Dynamic finite element analysis of photopolymerization in stereolithography

Purpose - This paper aims to introduce the principle of the mask exposure and scanning stereolithography (MESS) and to develop a simulation code to analyze the MESS process. Design/methodology/approach - Photopolymerization is a key reaction in stereolithography. It brings about molecular linkage and releases exothermic temperature. The shrinkage effect is the major cause of prototype deformation, and the shrinkage resulting from scanning and mask exposing is different. It is important to analyze the inaccuracy of each curing layer after the mask exposing in order to optimize the scanning parameters. A simulation code, based on dynamic finite element method, to analyze the shrinkage effect in accordance with scanning path and mask exposure pattern. A benchmark model has been proposed to validate the implementation of the developed code. Findings - The simulation results show that the developed code can analyze the deformation in laser scanning, masking exposing and the MESS process. In benchmark model study, the sharp corner shrinks faster than rounded edge in mask pattern curing. Although the profile scanning can maintain the high accuracy in the MESS process, the residual stress is easily discovered inside of the sharp corner. Originality/value - The developed simulation code can be applied for optimizing scan path and exposing time due to the analysis process in accordance with the drawing path and fabrication parameters.