Modelling of the temperature and residual stress fields during 3D printing of polymer composites

Fused deposition modeling (FDM) based 3D printing) technique involves the fabrication of polymer parts using a thermal process which may induce residual stress, stress concentration, distortion, and the delamination between layers. This paper aims to investigate this defect on ASTM D638 polymer composite specimens. For that purpose, a 3D thermo-mechanical model that simulates the process of FDM capable of calculating stresses and temperature gradients during the additive manufacturing of polymer composites was developed. The 3D model considers the temperature-dependent physical properties of composites which consist of density, thermal conductivity, thermal expansion coefficient, yield stress, and Young's modulus. The simulated process includes the heating, solidification, and cooling phases. Different printed parts were analyzed and compared. The stresses vary continuously because of the temperature gradient occurring through the composite thickness. It appears that the concentration of stresses is higher if the temperatures during printing vary rapidly. Those stresses can favor the delamination between the layers of the printed part and the residual thermal stresses can cause an offset to the failure envelope.