Experimental Investigation of Compressive Mechanical Properties and Fracture Mechanism of AP-HTPB Base Bleed Grain

Abstract

The compressive mechanical properties of hydroxyl-terminated polybutadiene (HTPB) bonded ammonium perchlorate (AP) base bleed grain (BBG) was studied via quasi-static (8.3×10-5~8.3×10-1s-1) and split Hopkinson pressure bar (SHPB) experiments (1200~6600s-1) conducted at 28℃. Scanning electron microscope (SEM) was used to examine the fracture patter after dynamic experiments. All non-linear stress-strain curves consisting of linear elastic and post yield region indicate that strain rate has a significant effect on the mechanical properties. Original damage evolves at low strain rate because there is difference between true stress - true strain curves from the first and the second time of quasi-static compression tests. Hysteresis loop exists in loading and unloading procedure and it is clear that strain energy is dissipated in the form of thermal energy in the period of compression. The maximum deformation is up to 0.6 during quasi-static and SHPB experiments. The main fracture mechanism changes from dewetting to matrix tearing and AP fracture when the strain rate increases to 6600s-1 in SHPB experiments.