Biaxial compression mechanical properties of HTPB propellant under dynamic loading

To study the biaxial compression mechanical properties of hydroxyl-terminated polybutadiene (HTPB) solid propellants under dynamic loading, biaxial compression tests were carried out at room temperature (25 °C) with the strain rate ranging from 1 to 85 s−1 using an INSTRON testing machine with a new fixture, and microcomputed tomography (micro-CT) was used to observe the meso-damage of the loaded specimens. At the same time, a comparison test with a strain rate of 0.01 s−1 was carried out using a universal material testing machine. The experimental results indicate that the biaxial compression mechanical curves show strong nonlinear characteristics under all test conditions. Moreover, the mechanical properties of the HTPB propellant in biaxial compression are significantly affected by the strain rate, and the strain rate correlation of the HTPB propellant is controlled by different mechanisms with a strain rate of 18 s−1 as the demarcation point. Finally, from the analysis of microscopic theory combined with micro-CT reconstruction results, it is clarified that the strain rate correlation of the HTPB propellant is controlled by two different ways from the mechanism and that the effect of the strain rate on the mechanical properties of the HTPB propellant is closely related to its damage mechanism.