Thermo-visco-hyperelastic behavior of polycarbonate in forming of a complex geometry

Abstract

Abstract Thermoforming of polymers into intricate geometries entails deliberate control over material deformation to ensure the quality of the final product. Whereas current industrial practices primarily rely on trial and error approaches to identify the proper manufacturing parameters, simulation can expedite the process by offering insight into the interplay of different governing factors. In this paper, we develop a coupled thermal-mechanical finite element model to simulate vacuum thermoforming of a polycarbonate sheet into a finished product. We strive for a fundamental understanding of the interaction between polymer deformation and heat transfer processes that influence the thickness distribution in the final geometry. We employ a nonlinear thermo-visco-hyperelastic model for temperature- and rate-dependent behavior of polycarbonate along with a thermal contact conductivity at the interface of the mold and polymer. Thickness distribution of the simulated part matches well with the measured results of the manufactured part. Through simulation, we further explore certain strategies to redistribute the material in the final product. Our model, which accounts for essential mechanical and thermal aspects of thermoforming processes, provides a means to predict the quality of thermoformed parts in both design and manufacturing phases.