Advanced Materials Research Vols. 712-715

Abstract: To improve the accuracy of roll flattening calculation based on semi-infinite body model, a more accurate roll flattening model is proposed in this paper, which is derived basing on boundary integral equation method. The lateral surface displacement decay functions are established. Based on the boundary integral equation method, the numerical solution of the finite length semi-infinite body under the distributed force is obtained and verified by Finite Element Method (FEM). Based on the new model, the error of semi-infinite body model is analyzed in different length-diameter ratio and non-contact barrel length. Quantitative relationship and the scope of semi-infinite body model are obtained.

Abstract: Based on analysis on the tip vortex in air refueling, a model for simulating the tip vortex of air refueling is established in this paper, and the simulation results is studied. The results show that the established model is suitable for different aerial environments and mission requirements.

Abstract: Recently, due to the reduction of oil and the deterioration of environment, people raised higher request for fuel economy and emissions, hybrid vehicle developed rapidly in most countries because of its low fuel consumption and emissions. In order to develop appropriate hybrid system, the text builds the model of prototype bus in the AVL-Cruise platform first, and then, establishes the model of PHB and accomplishes the control strategy of vehicle in the MATLAB/SIMULINK environment. The simulation data indicates: PHB can improve the fuel economy and emission performance effectively with guaranteeing a good dynamic performance of bus.

Abstract: Amplitude transformer is an important part of the ultrasonic vibration milling system. In this paper, a conical amplitude transformer is designed by the analytic method preliminarily firstly. Then its vibration modal is analyzed based on the finite element software ABAQUS in order to find the natural frequency of the amplitude transformer. At last the dimensions of the amplitude transformer with tools are modified through finite element method, so that an optimal vibration frequency is found, which makes sure that the amplitude transformer in the work vibration in longitudinal reliably.

Abstract: In order to reduce wheel profile wear of high-speed train and extend the service life of wheels, a high-speed vehicle multi-body dynamic model and wheel profile wear model are established, in which the wheelset is considered as flexible. The influence of wheel profile, track gauge, and rail cant is extensively studied. The simulation results show that the type XP55 wheel has smallest cumulative wear depth, and type LM wheel has largest wear depth. It is known that the equivalent conicity of the wheel should not be too large or too small. The track gauge with 1435-1438mm and rail cant with 1:35-1:40 can have better wheel wear performance.

Abstract: The dynamic mechanical responses of resistance welding machine,which is mainly governed by the mechanical parameters of the machine, is very important to the weld quality especially in projection welding when collapse or deformation of work piece occurs. In this paper, a mathematical model for characterizing the dynamic mechanical response of resistance welding machine and a special test set-up called breaking test set-up have been developed. Based on the model and the test results, the mechanical parameters of the machine were identified, including the equivalent mass, the damping coefficient, and the stiffness for both electrode systems.

Abstract: The chatter caused by the inner factors of the machining system in the ultrasonic honing process would seriously affect the surface quality of combustion engine. A dynamical model of ultrasonic honing chatter system was established, which involved with ultrasonic honing mechanism and dynamic honing depth, the relationship between the limit honing width and honing speed was deduced based on the theory of regenerative chatter; the simulation was carried out to obtain the effect of different parameters including stiffness coefficient, damping ratio, spindle speed and reciprocation motion speed on the stability limit curve of the chatter system. It can be concluded that the ultrasonic honing chatter system have better stability with low spindle speed, high stiffness and damping ratio, which providing foundation to eliminate ultrasonic honing system chatter in the precision machining of cylinder liner.

Abstract: Two identical segmented nozzles, consisting of graphite inserts and insulated with glass-fiber reinforced composites in the convergent and divergent sections, are used in the firing test at same operating condition. Due to the different thermal resistance ability, steps are formed at the interface of two materials. More specifically, the forward-facing step presents at the interface in the convergent section while the step in the divergent section is backward-facing and located at a certain distance downstream from the interface. This can be attributed to the opposite sequence of contact with the flow at the interfaces. The erosion rates, following the distribution of Reynolds number, exhibit an upward trend in the convergent section and decrease in the divergent section for both silicon phenolic and graphite. In addition, the graphite recession reaches the maximum value in the throat region. Along the cross-flow direction, the erosion rates are basically the same because the flow structure in the nozzle nearly axisymmetric. For the graphite nozzle insert, a correlation was developed in terms of chamber pressure, Reynolds number and nozzle geometry. The calculated erosion rates from the correlation showed agreement within 5% of the experimentally determined values.

Abstract: The two-dimension axisymmetric and two-phase flow in a full-size solid rocket motor with submerged nozzle under high acceleration condition has been simulated with Euler-Lagrange model. Without acceleration and under high axial acceleration on particle trajectories, the influences of different particle diameters were analyzed. The difference between gas flow field and two-phase flow field is significant. The particle accumulation zone above the inner wall of chamber and nozzle is mainly concentrated in two regions. The axial acceleration will intensify the impaction to the end of the chamber. The accretion of the particle phase diameter will increase the inertia of the particle phase, which may cause the following property worse, and the particles can easily form a highly-concentrated aggregation flow.

Abstract: Analysis of numerical simulation was used on flow field and temperature field in mechanical seal cavity. It borrowed a new calculation method, which was more visual and simpler than before. And this method analysed the change in temperature field of mechanical seal ring and the distribution of temperature and pressure in the flow field when mechanical seal was working. The result showed that the numerical simulation method was effect to the flow field in centrifugal pump.