Development status of casting simulation technology

Casting simulation technology first rose abroad in the 1960s. Denmark, the United States, Germany, Japan and other countries have successively carried out research in this field. The simulation direction has gradually developed from the initial solidification process simulation to the later filling process, stress field and microstructure simulation. The development of foreign casting simulation technology has mainly experienced:

① Basic calculation stage. The focus of simulation research in this stage is mainly the distribution of temperature field and flow field in the casting process.

② Prediction research stage. Using the numerical simulation of the process scheme, combined with the analysis results, the possible defects can be predicted to optimize the process, and the microstructure can be simulated and predicted.

③ Optimize the process design stage. Integrating computer simulation and automatic control technology, it is combined into a series of industrial casting equipment.

In 1962, forsund and others in Denmark took the lead in using the finite difference method to simulate the solidification process of castings; Since then, many American scientists have also carried out research one after another. Keverian et al. Used the instantaneous heat transfer program to simulate the casting process of automobile cylinder block, and later verified it through experiments; Pehlke, a scholar, has further studied this field and established the temperature distribution diagram of the temperature value obtained from the simulation analysis and the measured temperature.

In the 1970s, the theoretical research of numerical simulation in Japan also developed rapidly. The scholar Dazhong Yixiong put forward the theory of direct difference method, which is more convenient than the previous finite difference method. Shinyama Yingfu put forward the method of using two-dimensional calculation instead of three-dimensional calculation, and put forward the basis for predicting shrinkage porosity and shrinkage cavity. At the same time, China’s casting numerical simulation research also began to start. Dalian Institute of technology and Shenyang Foundry Research Institute are the first representatives to start this research in China. They have carried out systematic research in the setting of material physical parameters and simulation quality criteria. The research results have also laid a foundation for the follow-up research and application of casting simulation technology in China.

In the 1980s, more progress has been made in solidification numerical simulation. The solidification process of cast steel roll was simulated by finite difference method, and the location of shrinkage cavity was predicted; The Japanese Foundry Society studied the flow characteristics of molten metal, accurately predicted the casting defects by computer simulation, and more focused on how to improve the practicability of simulation technology. During this period, China also began to study the numerical simulation of casting process. Guo kechen and Jin Junze of Dalian Institute of technology studied the method of simulating the solidification process of large castings by using the finite difference method and the characteristics of compiling the simulation program. The same source program was used to simulate two different large propeller castings, and the universality of the source program was realized. Considering heat transfer and other factors, Wu Hong and Zhang Yi established a comprehensive numerical model of three-dimensional numerical simulation in the solidification process of castings, which provides a reliable basis for possible casting defects in the production process of large castings.

In addition, in the 1980s, the numerical simulation of casting filling process and stress field began to rise. In 1983, Taiwanese scholar Huang Wenxing cooperated with the University of Pittsburgh in the United States to simulate and study the filling process of molten metal flowing into rectangular horizontal cavity and vertical stepped cavity by using two-dimensional fluid Calculation Software Mac, which opened a precedent for the research of casting filling process. In the following year, Desai et al. Used vortex function to study the relationship between temperature field and weak convection and the change of ingate temperature under forced convection. In the following years, the research on casting filling simulation was mainly limited to two-dimensional filling process. By the end of 1980s, the numerical simulation of filling process entered a period of rapid development, and the simulation object gradually developed from two-dimensional process to three-dimensional process. Lin et al. Used heat transfer and SOLA-VOF method to simulate the filling process of die casting and predict the possible cold shut defects in the filling process of die casting. Scholars Chen et al. Improved the traditional two-dimensional SMAC algorithm and improved its accuracy in dealing with fluid intersection problems in fluid flow calculation.

Although the simulation of stress field in casting process has been rising since the late 1980s, it is difficult to analyze the stress field because the process of analyzing the stress field is relatively complex and requires a variety of technologies such as fluid, heat transfer and analysis of high-temperature mechanical properties of materials. It did not make preliminary progress until the 1990s. At the 60th World Foundry conference held in the Netherlands, Toyota Corporation of Japan published an article on simulating the three-dimensional residual stress of automobile engine cylinder block with large-scale computer, marking that the simulation of casting forming stress field has been put into industrial practical application. The stress field simulation in China started late, and Tsinghua University, Huazhong University of science and technology, Shanghai Jiaotong University and other universities have made more achievements in this regard. Lin jialiu et al. Simulated the stress field of the solidification process of Cylindrical Castings by using the finite element software ABAQUS; Zhu riming and others simulated the residual stress distribution and deformation of gray cast iron machine tool bed by using the FDM / FEM joint route. Wang yeshuang and others made an in-depth study on the formation tendency and theory of hot crack, introduced in detail the intergranular bridging theory, HCS criterion and solidification shrinkage compensation theory, and made a prospect for the prediction of hot crack by numerical simulation in China in the future.

After entering the 21st century, the simulation of casting filling, solidification and stress field continues to develop in a deeper and finer direction. Karma et al. Deeply studied the quantitative phase field simulation method of solidification microstructure, and successfully used pf model to simulate the deep undercooling rapid solidification process of Ni alloy. Zhang Mingyuan and others innovatively combined projection method and level set method to capture the gas-liquid two-phase interface to accurately analyze the two-phase flow in the three-dimensional filling process of complex castings. Ogorodnikova simulated the stress field during the casting process of aluminum alloy wheel hub by low-pressure sand casting, and combined with the bending test, explored the influence of residual stress on the loaded wheel hub.