铝合金轮毂低压铸造充型过程数学模型的简化及验证

以铝合金轮毂低压铸造充型过程为研究对象,在原有的SOLA-VOF算法基础上提出了内外区域分离简化算法,设计程序模拟了该铸件的充型过程。结果表明,内外区域分离简化算法具有运行时间短、计算效率高等优势,得到了与SOLA-VOF算法基本相同的模拟结果。     

低压铸造过程充型模拟简化模型的研究

为了提高低压铸造充型过程数值模拟的计算效率，根据低压铸造中充型的特点，提出了一种简化的充型过程数值模拟的数学模型。用铝合金轮毂铸件进行了充型过程的模拟验证，模拟结果与原有的非简化算法的模拟结果进行对比表明，采用该简化算法有效地提高了计算效率，所得温度场分布和不同时刻的充型形貌与采用原有的非简化算法所得结果基本一致。     

镁合金消失模铸造液模气隙尺寸的数值模拟

消失模铸造中充型的平稳性非常重要,充型越均匀铸件质量越好。使用SOLA-VOF计算方法模拟了镁合金在消失模铸造中的充型过程,计算了金属液和泡沫模样之间的气隙距离。结果表明液模气隙在充型过程中逐渐减小并趋向恒定值。。     

电磁泵充型过程数值模拟技术研究

介绍了电磁泵充型过程的工作原理及特点,以SOLA-VOF法为基础建立数学模型,对电磁泵充型过程进行数值模拟,采用水力模拟试验验证建立的数学模型。结果表明,计算结果与实验结果相吻合。     

压室压射对压铸充型流场影响的研究

为了考察压室压射过程对压铸充型过程金属液流动形态的影响,基于SOLA-VOF算法开发了包含压室在内的压射全过程充型模拟程序和料饼处直接充填模拟程序。并采用这两套程序分别模拟了阶梯块压铸件的充型过程,结果表明:浇道和型腔内的初始流动形态会随压室慢压射过程工艺参数的变化而改变,采用压射全程模拟更能准确的反映金属液在压室内、浇道内和型腔内的流动形态。     

低压铸造充型和传热过程的数值模拟

采用有限差分的方法,在Windows 95/98平台上开发了三维铸造充型过程流场和温度场模拟的软件Expert,对于流场的模拟采用SOLA-VOF算法。采用压力场和速度场的全局迭代方法,有效地改善了充型状态,缩短了计算时间。应用此软件对Benchmark试块和其他的低压铸造实际零件进行了模拟分析,结果与试验比较吻合。试验表明,该系统能达到优化铸造工艺设计的目的。     

低压铸造铝合金轮毂充型与凝固模拟

在低压铸造过程温度场及流场实验的基础上,开发了基于ＳＯＬＡＶＯＦ算法的充型与凝固过程数值模拟软件,对７２－４６轮毂铸件进行了模拟分析。结果表明,低压铸造充型过程中降温明显,准确的凝固模拟必须首先考虑充型。针对轮毂铸件的充型特点,开发了简化充型模拟软件。简化模拟得到的初始温度场与采用ＳＯＬＡＶＯＦ算法的模拟结果基本吻合,实现了为后续凝固模拟提供正确的初始温度场的设计目标。     

低压铸造铝合金轮毂充型模拟实用研究

根据低压铸造圆盘类铸件的充型特点 ,设计开发了一套简化充型模拟软件 ,应用于低压铸造铝合金轮毂铸件的充型模拟。模拟结果与采用SOLA VOF算法的模拟结果进行对比表明 ,充型过程及铸件温度分布合理 ,实现了为后续凝固模拟提供准确的初始温度场的设计目标。该简化算法运算时间短 ,可以满足实际应用中对运算时间的要求     

低压铸造铝合金轮毂充型模拟实用研究

根据低压铸造圆盘类铸件的充型特点，设计开发了一套简化充型模拟软件，应用于低压铸造铝合金轮毂铸件的充型模拟。模拟结果与采用ＳＯＬＡ－ＶＯＦ算法的模拟结果进行对比表明，充型过程及铸件温度分布合理，实现了为后续凝固模拟提供准确的初始温度场的设计目标。该简化算法运算时间短，可以满足实际应用中对运算时间的要求。     

铸型充填过程模型化及流动场数值模拟

使用SOLA－VOF算法求解瞬态流体流动,对测内浇口二维充型时的灰铁流态瞬时流动进行了模拟,对原程序中的某些缺点做了修正。如:型壁上缩陷的形成,插值单元不适当的松弛因子以及不适当的边界条件。将修正的SOLA—VOF格式同Patankar、SMACI和SOLA算法在次代因子、松弛因子和占用CPU时间方面做了比较。结果表明,SOLA-VOF是一种迅速而稳定的算法。     

胫骨生物陶瓷复合材料的微结构增韧机理

扫描电镜观察显示胫骨是一种由羟基磷灰石和胶原蛋白组成的自然生物陶瓷复合材料.羟基磷灰石具有层状的微结构并且平行于骨的表面排列.观察也显示这些羟基磷灰石层又是由许多羟基磷灰石片所组成,这些羟基磷灰石片具有长而薄的形状,也以平行的方式整齐排列.基于在胫骨中观察到的羟基磷灰石片的微结构特征,通过微结构模型分析及实验,研究了羟基磷灰石片平行排列微结构的最大拔出能.结果表明,羟基磷灰石片长而薄的形状以及平行排列方式增加了其最大拔出能,进而提高了骨的断裂韧性.     

面向零件形状的计算机图形库的开发

论述了CAD技术中参数化设计的三种建模方法，重点介绍了基于特征的参数化建模原理。在此基础上，分析机械设计中的机构结构，归纳出其零件的几何特征构成。设计了机构CAD图形库，并提出了该图形库生成步骤和人机交互界面。     

FeCrAIW电弧喷涂层组织的致密化研究

采用激光辐照对FeCrAlW电弧喷涂层的组织进行致密化处理,借助扫描电镜和X衍射对涂层的组织进行了分析.测试了涂层的显微硬度.结果表明:涂层组织致密度提高,孔隙率明显降低.随着激光扫描速度的增加,涂层的显微硬度降低.在较低的扫描速度下,涂层与基体之间形成互熔区,涂层与基体之间产生良好的冶金结合.     

Prospects of the Use of Synergetic Approach to Solution of Problems of the Science of Nanomaterials

A synergetic approach to solution of problems of self-controlled synthesis of nanostructures and creation of self-organizing nanotechnologies is considered in connection with the superproblem of creation of materials with functional properties resembling those of biosystems. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 55 – 61, July, 2005.     

Kinetics of the oxidation of metals — Influence of self-diffusion of metal

The importance of the self-diffusion of a metal during its oxidation by a gas is treated for the cases of nonstoichiometric oxides having either interstitial cation or cation vacancies. We have established a general relationship for the reaction rate when a mixed diffusion process occurs. From this relationship, we have shown that the pressure dependence can be different, according to whether the rate-determining process is the self-diffusion through the metal or through the product.     

Features of formation of the structure in production of blanks of disks of heat-resistant nickel alloys

Conclusions To provide a high level of mechanical properties in wrought blanks of cast ÉP741NP and ÉP962 alloys it is necessary to form controlled structures. A necklace-type structure formed in homogenizing isostatic treatment, subsequent thermomechanical working including alternation of the operations of deformation in the (+)-area and recrystallization anneals, and final heat treatment is preferable. The temperature conditions of all stages of thermomechanical working are strictly controlled, especially the final operation of deformation and heating for hardening. To eliminate hardening cracks and distortions it is necessary to use molten salts at t=600°C as quenchants. The use of multiple production operations makes it possible to significantly reduce the structural inhomogeneity related to inhertance of the original dendritic structure. However, the structure of the final semifinished product is nevertheless characterized by a difference in occurrence of the processes of polygonization and recrystallization between the former dendritic cells and the interdendritic spaces in deformation and heat treatment.To obtain structurally homogeneous blanks for gas turbine engine parts it is necessary to use basically new methods of remelting such as vacuum double electrode remelting and electron beam remelting with an intermediate vessel.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 25–29, December, 1991.     

Ab-initio calculation of enthalpies of formation of intermetallic compounds and enthalpies of mixing of solid solutions

A large number of ab-initio calculations of energies of formation of intermetallic compounds have been performed in the last 15 years. The currently used methods are listed. The paper presents a review of the aluminium based compounds which have been studied. Comparisons of calculated and experimental enthalpies of formation are provided for aluminim-3d and-4d transition metal alloys at equiatomic composition. The modelling of the enthalpies of mixing of solid solutions based on a given lattice is described.