Modeling of thermoforming process of HIPS polymer
Year: Sept. 2012- Jul. 2015.
Simulation of thermoforming processes is done with the aim of obtaining a part with best quality. Exact modeling of material behavior in the simulation has an important effect on+ improving simulation quality. In this research modeling of thermoforming process of high impact polystyrene (HIPS) was considered with the aim of proper modeling of material behavior and investigating effects of some process parameters on the simulation process. For this purpose Maxwell viscoelastic constitutive equation was considered and its constitutive equation was written in user subroutines UMAT and VUMAT in ABAQUS simulation software. Verification of the user subroutine was done with experimental data in literatures. Simulation of a rectangular polymeric part was done with the verified viscoelastic constitutive equation was done in ABAQUS. Results were in good agreement with experimental results. Effects of friction coefficient, plug velocity, sheet temperature and sheet dimension on the final part thickness investigated. By increasing friction coefficient, plug speed, sheet dimension and decreasing sheet temperature part thickness increases.
Keywords: Thermoforming, Polymer, ABAQUS, Viscoelastic materials, User subroutines