Estudio numérico del comportamiento del poliestireno en el proceso de termoformado a través del modelo viscoelástico generalizado de Maxwell

Abstract

Polystyrene is thermoformed in a viscous state at temperatures corresponding to its crystalline melting point, in the range of 100 to 140 ° C. The mechanical properties of the material change with temperature since these plastics go from rigid at low temperatures to viscous when they increase. Under such conditions, properties decrease rapidly with temperature, and these variations in properties are the greatest difficulty during modeling. This study presents the findings during numerical simulations in which a viscoelastic characterization is implemented in laminated polystyrene. Experimental tests were carried out over tensile test specimens at different temperatures to compare results with experimental data. The generalized Maxwell viscoelastic model using Prony series was used to implement the simulation in a commercial finite element package. Once a fundamental numerical model was validated, numerical simulations that replicated the thermoforming process were extrapolated for more complicated thermoformed geometry configurations and different boundary conditions. The relevant agreement between the chosen model and the experiments allows studying the pressure, time, and temperature variations of the thermoforming process