transfer and the asperity distortion due to thermal elasto-plastic deformations. A hard coating and a soft coating are applied to study the correlations between contact area and contact pressure, average gap and contact pressure, coating thickness and contours of the contact stress distribution et al. The effects of material properties, the coating thickness, frictional coefficient, and the heat input combinations on the stress distribution are investigated and discussed. The results may help to make an appropriate choice of the hard coating thickness.

Abstract: China aviation project has little sample and the traditional method can not estimate the project cost accurately. This paper proposes a method estimating aviation project cost based on gray systematic theory. We divide aviation product into systems or parts and regard them as cost estimation unit. The gray forecasting model GM (1, 1) was set up based on historical cost data of cost estimation unit. If the model’s precision doesn’t meet with the requirement of aviation project cost estimation, the revision model GM (1, 1) must be set up to raise the estimation precision The experimental results show the method can get the more high-accuracy estimation value using the little sample and is suitable for the cost estimation of the our country aviation project.

Abstract: The modern manufacturing industry requires the cutting process to reduce the quantity of pollutants, to ensure the product quality, to make good use of the resource and energy, and to satisfy the need of productivity and economy at the same time. The cutter reasonable selection is one important method of improving cutting capability. Therefore, it can solve efficiently the new problem in machining process to think of synthetic effect with quality, economy, resource and environment at the same time. Furthermore, because the process in metal cutting is variable and the influence of most factors can not be confirmed, the fuzzy assessment based on fuzzy integrate can select more justified cutter in cutting process.

Abstract: Analysis of the forging of gas turbine rotor blades is a complex operation because of the complicated three-dimensional geometry and the non-steady state contact between the workpiece and the die surface. As a result, the simulation of blade forging performed so far has been restricted to two-dimensional plane-strain problems or simplified three-dimensional deformational cases throughout which some simplifications and assumptions are employed. In this paper a three-dimensional analysis of the non-isothermal multi-stage forging process of a gas turbine rotor blade from a cylindrical billet to a complicated product is presented, using 3D rigid-viscoplastic FEM. The simulation results of the blade forging processes are summarized in terms of deformed configurations, the material flow net pattern of typical cross-sections, the distribution of different field variables such as strain and stress, and the load-stroke relationships for each operational stage, in this way the forming laws during forging process of a gas turbine rotor blade being revealed. The validity of simulation results has been verified through comparisons with forging tests, which show good agreements with numerical simulation results. The simulation results may be effectively applied to other types of three-dimensional turbine blade forging processes.

Abstract: Aiming at the characteristics of turbine compressor’s impellers, such as complexity in surface, assembled structure and variety in parameter, the step-by-step design thought is put forward, which realizes the high efficiency and visualization of parameterized design through distributing design parameters evenly to several phases or interfaces. According to the demand of the enterprise, SolidWorks CAD Software was chosen as the three-dimensional CAD platform, SQL Server 7.0 was chosen as the database management system, and Visual C++ was chosen for the programming language of secondary developing. Then the parameterized design system for series turbine compressor impellers is developed, which realizes automatic creation of 3D models and 2D engineering drawings using template technique.

Abstract: The interaction between a cermet cladding plate part and a homogeneous cylindrical part under wear condition is simplified as a plain strain contact problem. Based on Hertz contact theory, the theoretical model of the maximum shear stress in the cladding part is built; an example and its finite element analyses (FEA) are given. Theoretical results well coincide with those of the FEA. Both results show that, with the increase of the cladding thickness, the maximum shear stress decreases, its position shifts toward the clad surface. The effects of the wear load and the properties of the frictional materials on the maximum shear stress are also studied. The research results have great significances to the design of cladding parts under wear condition.

Abstract: Self-hardening calcium phosphate cement (CPC) could not be used to repair a large segmental defect in a load-bearing bone because of its brittleness and weak shock resistance as well as ultra-minute pores. Recent studies incorporated fibers into CPC to improve its strength. A novel approach by rapid prototyping and rapid tool technique (RP/RT) was used in this paper to fabricate fibre-reinforced CPC composite artificial bone. The subsequent mechanical experiments demonstrated that the compressive strength of the CPC-fiber artificial bone was 24MPa, which was significantly higher than 6MPa for CPC control without fiber. And in-vivo experiment about canine radius repair proved that the implanted CPC-fiber artificial bone enabled to provide short-time reinforced mechanical strength, while the degraded fibers created new macropores for new tissue ingrowth. In summary, the CPC-fiber artificial bone may facilitate bone ingrowth and its four times increase in strength may help extend the use of CPC to larger bone repairs in moderately stress-bearing locations.

Abstract: A finite element model (FEM) of high-speed cutting was built to study the mechanism of high-speed machining of alloy cast iron used widely in auto panel dies. The mechanics properties of workpiece material were obtained in the conditions of high strain-rate, high temperature and high strain through high-speed impact compress experiments. Several key technologies are studied such as friction and chip-tool heat conduction. The cutting temperature, stress distribution, and the chip formation process in the process of high-speed cutting alloy cast iron were analyzed based on the finite element model, which was validated through cutting force experiments. It shows that the FEM can simulate the high-speed cutting process of alloy cast iron materials.