The Effects of Curing Process on the Damage Behavior of Additively Manufactured Fiber-Reinforced Thermosetting Composites

This work investigates the effects of high-temperature curing processes on the stress–strain and failure responses of additively manufactured aligned discontinuous fiber-reinforced composites (DFRCs). A micromechanical framework is used for finite element simulation of damage and failure in the three-dimensional (3-D) representation of DFRCs under mechanical and thermal loadings. Accurate constitutive equations are utilized to explicitly consider the fibers, matrix, and fiber/matrix interfaces within the composite’s microstructure. The coupled thermo-mechanical analysis available on the commercial nonlinear finite element software ABAQUS is used to accurately simulate the response of the studied DFRC when exposed to different curing temperatures and mechanical loading. All material and geometrical parameters of the microstructural representation are defined based on a recently developed 3-D printed aligned discontinuous fiber-reinforced thermosetting polymer. The curing-induced thermal residual stresses and damage are then simulated and validated against the experimental data. The effects of different curing processes on the initiation and propagation of different damage types and on the stress–strain response up to and including final failure are predicted. Also, the impact of the perfect versus cohesive interfacial bonding on the DFRC’s performance is examined. This work reveals that the DFRCs’ responses are significantly affected when residual thermal stresses due to curing are considered, providing guidance for better design, manufacturing, and analysis of such composites.