Characterization of the Nonlinear Viscoelastic and Adhesive Properties of Polyurea and Characterization of Polyurea-Clad Metallic Structures

摘要

This report describes an experimental effort to characterize the viscoelastic properties of polyurea and the failure of ductile materials at high strain rates. The viscoelastic properties of cast polyurea were determined under monotonic loading conditions, both in the confined compression and Arcan shear configurations. The nonlinear viscoelastic properties have been determined and validated by predicting the large deformation compression behavior. Expanding ring experiments were performed on Al 6061-O, Al 1100-H14 and Cu 102 in order to investigate the onset and growth of necking localization and eventual failure at strain rates of about 3000 - 15000 per second. The modification of the failure behavior of these rings when coated with a polyurea layer was also examined at the same strain rates. It was demonstrated that while the polyurea did not alter the onset of localization, it did contribute to energy dissipation in the metallic ring by delaying the propagation of unloading waves in the metal. Adhesion between polyurea and steel substrate was characterized by a direct measurement of the traction-separation law.