CAE investigations of thermoforming process and its experimental validations

This thesis studied the sheet behavior during the drape forming and the air slip forming using an axisymmetric columnar male mold. The effect of anisotropic, residual stress and strain frozen in the extruded sheet thickness distribution, the sheet behavior after heating were experimentally studied followed by CAE analysis with a simulation package T-SIM® to examine the parameters for the thermoforming process. The simulated results with a uniform temperature profile showed a similar tendency, but differences with the experimental results. The consideration of the initial temperature distribution and the friction between the sheet and the mold was optimized to improve consistency of the simulation results with the experimental data. In this study, the optimal conditions consisted of initially 10% exceeding the original blowing height followed by de-pressurizing to the final height. This finding was simulated and the results drastically improved the accuracy; the great impact of the viscoelastic effect was verified.