粉体粒度对松装粉体孔隙度影响的计算机模拟研究

本文应用离散元分析法(DEM),综合分析粉体颗粒受到的重力、分子力、接触力、摩擦力等多种力的作用,建立松装粉体颗粒的数学模型.使用计算机模拟技术对粉体颗粒的堆积过程进行仿真.利用回归分析得到堆积松装粉体孔隙度随着粉体颗粒粒径的减小而逐渐增大的关系.并对比分析了计算机仿真与实际验证实验的共同点和差异产生的原因,提出了可能...     

计算机模拟仿真在过程冶金中的地位和应用

计算机模拟仿真作为一种研究流动，传热和化学反应过程的方法，目前已在冶金等领域得到广泛应用并显示出良好的应用前景，结合冶金过程的一些特点概述数值模拟仿真的基本原理，区域离散化方法，求解技术及应用实例。     

计算机数值模拟技术在铸造中的应用

本文论述了发展铸造过程计算机数值模拟技术的意义,介绍了该项技术的基本原理,回顾了这项技术在国内外的发展概况,并对铸造过程计算机数值模拟技术的发展趋势进行了探讨。     

热轧高碳钢线材制造工艺的计算机模拟

编制了在 PC机上运行的、模拟高碳钢线材热轧和控冷时的温度和显微组织演变的计算机模型。应用该模拟软件可以进行高碳钢线材的“电脑试生产”:动态显示线材的温度场、奥氏体晶粒演变及奥氏体分解过程。预报82 B、82 A、72 A和 72 B钢 ,直径 5 .5～ 12 .5 mm线材的最终显微组织和力学性能。反之 ,根据 82 B、82 A、72 A和 72 B钢 ,直径 5 .5～ 12 .5 mm线材所要达到的性能指标 ,亦可提出相应的工艺参数控制范围。     

CO/CO2气氛下含碳球团还原动力学模型及其应用

分析了ＣＯ／ＣＯ２气氛下含碳球团的还原步骤,以此为基础建立了含碳球团还原动力学的微分方程组,并编制了相应的计算机程序,在验证了该数学模型准确性的基础,对ＣＯ／ＣＯ２气氛中含碳球团的还原行为进行计算机模拟,该模型全面考虑了ＦＡＳＴＭＥＴ工艺条件下还原过程中的各种影响因素,模拟计算结果与献「１」的实测结果相符合,证明了用此模型可以优化含碳球团的直接还原工艺条件。     

42CrMo棒材轧后冷却过程组织转变的计算机模拟

 针对国内某钢厂42CrMo棒材组织难以控制的问题,通过实测42CrMo棒材的等温转变曲线(TTT),结合相变动力学和热力学的知识提出了相关的组织转变数学模型,进而利用有限元分析软件ANSYS以及提出的数学模型,对42CrMo棒材轧后冷却全过程的温度场及组织转变过程进行了计算机模拟,所得温度场及组织转变模拟结果与实测结果吻合较好,较准确地反映了42CrMo棒材在实际生产中的温度场及组织变化,表明此方法对组织控制及冷却工艺制度的制定具有一定的指导作用,可大大减少试验浪费,经济及环保效益显著。     

沉积贵金属载体薄膜催化剂的计算机模拟研究

贵金属载体薄膜催化剂由于高效催化性及特殊的选择性而获得广泛应用,薄膜技术以及计算机模拟辅助设计日益成为其制备的新技术。文章评述了其制备技术的特性以及沉积机理的计算机模拟模型,并展示了其沉积过程的计算机模拟结果。     

变形金属再结晶过程计算机模拟

通过有限元方法和计算机模拟技术可有效模拟金属热加工和变形金属退火时的再结晶过程，计算金属组织演化和预报材料性能。介绍了目前再结晶计算机模拟的方法和模型-Monte Carlo(MC)法，Cellular Automation(CA)法，纯几何模型模拟，分组模型模拟和杂化模型模拟，重点分析了MC模拟法在均质和非均质形核，二相粒子对再结晶的影响，动态再结晶等方面的研究进展。指出用MC法模拟存在的问题，应用有限元法计算基本变形储存能和织构；建立含速率的再结晶形核和生长模型及耦合温度场模型的研究途径。     

阻流板对陶瓷燃烧器燃烧过程的影响

应用计算机模拟技术研究了热风炉陶瓷燃烧器的燃烧过程,在此基础上,比较了有、无阻流板两种不同设计情况下的气体流动特征,特别研究了燃烧器空气通道内有、无阻流板对燃烧过程的影响,发现阻流板可以加强煤气和空气的混合,进而在相同空气系数下缩短燃烧火焰的长度。     

SWRCH8A盘条轧制工艺的研究

采用物理模拟技术研究SWRCH8A冷镦钢在热加工过程的组织性能变化规律,建立该钢的连续冷却转变曲线(CCT图),并以此来确定SWRCH8A控冷工艺。     

新型H380级别高强度钢轨热处理工艺的数值模拟

通过计算机数值模拟计算对H380级别热处理钢轨的淬火过程进行了分析。钢轨热处理过程是一种鉴于等温转变与连续冷却转变之间的"连续等温转变过程"。计算表明:对于H380级别热处理钢轨温降控制在200～250℃,钢轨轨头相变温度不应超过620℃,轨头抗拉强度取样位置处珠光体组织相变温度不应超过650℃,相变孕育期为22～30 s,在此段加强冷却强度,降低珠光体组织相变开始温度。有利于钢轨轨头淬硬层的深化,提高该级别热处理钢轨抗拉强度。     

能谱仪在TC16合金相转变稳定性分析中的应用

两相钛合金相转变过程中,存在β稳定元素聚集,使β相趋于稳定的现象。采用能谱仪定量分析了TC16合金在780℃下分别保温0.5,1 h后的α相、β相中β稳定元素的含量,对比分析了合金中相转变的稳定程度。结合XRD相分析和SEM组织观察,表明退火过程中,保温1 h比0.5 h,合金的相转变更趋于稳定。     

A grain boundary phase transition studied by molecular dynamics

We have conducted a thorough investigation of the high temperature behaviour of crystalline interfaces in 2-dimensional close-packed and 3-dimensional f.c.c. Σ = 7 bicrystals using the atomistic computer simulation technique of molecular dynamics. Gibbs free energies of the bicrystals were computed using the determinant technique and a computer calorimetry technique which we describe. The thermodynamic properties of the boundary were monitored over a wide range of temperatures, up to the bulk melting point. We observed a first order phase transition of the grain boundary in the 2D and 3D bicrystals at temperatures well below the bulk melting temperature. At the transition temperature the crystalline grain boundaries are replaced by highly disordered liquid-like layers.     

Numerical simulation of solidification in an aluminum casting

This work describes the computer simulation of the solidification pattern in an aluminum casting. The Finite Element Method (FEM), adopting nonmoving mesh, was used to calculate the transient thermal field during phase transition. Integral averaging techniques were employed to calculate both the nonlinear heat conductionK(T) and specific heatC _p (T) functions for the elements of the domain; a temperature dependent functionC _p (T) accounts for the energy of the phase change. A complete computer program, with pre- and postprocessors, for Computer Aided Design of castings is also presented. Anad hoc experiment has been performed to verify the accuracy of numerical results.     

Functional capabilities of molecular network components controlling the mammalian G1/S cell cycle phase transition

The molecular interactions implicated in the mammalian G1/S cell cycle phase transition comprise a highly nonlinear network which can produce seemingly paradoxical results and make intuitive interpretations unreliable. A new approach to this problem is presented, consisting of (1) a convention of unambiguous reaction diagrams, (2) a convenient computer simulation method, and (3) a quasi-evolutionary method of probing the functional capabilities of simplified components of the network. Simulations were carried out for a sequence of hypothetical primordial systems, beginning with the simplest plausibly functional system. The complexity of the system was then increased in small steps, such that functionality was added at each step. The results suggested new functional concepts: (1) Rb-family proteins could store E2F in a manner analogous to the way a condenser stores electric charge, and, upon phosphorylation, release a large wave of active E2F; (2) excessive or premature cyclin-dependent kinase activities could paradoxically impair E2F activity during the G1/S transition period. The results show how network simulations, carried out by means of the methods described, can assist in the design and interpretation of experiments probing the control of the G1/S phase transition.     

不同型号Gleeble热模拟试验机比对试验

采用首钢集团有限公司技术研究院Gleeble 2000D型热模拟试验机和中国钢研科技集团有限公司Gleeble 1500型和Gleeble 3800型热模拟试验机进行了动态再结晶、静态再结晶和相变比对试验。结果表明,采用Gleeble 2000D型热模拟试验机测得的静态再结晶曲线存在波动和形态异常现象,但其与Gleeble 1500型和Gleeble 3800型热模拟试验机测得的动态再结晶和静态再结晶试验规律一致;无论是动态相变还是静态相变,采用Gleeble 3800型热模拟试验机测得的相变温度均高于Gleeble 2000D型热模拟试验机。     

Shape instability during precipitate growth in coherent solids

The effect of coherent elastic strain on shape instabilities during growth of a single precipitate in an elastically anisotropic cubic system is examined. A general phenomenological field approach to phase transformation kinetics is employed. Emphasis has been given to understanding the formation of concave interfaces of a coherent γ′ particle in the Ni-based superalloys. It is shown by a two-dimensional computer simulation that the infinite-range and highly anisotropic strain-induced interaction results in a shape transition from circle to faceted square with 10 habits and rounded corners at the early stage of growth. Then the divergence of solute atom supply at the corners enhances their growth which results in a concave morphology. Vanishing of the supersaturation (transition to the coarsening stage) causes a diffusional relaxation of the concave interfaces back into flat ones, indicating that the concave square is a nonequilibrium shape. A semi-quantitative criterion for the formation of concave shapes is derived. The concentration profile inside the misfitting particle is found to be nonuniform during its growth and coarsening.     

矩形断面环形件弯曲成形过程中弹复问题的研究

采用三维弹塑性有限元方法对矩形断面环形件冷态弯曲成形过程的弹复变形问题进行分析研究 ,通过对成型过程的计算机仿真 ,分析了在一定宽度和高度工况下弯曲成型后弹复变形的规律。对确定矩形断面环形件生产过程中主要成型工具的尺寸具有指导作用     

Computer simulation of structural transformations during precipitation of an ordered intermetallic phase

A computer the simulation of kinetics of precipitationof an ordered intermetallic phase from a disordered solid solution in a model binar two-dimensional alloy is considered. All diffusion processes, the concentrational delamination (clustering), ordering, antiphase domain boundary movement and coarsening, are described by the microscopic kinetic equations. The ordering transition of the first and second kinds are considered. It is shown that the conventional precipitation mechanism through nucleation and growth of an equilibrium ordered phase occurs only in a very narrow “strip” of the two-phase field in the phase diagram. In the remaining part, the decomposition always starts from a congruent ordering, which produces a transient nonstoichiometric ordered single-phase state with the same composition as the parent disordered phase and the same symmetry as the product intermetallic phase. Decomposition of the transient ordered phase occurs predominantly at the antiphase domain boundaries (APBs), which results in a two-phase morphology with layers of disordered films separating antiphase domains of the ordered phase. This decomposition is a result of a concentration instability on APBs, which is more substantial than the conventional homogeneous spinodal instability. Further morphological evolution after decomposition is controlled by coarsening, which reduces the order/disorder interfacial area. The predicted precipitation mechanism through a formation of a single-phase transient ordered state is general. It is expected in the most part of a two-phase field of a phase diagram of any alloy systems with intermetallic precipitates related to the parent one by ordering.