Finite element simulation on thermoforming acrylic sheets using dynamic explicit method

After optimising the critical material parameters obtained from hot tensile tests, a dynamic explicit software package, PAM-FORM™, is used to simulate the thermoforming process of polymeric sheet. A hyperelastic constitutive law based on the Mooney-Rivlin model has been successfully adopted to carry out the initial simulation on bubble inflation and to identify the material parameters. It has shown a good agreement of the deformation profile with the experimental results. In this paper, further investigations are concentrated on the thickness distribution analysis and the strain states of the bubble inflation along with a comparison to the results from kinematic Grid Strain Analysis (GSA). The numerical simulation of pressure forming of a cup, whose forming mechanisms have been explained reasonably well with the available Williams’ analytical solutions, is also presented. For a more academic case, the adaptive mesh refinement scheme has been employed in the simulation of thermoforming a complex-shaped rectangular container to well predict the wall thickness distribution. The final simulation results of the deformation at different stages of forming process and the analyses of final part geometry are also presented.