Advanced Materials Research Vols. 189-193

Abstract: It is difficult to get an engineering accuracy answer of bending deflection for the profiled bar roller straightening according to elastic-plastic mechanics theory. In this paper, adequate mechanics model of profiled bar is established, combined with computer and mathematics, the relation between force and bending deflection of the profiled bar roller straightening is deduced. Compared with the traditional and engineering method, it is shown that the analytic solution accords with the production conditions and straightening theory and is a important reference for the establishment of technological parameters.

Abstract: In addition to the traditional test methods, numerical simulation the combustion process of internal combustion engine based on experiment, which have the advantages of short period, fast result, low cost and huge Information, has been an important means to study the flow field of engine and the effect of flow field to the emissions. The combustion process and emission characteristics of DI diesel were calculated using CFD software – FIRE. Some important research information, including the distribution of temperature field and exhaust emission concentration as well as the course of emission growth, were got and analyzed detailedly as a predictable reference for improving the structures and emission characteristics of existing DI diesel and developing the new combustion systems.

Abstract: In this study, the principle of the stretch forming combined with roll forming(SRF) is proposed, to present the availability of this process, it is simulated by the Method of Finite Element Analysis(FEA) by comparing traditional stretch forming(SF) with stretch roll forming (SRF), the result is shown that the roller covered the rubber rolling sheet metal is benefit to formed part, such as Von mises stress, the thickness thinned and the coincidence curve of formed part are studied.

Abstract: It is based on the comprehensive analysis of welding circuit for GMAW arc power, a system model, through power, cable, wire, droplet and arc, is created, and a voltage function of wire is also developed according to distributed temperature function about a variable of genuine length of wire. Then, a dynamic and multicycle droplet- voltage mathematic model is also found by the time-weight coefficient φ for the equivalent length of transferred droplet and by the transition of wire volume from a solid to a liquid state. Besides these, a arc-voltage function, involved the welding current, the genuine length of wire and the height of welding nozzle, is established logically and especially, Meanwhile, the correlative parameters is simultaneously analyzed. At last, there made an acute and good comparison between the oscillograms of simulation and experiment for voltage and current in the paper.

Abstract: According to tundish for thin slab caster in a steel factory, 1:3 water modeling and numerical simulation were established. By measuring RTD(Residence time distribution) curves of fluid flow in tundish, real residence time, plug flow volume fraction and dead zone fraction were computed, influence of turbulence controller structure on flow mode of molten steel in tundish were studied. The results show that fluid flow in tundish can be improved, if turbulence controller has reasonable structure. A reasonable turbulence controller structure was obtained. Water modeling results agree with numerical computing results well.

Abstract: In this paper, a two-dimensional nonlinear thermo-mechanical coupled finite element model was developed to simulate the vacuum hot bulge forming process of rotor-can with the aid of finite element software msc.marc. A set of stress relaxation experiments were conducted to test the high temperature creep properties of hastelloy c-276 and the creep law of material was defined. Then, the finite element model was used to study creep deformation of rotor-can during vacuum hot bulge forming process. As a result, the temperature field and the stress-strain field are calculated and analyzed. Furthermore, the effects of holding temperature and holding time on creep deformation are also investigated. The optimal holding time range for the vacuum hot bulge forming process of rotor-can is from 2h to 3h.

Abstract: This paper uses MATLAB Simlink module to simulate road spectrum of the blueberries farmland where blueberry harvesters are running, and gets white noise random road displacements. On the basis of ANSYS software, the finite element model of frame of blueberry harvesters is established to carry out imitative farmland random vibration analysis. According to the results from random vibration analysis, improves the structure of frame of blueberry harvesters.

Abstract: A three-dimensional mathematical model of growth, integrated with a new and effective algorithm for visibility checking, has been established based on a spray forming equipment with three different fixed atomizers in this paper. The model was used to predict the geometrical shape and the thickness profiles of the tubular deposit under various situations. By investigating and discussing the effects of different mandrel movement parameters and spray heights, the optimal atomizer of the equipment to fabricate a tubular preform was identified numerically.

Abstract: In deep drawing process, the experimental approach to obtain proper die-face design is not only expensive, but also requires much time and effort. Numerical simulation of the die-face design using expansion ratio analysis (ERA) can provide an avenue for lowering the cost and increasing the speed of the design process. A finite-element model of four-node quadrangle element is developed based on static implicit method using the Finite Element Code Marc. By the use of the model, the die-face design of oil pan deep drawing process is simulated. The relationship between the ERA and the maximum thickness variation is obtained. The smaller the ERA, the smaller the maximum thickness variation can be acquired. The mission success rate of the forming process increases, too. All the simulation results show reasonable agreement with the experiment.

Abstract: In-situ iron nanoparticles can be formed during copper alloy solidification. Here we consider ZCuSn₃Zn₈Pb₆Ni₁FeCo alloy and demonstrate that high undercooling is the motive power of nanoparticles during solidification , which would act as heterogeneous nuclei to achieve outstanding contribution for grain refinement compared to ZCuSn₃Zn₈Pb₆Ni₁ alloy. Convection of the melt inhibit the growth of nanoparticles by way of prohibitting the deposition of iron atoms on the surface.This technique offer new enlightenment for the control of in-situ nanoparticles formed during alloy solidification,and also opens the door to a new class of dispersed nanoparticles strengthened materials.