【作者】 刘宏伟；

【导师】 李日；

【作者基本信息】 河北工业大学 ， 材料加工工程， 2007， 硕士

【摘要】 铸件充型凝固过程数值模拟是当前材料加工领域的研究热点。许多发达国家都拥有了自己的商品化软件,已经应用大生产实践当中,国内也出现了几款商品化软件,但与国外水平相比,差距较大。基于此,本文采用较新的技术建立数值模拟的基础框架,总体发展目标是开发出具有自主知识产权的具有国内外先进水平的铸件成型数值模拟软件。本论文研究开发了铸钢、铸铁砂型铸件凝固过程温度场计算模块及缩孔缩松缺陷预测模块,材料数据库模块、后处理数据可视化等模块,进一步完善了前处理模块,基本形成了完整的数值模拟软件框架。在温度场计算方面,离散模型采用显式直接差分法,采用温度回升法和等效比热容法分区段应用来处理潜热,界面换热系数采用等效界面换热系数,并编制了完善的温度场计算程序。在此基础上完成了铸件凝固过程孤立域的实时快速准确计算。对于一般铸钢件,采用孤立域即缩即补法来预测集中缩孔,用Niyama准则来预测缩松缺陷。对于铸铁件,采用凝固过程收缩、膨胀动态叠加法和最终区域的收缩膨胀法来预测缩孔缩松缺陷。模拟结果与实际铸件浇注结果对比基本吻合。在材料数据库方面,在全面分析比较当前各种数值模拟软件数据库,采用paradox进行数据库开发,完成了具有增加、删除、修改等功能的简易实用软件材料数据库,并将其成功嵌入到数值模拟软件中。在数据可视化方面,采用目前最先进的OpenGL技术,在C++Builder开发环境下,编制了完整的前处理、中间计算及后处理图形显示程序,使得图形能够实时快速平移、旋转、缩放、剖切等变换,实现了对铸件的全方位立体观察。并且实现了对铸造凝固过程的凝固状态的动态彩色化显示。在软件界面开发方面,本文利用C++Builder丰富的构件,编制了一个图形化友好的操作界面,并整合了前处理、可视化模拟计算、后处理计算结果显示和材料数据库等程序,使之成为一个操作简单,功能相对完整的铸造过程数值模拟软件。更多还原

【Abstract】 Numerical simulation for foundry process is one of the hot research topics in material processing. Many kinds of commercial casting simulation software built by several developed countries have been put into industrial application now, and in contrast, there are also several software poor of strong capabilities created by a few Chinese units. In this paper, by adapting development to the numerical simulation, a numerical profile software including modulus of temperature field simulation, shrinkage defects prediction, material database, data visualization, and etc has been developed. We have independent intellectual property rights for it.In temperature field solving module, the direct difference scheme was used for numerical discretization, and the temperature compensation method and equivalent specific heat method were used together to deal with the latent heat, and the equivalent coefficient of heat transfer was used to deal with the interface coefficient, so a temperature field simulation module was set up, and also the isolate hot spots during the solidification of casting can be traced rapidly and accurately just in time. For steel castings, ELSDM (Equivalent Liquid Surface Descending Method) and Niyama Method were applied to search the shrinkage and porosity defects; however, for iron castings, DECAM (Dynamic Expansion Contraction Accumulation Method) was employed. Then a few calculation instances verified the validity of them.For the database module in our software, by investigating several kinds of software from domestic or abroad, a thermal-physical database management system was developed on the base of PARADOX, with functions of adding, deleting, editing and querying data records in lists of the software database.In data visualization module, OpenGL, an advanced graphics technology, was adopted to set up the data visualization program under the developing environment of C++Builder. At last the functions such as the graphic’s real-time translation, rotation, and scaling were carried out, which makes it possible to perceive the whole casting from all aspects. In addition, the dynamic process of casting solidification in color display was achieved.In order to construct software interface, the abundant components of C++Builder was used, and then a friendly interface was built up, including the pre-process module, the temperature calculation module, the database system, and the post-process module. In the end, the easy operating casting simulation software was finished.更多还原