Microstructure prediction of injection molded parts of particle dispersed thermoplastics by particle simulation method

A numerical method is presented to simulate the dynamics of particle dispersed systems in complex flows during an injection molding process of particle dispersed thermoplastics. The particle simulation method (PSM) is combined with a flow analysis of the finite volume method (FVM). In the PSM, a particle is modeled with an array of spheres. Each pair of adjacent spheres is connected and deformed by three types of springs; stretch, bend, and twist. The motion of particles under flow field obtained from the flow analysis is followed by solving the translational and rotational equations of motion for each constituent sphere. The mobility matrix for each particle is calculated to obtain the hydrodynamic force and torque exerted on each sphere. For the hydrodynamic interaction among particles, the near-field lubrication force is considered when the separation between spheres belonging different particles is close, but the far-field part is neglected. The method was applied to motion of fillers (fiber and talc) during an injection molding process of thermoplastics. The calculated motions of fillers were in good agreement with the experimental results.