This study aims to investigate residual stresses in 3D printed objects using the fused filament fabrication (FFF) process. The FFF process involves melting a polymer filament and extruding it through a nozzle onto a print bed. In this study, the print bed is modeled as a rigid body that moves at a prescribed velocity, while the nozzle remains stationary. Non-Newtonian and viscoelastic material models are used to simulate the polymer flow through the nozzle. Although fully resolved simulations of the FFF process have been performed by other researchers, this study is unique in using a viscoelastic material model to predict residual stresses in the printed object. Non-isothermal, thermo-mechanical flow simulations are used to predict residual stresses, with the free surface resolved using the arbitrary LagrangianEulerian (ALE) method. The simulations investigate the effect of various printing process parameters, such as nozzle temperature, bed temperature, and printing speed, on the residual stresses. The results are validated through experiments and show qualitative agreement with the simulation results.