Research On The FEM Simulation Of The Liquid Infiltration-Extrusion Process For Fabricating MMC

The liquid infiltration-extrusion technology, as a new forming method of composites, has been developed in recent years. The process in essence is that after liquid metal is infiltrated into the fibre preform under pressure, high pressure is directly applied to it so that the melted metal is to be crystallized and solidified under pressure, and then underwent large plastic deformation near the entrance of the container. By means of this technology, shape products of metal-matrix composites can be formed in the single process. In this paper, the forming process of the liquid infiltration-extrusion of metal-matrix composites is simulated by the rigid-plastic finite element method for the first time, and then the temperature field, the stress-strain field and the deformation force are obtained. The infiltration process is simulated with similarity solution, and influence of infiltration pressure and volume fraction on the temperature field is revealed. During the simulation of the temperature field in extrusion process, finite element method is adopted in the space region and difference method is adopted in the time region. It is shown that pressure-maintaining time is the key factor that affects the forming process quality, and the steady semi-solid extrusion can be realized only if the metal in the deformation area is in quasi-solid state. During the simulation of the stress-strain field, method to deal with the liquid area and semi-solid area is put forward, the rigid-plastic FEM model of this technology is built. The stress-strain field of the whole deformation process is simulated by the re-meshing technology, and the changing process and influence factors of the deformation force are also studied. The numerical simulation results and the experiments are in a good accordance, which shows that the calculation model built in this paper is correct and provides a numerical simulation approach for the further optimization of the process parameters. The FEM modeling software that is programmed by utilizing the structure design method is made up of modules that are all-purpose and transplanting. The computation workload is reduced by the automated mesh generation in pre-processing, and the visibility of simulation results is improved by the convenient and practical post-processing. In this paper, the numerical simulation problem that includes high pressure infiltration, heat transportation, solidification and large deformation is solved successfully, which provides theoretic basis for the parameter optimization and the application of the liquid infiltration-extrusion technology.