Dynamic Mechanical Behavior and Ignition Characteristics of DNAN-Based Melt-Cast Explosives

In order to study the dynamic mechanical behavior and ignition characteristics of a DNAN-based melt-cast explosive, quasi-static and dynamic compression tests, as well as passive confining pressure tests were carried out using a universal material testing machine and a split Hopkinson pressure bar (SHPB). Impact ignition test was carried out using a drop hammer. Scanning electron microscope (SEM) and industrial computed tomography (CT) were used to examine the morphology changes in the samples before and after loading. The stress-strain curves, ignition thresholds and damage characteristics of DNAN-based melt-cast explosive under different loading conditions were obtained. The dynamic mechanical behavior, ignition characteristics and damage mechanism of the explosive under different loading conditions were obtained. The results show that the dynamic mechanical behavior of the DNAN-based melt-cast explosive exhibits a strain-rate dependence, demonstrating more pronounced brittleness compared to typical press-loaded explosives, lower strength under uniaxial compression, and peak stresses comparable to those observed in multi-axial compression. The holes are the main initial damage form of the explosive. The holes are filled and compacted under compressive loading. The main damage mechanisms are transgranular fracture and interfacial debonding. Under coupled compress-shear loading, shear flow occurs in the charge and the particles are rearranged. With the increase of loading strength, the main damage mechanism changes from intergranular fracture to transgranular fracture. In the drop-weight impact ignition test, DNAN-based melt-cast explosives are more sensitive to compression loading. The maximum unreacted drop heights and peak stresses under compress and compress-shear loading are 500 mm, 556 MPa and 600 mm, 622 MPa, respectively. The primary ignition mechanism is likely attributable to either the adiabatic compression of bubbles or the thermal energy generated by the impact collapse of voids resulting from compressive damage.