Key Engineering Materials Vols. 579-580

Abstract: For the high speed cutting process of hardened 45 steel (45HRC), a finite element simulation of cutting deformation, cutting force and cutting temperature is finished with the large general finite element software ABAQUS. Through the building of geometry model, material model and heat conduction model, also the determination of boundary conditions, separation rule and friction condition, a thermal mechanical coupling finite element model of high speed cutting for hardened 45 steel is built. The serrated chip, cutting force and cutting temperature can be predicted. The comparison of experiment and simulation shows the validity of the model. The influence of cutting parameters on cutting process is investigated by the simulation under different cutting depthes and rake angles. The results show that as the increase of rake angle, the segment degree, cutting force and cutting temperature decrease. But the segment degree, also the cutting force and cutting temperature increase with the increase of cutting depth. This study is useful for the selection of cutting parameters of hardened steel.

Abstract: The problem of diamond tool wear is the bottleneck for machining large metal reflector with ultraprecision cutting method. In this paper, the author performed simulation study on diamond tool wear in machining large metal reflectors, and established a molecular dynamics simulation model for dynamic simulation of tool wear; and found that in the simulation process the change in cutting speed and cutting depth had definite effect on the tool wear, and the main factors affecting the tool wear was the cutting distance.

Abstract: Automobile gear, as key part of automobile gearbox, bears the torque of automobile transmission, whose strength will directly affect the transmission efficiency of automobile gearbox and the service life of transmission system. On the basis of gear transmission theory, This paper focuses on gear pair of an automobile transmission as the research object, with the help of the professional transmission system software of MASTA, to realize the gear meshing analysis of the automobile gearbox, establish the simulation model of the automobile gearbox, simulate the actual load condition to complete the process analysis of the gear transmission. Finally, the strength optimization analysis of gear pair is implemented to obtain the reasonable gear design, which is more close to the gear meshing transmission process. There are great benefits to improve the overall performance of the automobile gearbox, effectively reduce the test cost, shorten development cycle, and optimize product structure. Therefore, it will provide guidance for the development and application of new transmission gear in the future, and present a new perspective and approach for the optimization analysis of gear strength.

Abstract: According to the real structure and work condition in recycling generating electricity project, a fluid-structure interaction (FSI) system model of high-flow control valve is set up. The flow and pressure in coupling and uncoupling condition are investigated. Representative points close to the valve are selected as control targets, the control accuracy of flow and pressure is studied. The impact of FSI on flow and pressure is analyzed. It has an important guiding significance for numerical simulation on FSI problems in the actual project to research on pressure and flow of control valve based on FSI. And it provides theoretical guidance for the optimization design and experiment of control valve.

Abstract: In order to solve the problem that the air flow was not average in the baking room, a new type of device called air flow-divider by this paper was designed. The physical model of the device was built by Solidworks. The influence of the device towards air flow was simulated by FloXpress. The result of the simulation indicates that the air flow was more even in the baking house after the new device was fixed.

Abstract: To make great use of recycled deserted solid and concrete confined by steel tube has been one of the most significant tasks for sake of green low-carbon production and environmental-friendly sustainable development, especially now, as the earthquakes in recent years have resulted in a host of deserted solids and concrete wastes. Engineering application of recycled-aggregate-concrete-filled (RAC-filled) steel tube is a new challenge facing humanity. Force of Steel tube components in practical engineering application is nonlinear and random. Owing to the difficulty in conventional method, it becomes a main subject to reveal the nonuniform axial force mechanisms of steel tube components. First of all, this article adopts finite element method (FEM) to simulate actual force, to analyze mechanics of axial force of steel tube components under uniform, nonuniform and eccentric conditions, thus building a mechanical model. Then the effect on the load capacity of steel tube caused by local factors such as steel tube components under different force conditions and deformation in the process of steel tube production is analyzed. Finally, the three force simulations of circular steel tube components in the diameter of 165mm, a wall thickness of 4mm and 2mm are carried out separately, it turns out that the error of component with a thickness of 2mm is 4.96% while the other is 7.35%. Obviously the simulation and experimental results fit relatively well. Besides, eccentric load is related to eccentricity: the larger the eccentricity is, the smaller the load capacity is. Moreover, it needs to be singled out that nonuniform capacity is greater than centralized eccentric axial load capacity. The research results demonstrate that different parameter selection,different force and manufacturing precision of steel tube and its component exert relatively high influence on load capacity of component. The results also indicate that variety of force conditions and deformation has to be considered in applications of RAC-filled steel tube. Thus, the research provides reference and basis for RAC-filled steel structure design and manufacturing.

Abstract: A FE model is built based on one vehicle door, the thickness of door's main components for absorbing energy is considered as the design variable. Firstly, a screening experiment is implemented by using Plackett-Burman design, and the prominent components for crashworthiness are selected. Then, the Latin hypercube experiment design is performed again. The approximation model of polynomial response surface is built by the Least Squares Regression according to the experimental results. At last, the approximation model, of which the objective function are the maximum internal energyand the minimum mass sum of all variables, and the constrain function is the maximum impact force, is optimized by using multi-objective Genetic Algorithm (MOGA). The results of the optimization show that the mass of all design variables and the max impact force are reduced by 4.12% and 4.43%, respectively, and the maximum internal energy is increased by 2.3%. The crashworthiness of vehicle door is improved, and it provides the technological support for the safety and light weight design of the whole vehicle door.

Abstract: Elliptical arcs have been widely used in stone contours, but the circular saw of the existing stone bridge cutting machine can only cut stone contours which compose of long lines and large radius arcs. The elliptical arc is often fitted by small line segments or small arc segments, and the circular saw cannot be used to process the stone elliptical arc contour. Therefore, a better choice of fitting the elliptical arc in the stone contour is the four-arc fitting algorithm. The traditional four-arc fitting ellipse algorithm can only fit the whole ellipse, in order to fit elliptical arcs, a new fitting algorithm of four-arc fitting elliptical arc is designed. Firstly, identify the stone contour and analyze the elliptical entities section from the DXF file, and divide the elliptical arc curve into several arcs according to the angular relationship. Then adopting the Chebyshev approximation theory of four-arc fitting ellipse, the preliminary fitting of the elliptical arc is performed, and re-fit the start section and end section of the elliptical arc curve, the elliptical arc fitting algorithm is designed. In addition, the maximum value of fitting error has been calculated. Finally, by using the Visual C++ as the developing software, the stone elliptical arc contour fitting algorithm and its processing trajectory simulation are realized. Testing results show that the fitting algorithm can meet the requirements of the circular saw cutting the stone elliptical arc contour.

Abstract: During the processing of the servo valve spool machining, the overlap of valve spool's each edge should take zero grinding. The grinding processes including spool overlap test and grinding. In this paper, the authors used a new test method, which simulates working condition of servo valve. Hydraulic cylinder is used as the load of servo valve in this test method, and the hydraulic cylinder is in no-load operation. This test method realized the automatic switch of test valve, and it determined the amount of grinding through complete measuring four edges overlap values, furthermore, it realized measuring the total amount of overlap, thus reflect the flow characteristics of a valve. This is a new automatic method for measuring servo valve overlap.

Abstract: Based on the CFD-FSI fluid-solid coupled method, the equivalent elastohydrodynamic lubrication model of the micro-texturing dimple surface on the condition of the medium velocity and medium load, low velocity and heavy load, high velocity and heavy load, low velocity and light load and high velocity and light load is respectively solved by numerical method in this paper. And obtain the oil film pressure distribution curve and the oil the film thickness distribution curve on the conditions of steady state, and analyze the influence of micro-texturing dimples on the bearing capacity of the equivalent elastohydrodynamic lubrication model. Analysis results show that: compared with the corresponding minimum film thickness on the conditions of smooth surface, the minimum film thickness of micro-texturing dimple surface on the conditions of the medium velocity and medium load, low velocity and light load is increased, which indicates the bearing capacity of the equivalent elastohydrodynamic lubrication model of the micro-texturing dimple surface is increased; while the minimum film thickness of the rest conditions is decreased, which shows that the bearing capacity of the equivalent elastohydrodynamic lubrication model of the micro-texturing dimple surface is decreased. The study in this paper lays the foundation for the design and optimization of the micro-texturing dimple.