Fracture Characterization Model of Long-Rod Tantalum Alloy Explosively Formed Projectile Induced by Explosive Loading

Tantalum-tungsten alloy liners manifest intricate non-uniform deformation attributes during the formation of explosively formed projectile (EFP) with a significant long rod, eliciting heterogeneous deformation gradients at different positions. This phenomenon culminates in localized necking phenomena, precipitating structural failure and subsequent fracture occurrences. To address the elevated temperature, severe strain rates and intense strain conditions intrinsic to the fabrication of tantalum-tungsten alloy EFPs during formation, dynamic high-temperature and high-strain-rate split Hopkinson pressure bar (SHPB) tests were conducted. Furthermore, the integration of the Zener-Hollomon parameter facilitated the establishment of a nuanced correlation between dynamic mechanical parameters (including strain rate, strain and temperature T) and the activation energy Q of deformation for tantalum-tungsten alloy liner materials under the ambit of thermal-mechanical coupling. Leveraging the outcomes derived from LS-DYNA, a theoretical framework was devised to delineate a critical fracture characterization model for the Zener-Hollomon parameter in terms of strain, thereby facilitating the prediction of fracture occurrences. Notably, experimental validations underscored the efficacy of this model, thereby facilitating precise prognostication of fracture events. The findings of this study can guide the design of tantalum-tungsten alloy liners for long-rod EFP formation under explosive loading.