An additively manufactured silicone polymer: Thermo-viscoelastic experimental study and computational modelling

The additive manufacturing (AM) is a new paradigm across various disciplines of engineering sciences. Despite significant advances in the areas of hard material printings, the options for 3D printed soft materials are still limited. Most of the existing 3D printed polymers are in the areas of acrylics and polyurethanes or their composites. Recently emerged Digital Light Synthesis (DLS) technology hugely accelerates the additive manufacturing of soft polymers. A DLS-inspired 3D printer uses a continuous building technique instead of a layer-by-layer approach, where the curing process is activated by an ultra-violet (UV) light. In this contribution, a DLS-based digitally printed silicone (SIL30) is experimentally characterized. To understand polymer's temperature-dependent mechanical responses, an extensive thermo-viscoelastic experimental characterisation at various strain rates under tensile deformation and temperature fields from -20 °C to 60 °C is performed. The study reveals significant effects of time-and temperature-dependency on the mechanical responses of the 3D printed silicone. Motivated by the thermo-mechanical results of the polymer, a thermodynamically consistent constitutive model at large strain is devised. Afterwards, the model is calibrated to the data that results in the identification of relevant parameters. The model predicts the experimental results with a good accuracy. 3D printed soft polymers are major candidates in designing complex and intricate architectured metamaterials for biomedical applications. Hence, a comprehensive thermo-mechanical experimental study and subsequent constitutive modelling will facilitate in designing and simulating more complex cellular metamaterials using 3D printed silicones.