Applied Mechanics and Materials Vols. 271-272

Abstract: The Mechanics property is important for Mecanum-wheel structure. According to function and capacity of wheel, the structure of omni-directional Mecanum-wheel is designed and mechanical boundary condition is analyzed on different working status. On the basis of mechanical analysis, the finite element model is established and loads are applied. Strength and fatigue failure life of every parts are calculated respectively under different working conditions. The result shows that the structure and size of Mecanum-wheel is correct and meet the demand of mechanical property.

Abstract: In order to solve the machining translocation of the nuclear water chamber sealing head, a new Two DOF Heavy Positioner structure is proposed as the auxiliary equipment of processing nuclear water chamber sealing head. The article briefly describes the components of the 2 DOF heavy positioner, analyses the motion of the Turns-over Structure with analytical method and calculates variation of the swinging position of the screw , overturning speed and acceleration with Matlab as a platform，and verifies the correctness and credibility of the results by ADAMS simulation analysis.

Abstract: Based on the modal analysis of finite element theory, in this paper, a 3-D model is built in CATIA. And simplify the details of the characteristics and constraints depengding on working condition. The Lanczons method of ANSYS software is used in the model analysis in order to obtain natural frequencies and vibration mode vectors of the former 15 orders. And the dangerous areas is located in the crankshaft. These provide a theoretical basis for the optimized design of the crankshadft.

Abstract: In order to improve efficiency of designing point-line meshing gears further, goal programming is used in point-line meshing gear optimization design. Optimization goals are the actual bending fatigue strength safety coefficient, the actual contact fatigue strength safety coefficient and composite stiffness of point-line meshing gear and the optimization mathematical model is established. A example is used to verify the method.

Abstract: The dynamic modeling of a rotor system on misaligned journal bearings is discussed and its nonlinear dynamic behaviors are considered in this paper. Firstly, a dynamic model of six degrees of freedom system is established under the conditions of the long bearings, small bearing misalignment and mass unbalance. Then, the nonlinear dynamics of the rotor-bearing system, such as the displacement response and its frequency spectrum, rotor orbit and its Poincare map are analyzed by the Runge-Kutta method. The results show that at low speed the steady-state responses of the rotor system in lateral direction is synchronous, as the speed increases a serious of bifurcation phenomena and chaotic oscillations occur. In many cases, there exist the integer multiples components of the rotating speed except the synchronous one in displacement responses.

Abstract: To the unsteady characteristic of three-dimensional flow in the gas turbine blade cascades, based on sliding mesh and a standard turbulent flow model, Fluent software was employed to solve the Reynolds averaged N-S equation. The numberical result of unsteady flow field is obtained in gas turbine cascade for supercharged marine boiler. This paper shows the axial distribution of Ma in the position of β=0 in a calculational period time, and the effect of trails to flow field characteristics. The result can provide guidelines for aerodynamic optimization design of gas turbine stage cascade.

Abstract: In this paper, both equivalent Young’s modulus and bucking load of the honeycombs are calculated using the finite element method. Honeycombs consisting of either regular hexagonal, equilateral triangular or square cells are considered. Numerical results are systematically compared with theoretical results from other literature. It is found that honeycombs display orthotropic properties. Such a fact is different from that reported in open literature. Moreover, the buckling modes are discussed, and the modified expressions of the equivalent modulus and bucking load are given.

Abstract: The numerical simulation for dynamic characteristics of the flow field of a novel twin-screw kneader is carried out. The flow field model of the twin-screw kneader is established, and the three-dimensional, isothermal and steady numerical analysis of non-Newtonian fluid is presented based on computational fluid dynamics (CFD) theory, and the characteristics under the conditions of different speeds and center distances such as the distribution of pressure and velocity field, the maximum shear stress, the mass flow rate and so on, are studied. The research results show that: with increasing speed, the maximum flow pressure, the mass flow rate, the maximum shear stress will increase; the maximum shear stress increases first and then decreases with increasing of center distance of the screw rotors, while the mass flow rate increases with increasing of center distance; but when the center distance reaches a certain degree, the mass flow rate will be negative and the material will appear serious reflux which can lead the kneader to stopping working.

Abstract: Heat dissipation and working efficiency of transport air in rolling bearing under oil-air lubrication are closely related to the flowing state of oil-air in bearing chamber. For cylindrical roller bearing NF211, numerical simulation model of oil-air flow field in bearing chamber was established combining with the practical structure features of rolling bearing and ignoring the effect caused by roller rotation. Combining with flow field numerical simulation functions of Fluent software, simulation analysis of the flow state in bearing chamber were carried out. Based on k-ε turbulent model, three-dimensional flow field in the bearing chamber and main feature parameters of inner flow were got analyzed carefully considering the effect of twirling. Comparing with the numerical simulation of simplified flow field, it showed that energy dissipation and axial velocity of the air were influenced by the effect of twirling distinctly. Simulation results were expected to give useful references for the optimization design of the oil-air lubrication system in rolling bearing.

Abstract: A basic model with both property of thermodynamic and heat transfer is obtained by simplifying the prime process of ship Steam Power System (SPS), which is converted into endoreversible Carnot Cycle by the introduction of mean temperature in the cycle process. The design parameters is analyzed and optimized in the view point of finite time thermodynamics (FTT) and entropy generation minimization. Results show that, the temperature ratio (α) and the heat transfer parameter ratio (β) of heat source and heat sink are two important influence factors of cycle system performance, and the increase of α and decrease of β will redound to the reduction of irreversible loss and enhancement of power output.