In order to find new kinds of EFP liner materials with high density, W alloys, Ni, Mo, U, and U alloy were selected to be tested. Both liner test and flyer plate test were carried out in experiment, with existing EFP liner materials being testified as reference. It turned out that among the selected materials only Ni was suitable for EFP liner material, other potential candidates fractured to different extent in experiment. The potential reasons of materials’ fracturing under explosive loading were analyzed through different scales in fracture mechanics. Characteristics of a feasible candidate material for EFP liner were discussed through fracture toughness KIC, impact toughness αk, damage tolerance dy, and microstructure mechanics analysis. Finally material selection criteria of EFP liner were presented. The research results are significant in the material selection of EFP liner especially within high density materials, and it can be important guidelines for the researchers to avoid the blindness in research investments and waste in experiments in EFP research field.
This study aimed to investigate the interference of explosive reactive armor (ERA) on the penetration capability of explosively formed projectiles (EFPs). A numerical simulation model of EFP and the ERA interaction system was established. Flash X‐ray experiments for observing the interaction between EFP and ERA were performed. It turned out that the simulation method and material model was valid. From the numerical simulation, the residual depth of penetration (RDOP) of EFPs with different materials, scales, and shapes at several angles was evaluated, and the mechanism of ERA interference EFP was revealed. The results suggested that after an EFP passed through an ERA, its RDOP to target decreased with an increase in the angle and explosive layer thickness. The higher the density of EFP is, the stronger the resistance ability of EFP to ERA is. For copper EFPs, in the EFP charge diameter range of 90 mm to 170 mm, each 10‐mm growth in the EFP charge diameter results in an approximately 0.025 P0 increment in RDOP (P0 is penetration depth of EFP without ERA interference). Moreover, in the condition of the same mass, for each increase of 1 in the aspect ratio of the EFP, the RDOP increased by approximately 0.05 P0. In addition, calculation models for the RDOP, considering the charge diameter and EFP shape, were established respectively.
The microstructure evolution and plastic deformation mechanism of a Ta-2.5W liner under the ultra-high-strain-rate conditions generated by the explosive detonation were investigated in this study. For this purpose, a modular soft-recovery apparatus was designed to non-destructively recover the Ta-2.5W explosively formed projectile (EFP) in the ballistic endpoint. The electron backscattered diffraction (EBSD) method was employed to examine the microstructure of the Ta-2.5W liner before and after deformation. The microstructure of the recovered EFP exhibited significant grain refinement with preferred fiber texture. The theoretical computation results showed that the temperature of the EFP was in the range of 0.27–0.65 Tm. The deformation mechanism of the Ta-2.5W liner forming EFP driven by the detonation is the continuous dynamic recrystallization (CDRX) induced by high strain deformation, rather than the conventional dynamic recrystallization of nucleation and growth. The new grain structures evolve when the low-angle grain boundaries are transformed into the high-angle grain boundaries, and the specific grain refinement mechanism is the progressive rotation of subgrains near pre-existing grain boundaries.
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