Three‐dimensional numerical simulation of injection molding filling of optical lens and multiscale geometry using finite element method

This article presents the development, verification, and validation of three‐dimensional (3‐D) numerical simulation for injection molding filling of 3‐D parts and parts with microsurface features. For purpose of verification and comparison, two numerical models, the mixed model and the equal‐order model, were used to solve the Stokes equations with three different tetrahedral elements (Taylor‐Hood, MINI, and equal‐order). The control volume scheme with tetrahedral finite element mesh was used for tracking advancing melt fronts and the operator splitting method was selected to solve the energy equation. A new, simple memory management procedure was introduced to deal with the large sparse matrix system without using a huge amount of storage space. The numerical simulation was validated for mold filling of a 3‐D optical lens. The numerical simulation agreed very well with the experimental results and was useful in suggesting a better processing condition. As a new application area, a two‐step macro–micro filling approach was adopted for the filling analysis of a part with a micro‐surface feature to handle both macro and micro dimensions while avoiding an excessive number of elements. POLYM. ENG. SCI., 46:1263–1274, 2006.