Revealing the influence of 3D printing density on the physical and mechanical properties of polymer articles

Abstract

This study investigates the process of 3D print-ing of polymer articles in light industry. The task addressed is to determine the stressed-strained state of 3D-printed articles made of PETG polymer, taking into account the nonlinear (inelastic) physical and mechanical properties of the material and the influ-ence of printing density on its mechanical behavior.The study’s result established that the tensile curve of 3D-printed samples from PETG follows the form of power function that reflects the properties of an inelastic polymer material. Applying the result-ing power function relationship between deforma-tions and stress, unlike the linear one, has made it possible to determine the normal stresses that appear in the internal layers of 3D-printed articles in the form of a beam of rectangular cross-section at bending. Numerical values were derived for parameters of the power function that reflects the dependence of stresses on strain when stretching 3D-printed sam-ples from PETG, manufactured at a print density of 70%, 80%, 90%, and 100%. It was found that with an increase in the density of PETG 3D printing from 60% to 100%, the tensile stresses in the samples increase from 12.3 to 19.6 MPa, while the relative deformation at their rupture decreases from 0.076 to 0.062. The resulting dependences make it possible to determine the required density of 3D printing to ensure the pre-defined limit load parameters for articles during their application.Taking into account the nonlinear nature of deformation and the influence of the density of the structure on tensile stresses and relative deformation at the rupture of the polymer material creates oppor-tunities for designing and manufacturing 3D-printed articles in light industry with predictable properties to enable their operability under operational loads.