Advanced Materials Research Vols. 199-200

Abstract: By the kinematic and dynamic characteristics analysis of hydraulic excavator’s working mechanism system, the system was divided into three linear varying cross-section beam elements by using Finite-Element Method, then the dynamic differential equation of hydraulic excavator’s working mechanism system was established. The built equation better reflected the intrinsic relationships among the mechanism parameters, load parameters and its nonlinear dynamic properties, and it reflected the dynamic performances which the previous equations didn’t, so it laid the foundation of the further studies of the intrinsic relationships among the dynamics characteristics and mechanism parameters, load parameters of hydraulic excavator’s working mechanism system.

Abstract: The new low alloy martensitic wear resistant steel 25Si2MnNi3 and steel 53Si2MnNi3 are developed, which hardness are about HB450 and HB600 respectively, the impact abrasive wear resistance of new low alloy steel relative to high manganese steel ZGMn13 is investigated on MLD-10 type impact abrasive wear tester under the different impact energy, and the wear mechanism is analyzed. As a result, the new low alloy martensitic steel which impact toughness is well always obtains better impact abrasive wear resistance than that of steel ZGMn13 under different impact energy, and the primary wear mechanism gradually changes from micro-ploughing and micro-cutting to micro-fatigue and micro-cracking with impact energy increasing.

Abstract: In this paper, air movement states within the cutter deck caused by high-speed rotating blades are studied, impacts on the mowing blade by the air movement are analyzed with the consideration of the cutter structure. It will provide important references for the blade optimal design. By Computational Fluid Dynamics (shortened as CFD) method, the high relative speed motion model between the blade and air flow is established, the flow field through the blade tip section are simulated, and the instantaneous movement of air flow around the blade can be known. By the analysis of the aerodynamic influence, the optimized design of the mowing blade can be achieved. The lawn mowing vehicle with the optimized blade can have a good and stable flow conditions when cutting the grass, the performance and the value of the vehicle thereby are enhanced.

Abstract: By the analysis and comparison of LPG motorcycle and LPG automobile, the similarities and differences of them are expounded. Based on the components and structure of LPG automobile fuel system, the LPG motorcycle gas phase positive pressure fuel system and LPG motorcycle liquid phase positive pressure fuel system are designed, and the advantages and disadvantages are analyzed and compared. The engine cylinder cover is enhanced and setted maze channels, so the liquid state LPG can be pre-heated using the remaind head of engine before enter the decompressor, the frozen of decompressor is solved effectively. The road trial and testing show that the LPG motorcycle liquid positive pressure fuel system is simple in structure, stabilize and reliable, the comprehensive performance can satisfied the demand of national standard.

Abstract: The inverted umbrella aerator is the key equipment of biological wastewater treatment technology, which have the effects of oxygenation, mixing and plug-flow. the design and optimization of the mixing impeller is most important to the efficiency of oxygenation.In this paper, the solid modeling and finite element analysis and optimal design of aerator blades was made based on the study of the oxygenation mechanism.Firstly, the working process of the blades have been studied through solid modeling, mesh generation and finite element analysis process, and the stress-strain finite element analysis was offered based on Nastran, which identified the weak links in the leaves. And more, the optimize and improve designs for the production was made,which set the foundation for the manufacture of the blades.

Abstract: In order to investigate the influence of combustion chamber geometry on spray and combustion characteristics in diesel engine, universal CFD software STAR-CD is applied to simulate the combustion processes in three different types of combustion chambers of diesel engine. The effect of combustion chamber geometry on in–cylinder air motion, temperature field and exhaust emissions are researched in this paper. Comparing with experimental results, calculation models are proved to be validity. The results show that differences of combustion chamber shape change the characteristic of flow field in cylinder, which affects the formation of mixed gas and determines the combustion and emission characteristics.

Abstract: Based on the operating characteristics of a micro HCCI (Homogeneous Charge Compress Ignition) free-piston engine, a multidimensional model which coupled CFD code, chemical dynamic model and piston dynamic model has been established. Using this model, an ignition and combustion process of the micro engine is simulated, the cylinder pressure and temperature profiles are obtained, and the influence of leakage and heat lost on micro engine combustion process is analyzed. Meanwhile, working characteristics of micro engine generator are evaluated by employing the simulation result. Power, combustion efficiency, etc of the micro engine are obtained. Lastly, the micro engine working characteristics with different load, fuel and piston mass are compared and effects of those varying conditions on engine performance are investigated. Simulation result provides essential requirements for micro free-piston engine control and design.

Abstract: Considering unsteady oil-film force and nonlinear rub-impact force, a dynamic model of crack and rub-impact coupling faults rotor system is developed. Based on the model mentioned, some parameters such as crack depth, eccentricity, as well as a combination parameter which consists of lubricating oil viscosity, rotor weight, bearing clearance and wide-diameter ratio are taken to be considered. According to the bifurcation diagram, the fractal dimension of poincare map and also the trajectory of the shaft center, the complex nonlinear dynamic behaviors are obtained, which may bring up theoretical references for fault diagnosis.

Abstract: Coal gangue is the waste of coal mining. It is discharged and stacked all around the mine and the dust pollution has become a public hazard. This paper commits an investigation on the asphalt mixture which takes advantage of coal gangue as coarse aggregate. The physical-mechanical performances of coal gangue aggregate are presented and the result indicates that coal gangue aggregate can meet the specifications except the content of the Flat and Elongate particles (F&E content). By controlling the rational content of F&E in the mixture, different types of asphalt mixes with different percentage of coal gangue coarse aggregate are tested and the overall performance of asphalt mixture is investigated. The result testifies that the asphalt mixture containing coal gangue has the equivalent performance with limestone mixture. It is observed that the coal gangue used as coarse aggregate can guarantee the properties of HMA. Thus the HMA can be used in asphalt pavement.

Abstract: After moving at high-speed & high-acceleration, the stacker column top’s deflection and vibration problem is of increasingly significance and must be solved. In this paper, through the establishment of stacker column mathematical model, the deflection and amplitude of column top are calculated and analyzed. After establishing a horizontal moving speed curve, the paper analyzes the changing status of column top’s deflection and amplitude utilizing Matlab. Finally, the paper determines using the control scheme based on this horizontal moving speed curve.