Mechanical behaviors and equivalent configuration of a polyurea under wide strain rate range

摘要

The tension tests are systematically conducted on a polyurea by Instron and split Hopkinson tension bar apparatuses for strain rate ranging from 0.0001 s(-1) to-3000 s(-1), to investigate its mechanical behaviors. It is found that the polyurea presents a high rate-dependent, and the stress strain curves share a similar mechanical trend and consistent strain hardening coefficient trend under wide loading strain rates. The interrupted experiments are designed, and the results demonstrate that the polyurea is sensitive to temperature, which induces distinct softening influence on flow stress. However, the strain hardening coefficient is sharing the same trends and little influenced by the strain rate and adiabatic heating. The equivalent mechanical configuration is investigated by using the two-dimension unit cell model to simulate the polyurea mechanical characteristics. The systematical simulation results facilitate to outline its equivalent configuration: the soft phase dispersing in the hard network matrix. Furthermore, the matrix play a major role in the overall mechanical properties of polyurea. The configuration is further evidenced by the deduced data from reference. Finally, a simple analytical model is proposed with two components, and well capable of describing the mechanical characteristics including large strain behavior, strain rate effect and induced thermal softening effect.