A 3d thermo-mechanical analysis of additively manufactured aligned discontinuous fiber-reinforced composites

This work investigates the effects of thermal residual stresses due to curing processes on the mechanical and failure responses of additively manufactured aligned discontinuous fiber-reinforced composites (DFRCs). A micro-mechanical framework is used for finite element simulation of damage and failure in the three-dimensional (3-D) representation of the DFRCs under both mechanical and thermal loadings. In this numerical framework, accurate constitutive equations are utilized to explicitly simulate the fibers, matrix, and fiber/matrix interfaces within the composite’s microstructure. All parameters of the micro-mechanical model are defined based on a recently developed 3-D printed aligned discontinuous fiber-reinforced thermoset. The coupled thermo-mechanical model on the commercially available nonlinear finite element software ABAQUS is used to accurately model the response of the studied DFRC when exposed to different curing temperatures and to mechanical loading. Intermediate fibers’ aspect ratios (FARs) and low fibers’ volume fraction are used, which are suitable for 3-D printed aligned DFRCs. The curing-induced residual stresses are then studied, and the effects of different curing processes on the onset of different damage types and on the stress-strain response up to final failure are predicted. Also, the effect 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 thermal residual stresses due to curing are considered, and therefore, provides guidance for better design, manufacturing, and analysis of such composites.