Research on the viscoelastic constitutive model of HTPB propellant over a wide range of strain rates

To investigate the rate-dependent mechanical properties of hydroxyl-terminated polybutadiene (HTPB) propellant, low(1.67×10^-4~1.67×10^-1 s^-1), intermediate(1~100 s^-1), and high strain rate (700~2 500 s^-1) compressive testing was performed, by using a universal testing machine, a hydraulic testing machine, and a split Hopkinson pressure bar (SHPB) system, respectively. Results indicate that the compressive mechanical properties of HTPB propellant are rate-dependent and the stress at a given strain increases with an increase in strain rate.Generalized nonlinear ZWT model was employed to describe the compressive mechanical behaviours of HTPB propellant over a wide range of strain rates.Compasrison of the predicted values from the model and the experimental data shows that the number of Maxwell elements in the model should be at least 4.