铸造充型与凝固过程的变网格数值模拟研究

鉴于充型过程的模拟计算极为复杂，是铸造模拟过程中耗时最多的部分，为缩短充型过程计算时间，提高计算效率，提出了一种利用变网格进行模拟计算的新思路，即采用不同的空间步长分别模拟计算充型和凝固过程，在充型过程的模拟计算中采用比较大的网格，而在凝固过程的模拟计算中采用比较细的网格，并设计程序模块实现两种网格之间的转换和对应，使得充型过程结束时刻的大网格系统温度场能够精确完整地转换为凝固过程开始时刻的细网格系统的温度场。对这种变网格方法进行了验证，并对实际零件进行了模拟分析。结果表明，变网格方法是一种提高模拟计算效率的有效方法，这种方法能够克服充型和凝固过程采用统一的细网格进行模拟计算而产生的计算时间过长，效率低的缺点，使得铸造过程数值模拟的计算速度大大提高，而计算结果仍能满足工程实用的要求。

Study on a Varied Grid Numerical Simulation of Mold Filling and Solidification in Casting Process

The simulation calculation of mold filling is very complex and it is the most time consuming segment for the casting process. In this article the purpose of author is to reduce the calculation time and improve the calculation efficiency. A new idea of using varied grid to do simulation calculation was proposed. Different space-steps are adopted to simulate the mold filling and solidification processes respectively. Coarse grids are adopted in the simulation calculation of mold filling process and fine grids are adopted in that of the solidification process. Program module was designed to realize the transformation between the two sets of grids, making the temperature field of the coarse grid casting system at the end of mold filling transferred to the fine grid casting system as the initial temperature distribution precisely and perfectly. The method was verified by a sample casting and was applied to the simulation and analysis of casting practice. The results show that the varied grid method is effective to improve the efficiency of simulation calculation. The method can overcome the disadvantages of low efficiency caused by using the same fine grid system for both mold filling and solidification processes. The calculation speed is improved greatly and the results can still meet the practical requirements.