Applied Mechanics and Materials Vols. 494-495

Abstract: The grinding process is currently used for machining the parts requiring for good precision. However, the apparition of some damage related to this process is still uncontrolled, in which the major deterioration is from the residual stress. Through grinding and hardening test, the residual stress distributions under different grinding speeds are obtained, and then numerical simulation for thermal stress of the workpiece surface is carried out by finite element software ANSYS to deduce the distribution of phase transformation stress under different grinding speed.

Abstract: The importance of the surface integrity in modern machining is represented. Based on the notion of the surface integrity that was put forward by Michael Field, a new method of surface integrity characterization is presented in this paper. This method consists of surface quality, surficial coat quality and the edge quality. Then an evaluation system of surface integrity based metrology is constructed and has been applied in a machining process of nickel-base alloy turbine disk. The manufacturing time decreased by approximately 10%. In all, this characterization and the evaluation system of surface integrity are rational and efficient. This work let us be capable of breaking through in the systematical evaluation of present machining surface.

Abstract: In order to increase load capacity of a heavy constant flow hydrostatic center rest, a theoretical study concerning the lubrication performance of the heavy constant flow hydrostatic center rest is described. The Computational Fluid Dynamics and the Finite Volume Method have been used to compute lubrication characteristics, such as the recess pressure and the oil flow state. The influences of oil-returning slot on the load capacity of the heavy constant flow hydrostatic center rest was analyzed based on the computational fluid dynamics and lubrication theory, and the influencing laws were revealed. Through this method, the reasonable data can be provided for optimal design and lubrication performance improving of the constant flow hydrostatic center rest in the heavy equipment.

Abstract: The key technologies of denture CAD/CAM system were studied in this study. Key technologies include: model acquisition, data processing, surface reconstruction, creating CAD models, establish standards tooth databases, rapid prototyping and CNC machining. The results show that the actual dentures feasibility of CNC processing systems and the denture model is validated. This study lays solid foundation for the development of the low-cost, lightweight and fast denture CAD/CAM system.

Abstract: Studying the core component of the resonant machine by building the bench test system, utilizing the nonlinear analysis function of Abaqus/Explicit to solve the problem that the rigid-flexible coupling model can`t take the material nonlinearity into adequate consideration. Simulating the nonlinearity of the vibrating beam by doing time integration over the kinematic equation to obtain an accurate and reliable result. Firstly, simplifying the bench testing system to simulating the low frequent vibration; And then, comparing the acceleration root value between the test data and the simulating result on the characteristically point to check the reliability and accuracy of the simulation; By studying the hammer vibrating amplitude curve and shear stress curve changing along the rubber spring thickness, providing a preference for the optimization.

Abstract: In this paper, the performance between cylindrical and twisted blades are analyzed for the same centrifugal pump. The three-dimensional steady and unsteady flow fields under 0.7Q_d, Q_d and 1.3Q_d are simulated. The blade inlet and outlet flow and pressure pulsation inside the centrifugal pumps are discussed by using mathematical statistics and frequency domain analysis methods. The research is verified by experiments. The results show that the twisted blade controls blade outlet better than cylindrical blade at small flow and design flow, cylindrical blade controls blade outlet better than twisted blade at large flow. In the blade inlet and outlet, as the flow changes, the instability of cylindrical blade loading is higher than that of twisted blade. The cylindrical blade inlet pressure is affected by the shaft frequency more than that of the twisted blade. At shaft frequency and blade frequency, pressure pulsation coefficient of cylindrical blade outlet is higher than that of twisted blade outlet. The cylindrical and twisted blades effect on the blade inlet and middle gradually accumulates, resulting twisted blade outlet has larger pressure pulsation. The result can guide the optimum design of centrifugal pump to consider the performance balance between twisted and cylindrical blades.

Abstract: Stress and strain at the crack tip are main mechanical parameters which estimate the stress corrosion cracking rate in metals, and the creep of metals in high temperature and high pressure environment will lead to the redistribution of stress and strain nearby the crack tip. The effects of creep on stress and strain nearby the crack tip are discussed by using 1T-CT specimen and finite element method in this study. The investigated results indicate that both increasing of temperature and stress intensity factor would induce the equivalent creep strain increases at the crack tip.

Abstract: We proposed a new method of measuring the residual stress for the component based on the acoustoelastic theory and focused on a new technology of making constant value block of residual stress by shot peening in order to solve problems of residual stress testing by ultrasound. Monitored the residual stress value of block by self-developed ultrasonic residual stress measurement system. The results indicate that the value of the test block changes not much, so it can provides a new way to improve the ultrasonic testing of residual stress.

Abstract: In order to reveal the failure mechanism of TiN coating, the simulations of scratch process with finite element method are carried out. Meanwhile, the stress analysis was carried out on the three stages that stylus tip indenting coating surface, slipping on coating surface and rising from coating surface. Through the observation of simulation results and the analysis of the stress shows that there are two ways of forming coating surface cracks. One is that coating interface cracks are firstly induced, thus they are propagated to the coating surface, and finally the surface cracks are formed. Other is that cracks are directly formed in coating surface. Because they are induced by maximum tensile stress, surface cracks are modeI.After stylus tip rising from coating surface, biggish residual stresses remain in the coating. Those analyses will supply the basis of coating design and application.

Abstract: Basketball skills have the features of difficulty, complexity, demanding, and being more difficult to master. For basketball, the flight trajectory of basketball and its stress analysis have become the hot issues researched by many experts and learners. And throughout the flight, basketball shooting naturally becomes the focus of our study. At present, there are a lot of shooting skills articles, but it mainly focuses on the skills analysis and implementation specification of action, and some evaluation methods of shooting psychology, also it lacks some quantitative theoretical study. Based on the elastic-plastic mechanics theory this paper explores the influence of air on basketball flight, which can provide a theoretical basis for the guidance of basketball this kind of ball sports in the future.