Advanced Materials Research Vol. 426

Abstract: Monotonically decreasing sequence data for the traditional modeling method using the gray model accuracy is not high , and GM (1, 1) modeling method has inherent deviation , Model does not meet the compatibility condition, using Accumulated Generating Operation in reciprocal number ,make best use of last information and GM (1, 1) modeling , is deduced and the parameters optimization grey derivative calculation formula ,and then established GRM(1,1) based on accumulated generating operation in reciprocal number on the equidistance, Gray provides a new method of modeling . Data processing examples show that the model's practicality and reliability.

Abstract: The diamond coatings were prepared by hot filament chemical vapor deposition(HFCVD) on the mono-crystalline silicon substrates. The influence of the technical parameters such as methane volume ratio, substrate temperature and reaction pressure on the residual stress in the diamond coating was studied. The results showed that the residual stress in the coating was compressive stress in the range of parameters studied, and too high or too low substrate temperature, chamber pressure and methane volume ratio would all increase the residual compressive stress. This relationship can be explained by the influence of amorphous carbon content, vacancy density and grain size on the residual stress.

Abstract: Axial turning-grinding is a processing method to cut cylindrical workpiece or inner surface of hole along its axis, using the kinetic energy of high-speed rotation annularity tool, the abrasives in tool tip as the main cutting edge to remove materials and the abrasives in the outside surface of tool as a minor cutting edge to sharpen the processed surface. And the cutting thickness and feed rate could be more than 5~10mm and 200mm/min respectively in a cutting, realizing high-efficiency, low-cost processing of engineering ceramics. Using the method, the ceramic sleeve of delivery valve precision coupling components in the engine is processed with high efficiency, and tool wear was researched with single factor test. The result indicated that the ratio of spindle speed and workpiece speed should be within a certain range in order to minimize tool wear, and tool wear increases with the increase of cutting depth, but not a linear relation.

Abstract: A tilted head-cutter is considered the generating tool for the generation of the proposed face-gear and a mathematical model of face-gear with curvilinear shaped teeth is developed according to the differential geometry and meshing theory. The generation of a conjugated pinion is based on application of a tilted head-cutter as well. Computer graphs of the gear with curvilinear shaped teeth are presented based on the developed gear’s mathematical model, and then the equation of the gear-tooth surface is deduced. An example is presented to demonstrate the application of the proposed mathematical model.

Abstract: The effect of thixo-forging process on morphologies of particles that affect fracture mode of 7A04 alloy was studied. Microstructure and fracture surfaces of thixo-forged samples were investigated by image analyzing technique and scanning electron microscopy. The analyses of the ruptured surface were conducted with specimens taken in-situ from ruptured surfaces of thixo-forged parts. It is suggested that samples fractured in an area with higher liquid fraction have superior mechanical properties, especially elongation, and consequently a failure type of inter-crystalline cracking could be the main fracture mechanism. On the contrary, samples fractured in an area with lower liquid fraction have inferior mechanical properties and the principal resistance force is created by the contacting solid particles, a failure type of trans-crystalline rupture could be the main fracture mechanism.

Abstract: The microstructure and stress variation of semisolid 7A04 alloy have been studied through unconstrictive isothermal compressing test. The results show that the relationships between true stress and true strain at different deformation temperatures and strain rates are the same, and the peak stress in the curve of true stress and true strain mainly depends on deformation temperature and strain rate. Analysis on the microstructure of compressive specimen demonstrates that segregation of liquid-solid phase is mainly affected by strain rate and deformation temperature. There are mainly two kinds of flow in liquid phase: either from the region with relatively large hydrostatic compressive stress to the region with relatively small hydrostatic compressive stress or from the grain boundaries perpendicular to the compressive axis to the grain boundaries with a certain directional angle to the compressive direction. Based on the above results, the microstructure and stress variation mainly depend on deformation temperature, strain rate and stress state.

Abstract: The mechanical properties’ modeling of coniferous growth ring based on finite element method is present in this paper. With the basic unit boundary conditions of stress and displacement, the constitutive relation is established between macro and micro-volume field. The multi-layer model of growth ring is 3 layers, such as early wood, transition wood and latewood layer. The first order displacement field equation is substituted into the micro-variable differential to build the balance equation which has the periodic characteristics. Single-cell finite element model is calculated out using APDL language programming, and the visual results are obtained directly by the ANSYS program output window. With the FEM model, imposing the load on it, the simulation result show that it can calculate out the mechanical properties of material. Modeling Growth Ring Mechanical Properties of Coniferous Wood based on FEM

Abstract: Pipeline elbows are extensively applied in the liquid-conveying piping system, which vibration and noise control are always difficult and critical. The structural style of the guide plates for the liquid-conveying pipe noise eliminating elbow is numerical calculated in this paper, then we find that the fluid liquidity in the liquid-conveying pipe elbow is improved very well by the cross-sectional bending radian and export length of the guide plates, and the two parameters are also optimal designed. The calculated results show that the total pressure difference in the liquid-conveying pipeline elbow decreases first and then increases with the cross-sectional bending radius of the guide plate increases; The total pressure difference decreases first and then increases with the export length of the guide plate increases; When the guide plates according to the gold ratio arrangement, the number, the cross-sectional bending radius and the length are 2, 200 mm and 40 mm respectively, we obtain the total pressure difference is 10707.87 Pa in the liquid-conveying pipeline elbow, comparing it to the result of the original program, it decreases 38.58%, so the internal flow field is improved better, the optimal design has a very obvious effect.

Abstract: Nickel-based alloy Inconel718 is a difficult-to-cut material due to lower thermal conductivity, affinity to react with tool material, the cutting tools wear very rapidly due to the high cutting temperature and high cutting force. It is important to choose tool material reasonably. In this paper, cutting performance of the multi-layer CVD-coated (TiN/Al2O3/TiC) tool and PVD-coated (TiAlN) tool were evaluated by cutting temperature, cutting force, tool wear and tool life. The results showed that PVD-coated (TiAlN) tool was suitable for cutting Inconel718.

Abstract: Based on the experiment of high speed ball-end milling hardened steel, investigated the distribution characteristics of cutting force and cutting heat and wearing character of cutter, and set up analysis model of cutter physical field. Using failure criterion and safety margin of cutter, founded physical field evaluation model of high speed ball-end milling cutter. By means of physical field analysis and experiment, explored the influence of cutting parameters on cutting property during cutter wear. Results indicate that the method of safety margin and physical field evaluation model can evaluate cutting property of cutter effectively, the impact of feed per tooth on physical field and safety margin is noticeable, and high speed and small feed are helpful to improve safety margin and cutting performance of cutter.