To meet industry’s ongoing and future expectations in terms of ceramic additive manufacturing for cutting-edge applications, a better comprehension of the stereolithography process and the resulting deformations on ceramic green parts is mandatory. Indeed, this curling effect, occurring especially on large parts, contributes to reduce the dimensional accuracy of this technique. In order to possibly reduce this issue, this work focuses on explaining the causes of these deformations, through a finite element modeling considering the specific features of additive manufacturing.
Two causes were identified as responsible, and thus, had to be considered in our model. First, previous works showed that the conversion rate of monomers is not homogeneous in bulk, therefore the resulting chemical shrinkage causes stress, especially between layers. Then, due to exothermic photopolymerization, thermal expansions and contractions are also involved in stress generation during non-uniform heating and cooling of the ceramic part. These two phenomena have been integrated into our finite element model, with the help of previous results from photopolymerization model, as well as material properties that needed to be investigated. In order to do so, the mechanical characteristics of green parts, depending on manufacturing parameters, have been obtained thanks to tensile tests associated with digital image correlation technique. This study allowed to predict the curl distortion of green parts in stereolithography process. These results pave the way to dimensional control and optimization of mechanical properties, even for post-sintering parts.