Applied Mechanics and Materials Vols. 130-134

Abstract: The mathematical modeling and the kinematic simulation of the Tricept mechanism are finished by using the Pro/Engineer software in this paper. On the basis of the movement trajectory of the end point of the mechanism, the inverse kinematic and the kinematic curve of the Tricept mechanism are get, which are the basis of the control about the drive mechanism. In the meaning time, under using the Pro/Engineer, it is possible for us to control the motion of the end-point of mechanism which moved on the tangential plane. In order to avoid the tool to shimmy, the cutting output is constant in the course of processing which improves the process precision of the complex parts and provides the feasible and effective method for us to process the complex aerospace parts.

Abstract: It is a necessary step to break bags for bagged domestic waste before crushing it. This thesis carried out kinematic analysis for Whitworth mechanism, and put forward the requirements of shape of tool on account of the problem that materials (garbage) winded tools, In addition, it briefly discussed the design of avoidance device by Theory of Inventive Problem Solving (TRIZ). Preface Domestic waste refers to the solid waste generated in people’s daily lives. In recent years, with further urbanization, and the growth of population, domestic waste has been in sharp increase, so rational treatment of garbage has become a national sustainable development strategies related to the important issue. The main methods of waste disposal at this stage are landfilling, composting, incineration, of which landfilling is the most important. The level of domestic waste processing has a great gap between at home and abroad. As the processing technology has been started in Europe and other developed countries, thus, it is relatively mature, and the sense of residents’ environmental protection is stronger, the difficulty of waste disposal is reduced, so that the problems of waste disposal have been solved better. The research of waste disposal in China began in the 1980’s,and waste is bagged in the main form of garbage collection at present. On grouping garbage is so complicated and the equipments used to dispose garbage are insufficient, which can not meet the standards of waste reduction, innocuity and reclamation required by the government. At present, the garbage crushing equipment used in China is prone to twist, less efficient, poorly noisy, and adapt to different waste. Besides, it is easily over-fragment the unbreakable material such as glasses and used batteries, causing second pollution. Consequently, to develop new equipment for bagged domestic waste is of top priority.

Abstract: In the actual permanent magnet synchronous motor servo system, the load changes are a major factor that affects system performance. In this paper, a PMSM vector control system model based on speed sliding mode controller is established in Matlab/Simulink environment. By adjusting the parameters of controller, simulation and analysis are done on the load changes that may appear. The results demonstrate that the system is stable, with good load characteristics and Robustness.

Abstract: Jaw crushers are commonly-used machines in aggregate production. The aim of the research is to present a model which is able to predict particle size distribution in jaw crushers and to provide a new method for effectively controlling the quality of crushed product. The object of study was a domestic PEF 400×600 jaw crusher. A performance model was developed based on the standard mass balance formulation and chamber dividing results. Some important parameters that influence the particle output of the crushers were taken into account in the model. The variations of the particle size distribution resulting from changes in the eccentric shaft rotational speed and the parallel strip length were investigated.

Abstract: The radar antenna pedestal is a complex gear-bearing system including three rotary motions, i.e. horizontal rolling, pitching rotation and azimuth rotation. In this paper, spring-dashpot elements and connection elements are applied to simulate gear meshing and bearing connection respectively. Moreover, the equivalent average stiffness and damping of teeth meshing and bearing connection are calculated. Then, quadrilateral shell elements, hexahedral elements, wedgy elements, connection elements and spring-dashpot elements are employed to build the finite element (FE) model of the gear-bearing system in Hypermesh software. Via intermediate file, the model is imported into ABAQUS software for modal analysis whose solutions agree well with experimental data. Then, impact acceleration is imposed on the three bolts of the underpan along the x-axis, y-axis and z-axis respectively. Dynamic stress distribution and regulation changing with time under impact load are obtained. From the numerical solutions, the regions where stress and deformation is lager are found. The method can provide significant reference to analysis and optimum design of the similar system.

Abstract: Wheel drive motor torque ripple will cause noise and vibration, and affect vehicle ride comfort. The research status of electric vehicle wheel drive systems was described briefly. Based on the analysis and comparison of several electric vehicle motor, The causes of torque ripple in permanent magnet DC motors were summarized. Preventive measures of the torque ripple were proposed accordingly. Finally to be proposed were the new questions of the torque output characteristic of BLDC while used as the wheel drive motor in complex driving conditions.

Abstract: The high-precision component named full ceramic high-speed electric spindle is used in high speed NC machine tools. Electric spindle have very high demand for the stability and dynamic balance of ceramic spindle when high-speed rotation. In order to ensure the smooth operation of high-speed spindle and realize the dynamic balance of the spindle, it is necessary to make a rigorous precision testing for the precision-processed spindle and obtain reliable data to meet the design standards and performance requirements of all ceramic high-speed spindle. In this paper, contact Surtronic25 type roughness measuring instrument is used for surface roughness analysis, and Leitz ultra PMM-C12.10.7 type tri-ordinate measuring machine is used for the roundness and cylindricity testing analysis of spindle hole, which can make the surface roughness, roundness, and cylindricity of the precision-processed zirconia ceramic spindle pore ​​to meet the design requirements and provide reliability safeguard to promote the using life and high-speed dynamic balance stability of the whole electric spindle.

Abstract: Based on the nonlinear dynamical model of the gear system considering friction, the system periodic motion is studied by the Shooting algorithm, also the stability and bifurcation properties of the system periodic motion is obtained by Floquet multipliers. The system's evolvement properties are presented under different frictional coefficients. The conclusions are indicated that friction can influence the properties of periodic motion, which improves the stability of periodic motion on a certain extent, but produces new instability periodic motion. The conclusions provide a theoretical reference for designing of this system.

Abstract: In order to reduce the PAPR of OFDM system, DST is introduced into OFDM systems. DST will not cause BER deterioration and side redundant in OFDM system. In this paper, the performance of DST-OFDM systems is analyzed in theory. The simulation results show that DST method is better than conventional manners in PAPR reducing, system BER performance and implementation complexity.

Abstract: This paper explores the properties of Fe40NiCrSiAl alloy treated by different methods. The hardness, elastic modulus and resistivity are tested. The results indicate that: after LSP to rolled Fe40NiCrSiAl alloy, the hardness increased 25.22%, the elastic modulus increased 7.17% and the resistivity decreased 39%. TEM photographs demonstrated that there appeared dislocations, martensite transformation and twin crystals inside the material after being treated by LSP. Twin crystals are the main reason attributing to the improvement of material electrical properties.