Numerical simulation model for the curing of photosensitive acrylate resin in a stereolithography process

Controlling the precision and mechanical cohesion of 3D-printed parts remains a central concern in the development of additive manufacturing. A two-dimensional finite element model of the photopolymerization of a complex sensitive resin, formulated with three monomers to better represent commercial resins, in a stereolithography apparatus is proposed as a tool for predicting and optimizing formulation of photosensitive resin and its printing parameters. By considering light illumination, chemical reaction, and heat transfer in a resin exposed to a moving ultraviolet (UV) laser source, this first approach accounts for monomer-to-polymer conversion and polymerization rate in agreement with experimental results obtained by Fourier-transform infrared spectroscopy (FT-IR) monitoring and the use of semi-empirical models. The temperature gradient along the exposed photosensitive material was also estimated. By varying the photoinitiator content and simulating the addition of an absorbing filler via the molar extinction coefficient, it was shown that a higher photoinitiator concentration and the presence of strongly absorbing fillers lead to a reduction in the light penetration depth, which can result in structural defects without adaptation of the layer thickness to be printed.