Advanced Materials Research Vols. 189-193

Abstract: A mathematical model was derived to describe knots in radiata pine logs and the boards quarter-sawn from these logs, based on the geometrical configuration and the growth features of the knots. Scenario simulations for the shape and the location of knots are presented, and the significance of studying knot architecture is discussed in the paper.

Abstract: Investigation on the turbulence model for resistance calculation for autonomous underwater vehicles (AUV) with the typical Myring shape is presented in this paper using computational fluid dynamics (CFD) method. Resistance calculations of the 3D viscous flow over an AUV model are made by solving RANS equations with different viscous models. Comparison with experiments indicates that the SST k-ω two-equation viscous model is the most appropriate model for the resistance prediction.

Abstract: The mathematic model of 3D aluminum extrusion processes using finite volume method (FVM) was established in this paper. The basic theories and rigid-plastic flow theories of this model were researched and built. Non-orthogonal structured grids were used to match complex geometric boundaries and local refinement of grids was also realized. The collocated arrangement is used to discretize the governing equations on non-orthogonal grids directly, pressure oscillations bring by this arrangement and error caused by grid’s non-orthogonality is eliminated by special treatment. A pocket die extrusion process was simulated using the program developed in this paper. The simulation results were also compared with that simulated by FEM software Deform in the same process, material and die conditions. The feasibility and efficiency of the mathematic model built in this paper was demonstrated by the simulation results and the comparison.

Abstract: The effect of rare earth (RE) on microstructure and impact toughness of hot rolled low carbon structure steel based on the Compact strip production (CSP) process was investigated in this work. Scan electron microscope (SEM) were employed to characterize the microstructure and analyze the fracture surface. Moreover, hot compression experiments were also adopted on the Gleeble-1500 hot simulator as well. The results indicate that acicular ferrite and/or ultrafine ferrite morphologies can be induced when an appropriate amount of rare earth added into the low carbon steel, which possessed the satisfied strength and toughness behaviors. Compared with commercial low carbon structural steels, the additions of RE can improve dynamic recrystallization critical strain of low carbon structural steel as well. In addition, the role of RE on the formation of these acicular ferrite morphologies has been investigated.

Abstract: This work employs FDS to simulate the heating process of a tunnel-type dryer and visualizes the computational results using Smokeview. The inappropriate design of a tunnel-type dryer in a factory has motivated this work. This poorly designed dryer not only has caused terrible fuel consumption but also produced parts some of which are under- or over-cooked. These are caused by the terribly uneven temperature distribution within the dryer. In order to improve the evenness of temperature distribution, this work simulates and investigates the effects of various ventilation schemes. Based on the results, it is found that the hot air intake vent should be placed at the bottom whereas the cold air outtake vent at the top. The flow rate through the intake vents does not have a very significant effect on the temperature distribution after 40 s.

Abstract: In this paper, the research topic is that the expert experience is established by the size of the measured signal strength of wireless sensor networks and put the strength of the actual collection of historical data into the neural network model. In order to get the minimize error we use the errors to modify the weights and threshold of the neural network links. We compare the differences of hidden layer neural network and the experimental results. We set up a wireless sensor networks environment to collect the measurement values of signal strength (RSSI) and develop an indoor positioning system.

Abstract: Undeformed chip thickness is one of the most important parameters in grinding process, which is related to the entire abrasive grains in grinding simultaneously and changed periodically with time. Simplifying the geometric shape of abrasive grains ,the paper modifies the mathematic models of undeformed chip thickness by analytic method, establishes an universal calculation model of grinding force based on undeformed chip thickness, then optimizes the parameters of the model by restrictive random direction method according to the measuring experiments of the inter-grain spacing about CBN electroplated wheels and the grinding experiments of steel 55 during surface grinding, analyses the influence factors of the friction ratio on the grinding force. The results show that under the same grinding depth， both of the ratio and the grinding force will be decreased with the increase of velocity ratio VS/VW, but the ratio increases and the grinding force decreases with the increase of inter-grain spacing.

Abstract: A novel limited slip differential mechanism for wheeled vehicle is introduced in this paper. A new modeling method for spatial cam mechanism used in the differential is detailed derived. The melding method and the formulas of induced normal curvature for conjugate surfaces of the cam mechanisms is derived on basis of meshing theory of conjugated surfaces and differential geometry theory, and the results provide theoretical foundation for the cam optimization.

Abstract: By using Deform-3D software, the necking extrusion forming processes of integer trailer axle with two different heating means which are Uniform Heating (UH) method and Partly Heating (PH) method with temperature gradient are simulated. The influence of deformation parameters such as friction factor, necking coefficient, different temperature distribution of work-piece on the material flow features, stress and strain field, loading force and deformation process are analyzed in detail. According to the numerical simulation results, using PH method with temperature gradient can improve necking deformation during tube extrusion process.

Abstract: Annular flow is a based flow pattern of two-phase in the pipe, and oil air flow in delivery pipe of Oil-Air lubrication (OAL) system is one of them. In order to learn the entrainment mechanism of annular flow in OAL pipe, both experiment adopted observational method and numerical simulation used Computational Fluid Dynamic (CFD) were carried out. The pipe diameter is 4mm and Volume of Fluid (VOF) model was used for two phase flow in simulation. The results shows that: it is a wave-annular flow in OAL pipe, and the oil wave in pipe is affected by air, when air velocity is low, the wave is clearly and regularly, but when air velocity increases, the wave become turbulent. When oil or air flow rate increases, the shear stress of pipe wall will be increased, the wave height will be increased as air velocity increases.