金属熔滴与基板碰撞变形的数值模拟

曾祥辉¹, 齐乐华^1,2, 蒋小珊¹, 杨方¹

1.西北工业大学机电学院;2.西北工业大学现代设计与集成制造技术教育部重点实验室



摘要:

为了保证熔滴沉积增材制造工艺中熔滴间的良好结合及成型精度,对熔滴与基板碰撞后的变形及凝固过程进行数值模拟研究.采用两相流模型,结合自由表面跟踪算法和凝固界面跟踪算法,建立了熔滴变形及凝固的耦合计算模型并求解.分析计算结果表明熔滴温度场变化与形态变形过程相吻合;熔滴与基板的接触部分瞬时就发生了凝固,因此凝固层半径和熔滴外观铺展半径相等,碰撞速度较熔滴温度对熔滴凝固形态的影响更大.提出了碰撞过程半凝固的概念,通过计算得到了半凝固状态的时间、铺展半径和凝固层高度等参数.相邻两颗熔滴结合,当前一颗熔滴处于半凝固状态时,其后一颗熔滴与之结合的效果最好.

关键词:  熔滴  形变  半凝固  有限体积法  数值模拟

DOI：10.11918/j.issn.0367-6234.2011.03.015

分类号:TG111.4

基金项目:国家高技术研究发展计划资助项目(2008AA03A238);高等学校全国优秀博士学位论文作者专项基金资助项目(2007B39);西北工业大学博士论文创新基金资助项目(CX200808,CX200906)



Numerical simulation of a metal drop in impinging on substrate

ZENG Xiang-hui¹, QI Le-hua^1,2, JIANG Xiao-shan¹, YANG Fang¹

1.School of Mechatronic Engineering,Northwestern Polytechnical University,710072 Xi′an,China;2.Education Ministry Key Laboratory of Modern Design and Integrated Manufacturing Technology,Northwestern Polytechnical University,710072 Xi′an,China)

Abstract:

To obtain good fusion and precision of drops during drop deposition increasing material manufacturing,the drop deformation and solidification after impinging on the substrate was simulated.Two phase flow model,combining with free surface tracking algorithm and solidification interface tracking algorithm,was adapted to built up the coupled calculating models for drop deformation and solidification.The results show that the temperature transformation of the drop agrees well with the shape deformation,and the part contacting with the substrate solidifies instantaneously as the drop impinges on the substrate.The solidification layer radius equals to the drop radius,and the effect of the impinging velocity on solidification is more than that of the temperature.A concept of semi-solidification was proposed,and the time,radius and thickness of frozen layer for semi-solidification drop were calcutlated.The fusion was in the good conditon when the former drop was in semi-solidification state.

Key words:  melted drop  deformation  semi-solidification  finite volume method  numerical simulation