Extreme deformations of polyurethane-urea elastomers

Abstract

The mechanical behavior of phase-separated polyurethane-urea (PUU) systems under extreme loading conditions have been addressed in this thesis work. A nonlinear constitutive model was presented employ- ing multiple micro-mechanisms for representing distinct physical properties from each of hard and soft domains. The highly nonlinear stress-strain behavior of PUU was well predicted with energy dissipation and shape recovery, rate-dependence, and Mullins effect for homogeneous deformations. Furthermore, dynamic responses of the material in extreme conditions have been addressed under high speed micro- bead impact test with good agreements between the numerical simulation results and the experimental data. This supports that our constitutive modeling framework has reasonable predictive capabilities for the large strain behavior of the PUU material over at least 9 orders of magnitude in strain rates (from 10$^{−3}$ to 10$^6$ /s).