Numerical algorithm is the mathematical basis of numerical simulation of sand casting process. There are three common numerical calculation methods: finite element method, finite difference method and boundary element method. Different numerical algorithms deal with the boundary conditions differently, so the calculation efficiency and accuracy are also different. Among them, the finite element method is a widely used numerical calculation method, which is applicable to a wide range of disciplines and fields. It is more suitable to use the finite element method for sand casting system problems such as complex geometric boundary conditions and material nonlinearity.
The basic theory and method of numerical simulation of sand casting are introduced. The main contents are as follows:
- Due to the complexity of sand casting process, numerical calculation method must be used to analyze the filling and solidification process of sand casting. Three common numerical analysis and calculation methods of numerical simulation are introduced, and the ideas and methods of finite element method are summarized.
- The heat transfer basis of sand casting solidification process is introduced, the three-dimensional unstable heat conduction partial differential equation of solidification process is established, the crystallization latent heat of solidification process is analyzed, and the corresponding treatment methods are given. The formation mechanism of shrinkage cavity and porosity in sand castings is introduced, and the common criteria of shrinkage cavity and porosity and its implementation in software are given.
- The commonly used measurement methods of thermophysical parameters of materials are introduced, and the pouring method is introduced in detail, which lays a theoretical foundation for the determination of the test scheme.
By analyzing the heat transfer types and modes in the solidification process of sand casting, a three-dimensional mathematical heat transfer model in the solidification process of sand casting will be established; Then, based on the relevant elastic-plastic theory, the constitutive equation of the THERMOELASTIC-PLASTIC model is established, the formation mechanism and criterion of shrinkage cavity and porosity in sand castings are introduced, and the test methods of thermophysical parameters of materials are analyzed.