Material modeling and solid phase forming of polycarbonate sheet

The Maxwell‐Voigt type mechanical model proposed by Haward and Thackray was further modified to describe the strain rate dependent stress‐strain behavior of polycarbonate under the uniaxial loading condition. Major modifications included effects associated with different hardening components of inelastic resistance and the related temperature dependent material behavior. The modified analytical model was shown to describe some of the important features of the stress‐strain behavior of polycarbonate specimens tested over the range of strain rates and temperatures. Using the stress‐strain relationship as input data; several finite element analyses were made to predict the behavior of polycarbonate sheets under a simple solid phase cup forming process. The computed strain distributions agreed reasonably with the measured values obtained from the gridded polycarbonate sheet that was formed at an elevated temperature. Some of the key assumptions that were used in the analysis are discussed.