Compressive mechanical properties of HTPB propellant at low, intermediate, and high strain rates

Low, intermediate, and high strain rate compression testing (1.7 × 10^-4 to 2500 s^-1) of the hydroxyl-terminated polybutadiene (HTPB) propellant at room temperature, were performed using a universal testing machine, a hydraulic testing machine, and a split Hopkinson pressure bar (SHPB), respectively. Results show that the stress linearly increases with strain at each condition; the increasing trend of stress at a given strain with the logarithm of strain rate changes from a linear to an exponential form at 1 s^-1. By combining these characteristics, we propose a rate-dependent constitutive model which is a linearly elastic component as a base model, then multiplied by a rate-dependent component. Comparison of model with experimental data shows that it can characterize the compressive mechanical properties of HTPB propellant at strain rates from 1.7 × 10^-4 to 2500 s^-1.