Dynamic finite element analysis of photopolymerization in stereolithography

Abstract

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.

Analysis of new additive manufacturing technology based on selective composite formation using finite element method approach

“…In other methods which have been applied for vat polymerisation processes, light direction is only considered in one direction, where the light diffraction is neglected. Another point that is also important to be noted is that the polymerisation models are mostly related to penetration depth parameters and dimensionless coefficients (Jiang et al, 2006;Sharma, 2008). In these approaches, the behaviour prediction for different material formulations is difficult to be obtained only numerically.…”

A brief review of mechanical designs for additive manufactured soft materials

“…Wiedemann et al [46] also performed a numerical analysis on the SLA printing process and revealed a common rule where half the layer thickness doubles the curl. By relating the material modulus and cure shrinkage to the combinations of the averaged energy dose and curing time through several empirical equations, Huang et al [47] developed a dynamic finite element method to simulate the curl distortion of SLA-printed structures and found that short raster scanning produces less distortion than long raster scanning [Figure 2A]. The dynamic finite element method was later adopted by the same authors in another study in order to optimize the scanning parameters [48] .…”

“…Mechanical designs for the shape distortion of additive manufactured soft materials. (A) Schematic of the rezoning technique in the dynamic element method simulation of SLA-printed parts [47] . (B) Schematic and experiment result of the deformation of a twolayer resin laminate [40] .…”

Quantifying Geometric Accuracy With Unsupervised Machine Learning: Using Self-Organizing Map on Fused Filament Fabrication Additive Manufacturing Parts

“…Subsequently, the authors use virtual geometric models to characterize thermal deformation in terms of GD&T characteristics. Jiang et al proposed a simulation model to examine the inaccuracy of the mask exposure scanning stereolithography process [24]. Based on the simulation results, the authors suggested an optimal scan path and exposure time.…”