有限差分法在铸造应力场模拟中的应用

Application of FDM in casting thermal stresses simulation

基于单向热-力耦合模型,用有限差分法(FDM)进行温度场模拟,将所求得的温度结果作为体载荷施加到应力分析的三维模型中,采用不同差分格式对控制方程进行离散,计算应力应变,开发出FDM/FDM铸件热应力场数值模拟系统.该系统使得铸造应力应变分析与传热分析使用同一FD网格模型,避免了采用不同模型进行热-力耦合分析时的结点匹配问题,减小由此产生的单元温度载荷传递误差.采用实际铸件进行了浇注实验和残余应力测试试验,模拟结果与实际情况一致,表明FDM可以用来模拟铸件残余应力的形成和预测热裂产生的倾向.

Based on unilateral thermal-force coupling model,the heat transfer was simulated by finite difference method（FDM）,then taking the temperature result as thermal load added onto the 3D model the stress and strain were calculated and various difference scheme were adopted to discrete the control equations.A FDM/FDM numerical simulation system was developed to analyze temperature and stresses fields during casting solidification process.When adopting FDM,thermal analysis and stress analysis can use the same FD model,which can avoid the nodes matching between different models and reduce the errors of thermal load transfer.To calibrate the simulation system,pouring experiments were carried out and residual stresses were measured.The experiment results were in agreement with the practical cases,indicating that the forming of residual stress can simulated and the occurrence of hot tearingredicted by FDM.