Flow Characteristics of a Thermoset Fiber Composite Photopolymer Resin in a Vat Polymerization Additive Manufacturing Process

Additive manufacturing vat polymerization has become a leading technology and gained a massive amount of attention in industrial applications such as injection molding inserts. By the use of the thermoset polymerization process inserts have increased their market share. For most industrial applications, strength and stiffness are crucial factors to a successful implementation of cured photopolymer thermosets. Hence, fiber-reinforced polymers have recently been introduced. The behavior and especially orientation of fibers during the vat photopolymerization process has yet not been fully understood. Research indicates an orientation within the manufacturing layer and efforts have been made to achieve a more uniform orientation within the part. A vat polymerization machine consisting of a resin vat and a moving build plate has been simulated using the fluid flow module of Comsol Multiphysics (TM). A moving mesh with hyper-elastic behavior was utilized to simulate the flow of the photopolymer during the lifting of the build plate after a successful curing of a single layer. The velocity profile can thereafter be used to estimate a prediction for the orientation of the short fibers added to the liquid photopolymer resin. The prediction can be used to identify potential clusters or misalignment of fibers and in the future allow for optimization of the machine design and manufacturing process.