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

Abstract

To study the compressive mechanical properties of the hydroxyl-terminated polybutadiene (HTPB) propellant at high strain rates (700–1900/s) and low temperatures (−50 °C to 25 °C), we conducted a dynamic mechanical experiment using cylindrical specimens on a split Hopkinson pressure bar (SHPB). In addition, scanning electron microscopy was employed to observe the compressive fracture surfaces. The experimental results indicate the effectiveness of the proposed SHPB testing for the HTPB propellant. The effects of the strain rate and low temperature remarkably influenced the variations in stress. The lower temperatures and higher the strain rate generated an obvious increase in the modulus and compressive strength. Even at −50 °C and 1900/s, the propellant still maintained its viscoelastic characteristics. On the basis of the time–temperature equivalence principle, we obtained the master curves of the mechanical parameters. The propellant mainly exhibited transgranular fracture damage, increased porosity, and matrix tearing after impact. Keywords: HTPB propellant, Dynamic mechanical properties, Low temperatures, High strain rates