MOLD FILLING ANALYSIS BY PARTICLE METHOD

典型的铸造缺陷是由于充型和凝固过程中金属熔体和空气之间的边界移动不充分造成的。采用基于欧拉系统的有限差分法、有限单元法等数值格式进行充型和凝固分析。由于有固定的网格系统，这些方法对于复杂的边界运动都会失效。本文将一种基于拉格朗日系统的质点方法应用于铸件充型和凝固问题。(1)研究了颗粒有效半径对计算精度的影响。(2)研究了调节颗粒间相互作用强度的权重参数的计算方案。(4)将粒子方法应用于二维凝固问题，得到了有限差分方法可能失效的精确结果。(5)将粒子方法应用于二维充型问题，得到了具有运动边界的流动与传热问题的精确结果。

Typical casting defects are caused by inadequate move of boundaries between molten metal and air during mold filling and solidification. Numerical schemes based on Eulerian system, i.e., Finite Difference Method and Finite Element Method, etc, are utilized for the mold filling and the solidification analyses. These methods will fail for complex boundary movement because of there fixed mesh system. In this research, a particle meihod that is based on Lagrangian system is applied to the mold filling and the solidification problems. As a result, followings are obtained.(1) Effect of effective radius of particle on calculation accuracy was investigated.(2) Calculation scheme for weight parameter that adjusts strength of interaction between particles was investigated. As a result it was clarified that summation scheme gives more accurate result than integration scheme.(3) Particle method was extended to heat transfer phenomena for applying to solidification analysis.(4) Particle method was applied to 2d solidification problem and accurate results were obtained for tapered casting problems that Finite Difference Method may fail.(5) Particle method was applied to 2d mold filling problem and accurate results were obtained for flow and heat transfer problem with moving boundaries.