David Degenhardt develops an elasto-viscoplastic material model in order to predict the temperature and strain rate-dependent deformation and fracture behavior of thermoplastic polymers. The model bases on three supporting ambient temperatures, where a thermoplastic polymer has been characterized profoundly at the stress states 1) uni-axial tension and compression, 2) bi-axial tension and 3) shear. The core of the material model builds a pressure-dependent yield function with a non-associated flow rule. Further, it contains an analytical hardening law and a strain rate-dependent fracture criterion. The model is validated with components subjected to impact loading at different ambient temperatures. The comparison of the simulation and the experiments shows that stiffness, hardening, fractures strain as well as thicknesses can be well captured.

About the Author:

David Degenhardt is a calculation engineer in the chassis development department of a German automobile manufacturer and earned his doctorate while working at the Technische Universitat Carolo-Wilhelmina zu Braunschweig, Germany.