Abstract

Thermoplastic polymers nowadays are drawing attention in the automotive industrial thanks to their low cost, lightweight, and sustainability. They can be simply reshaped through the thermoforming process by heating up above their melting temperatures. Most thermoplastic polymers are semicrystalline ones that are composed of micro-spherulite structures with amorphous and crystalline regions. The amorphous region refers to the randomly distributed polymer chains whereas these chains are well-ordered lamellae in crystalline regions. These two phases interact with each other and result in a highly non-linear material response with the famous "double yield phenomenon". Therefore, to accurately predict the rate- and temperature- dependent semicrystalline polymers (SCPs) is still a challenge. Besides temperature increases due to the plastic dissipation under high-speed loading, inversely leading to the thermal softening and degrading the material performance. In this work, We proposed a thermomechanical modeling strategy for SCPs with a double yield phenomenon. Material characterization only requires few essential tests and the predicted results are promising.