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• Four ceramic-metal hybrid structures were fabricated and researched. • Influences of ceramic size, boundary constraints and connection mode of the substructures were researched. • Effects of constraints on the influences of penetration position on the performance were studied. • Hybrid structure exhibit much better performance than TC4 plate of equal areal density. Ceramic-metal hybrid structures have drawn extensive attentions as a protective structure for their excellent protection performances to defend penetration. In the present investigation, four hybrid structures were experimentally and numerically studied to determine the influences of the constraints on ceramic on their anti-penetration performances. It was found that the penetration resistances of the hybrid structures were significantly affected by the size of ceramic, boundary constraint and connection mode of the substructures. Both suitable boundary condition and appropriate connection mode of the substructures could provide relatively strong constraints to the ceramic prisms to improve the performance, yet the connection mode of substructures affected the performance more significantly. However, the penetration resistance of the structure with ceramic tile was slightly affected by the boundary condition and connection mode of the substructures. In addition, all of four hybrid structures exhibited much better anti-penetration performances than that of monolithic TC4 plate with the equal areal density. The better performances of the hybrid structures with monolithic frame suggest that suitable frames can provide strong constraints on ceramic prisms, and thus can be potentially used to defend penetrations. [ABSTRACT FROM AUTHOR]

The dynamic responses of metal rings subjected to high strain-rate loading are important issues in the design of munitions and armaments. However, limited work has been conducted to investigate the fragmentation behavior and fragment size characteristics of metal rings subjected to internal explosive loading of a hollow charge. In the present work, specimens with different thicknesses of metal rings and different radii of hollow cores were experimentally and numerically tested. It was found that, during the expansion of metal rings, some slightly deformed grains formed near the inner surface. These deformed grains made the inner surface of the fragments step-like, and were precursors to rupture. Large and small voids could initiate within some relatively thick rings during the expansion of the rings, and some cracks initiated from these voids and propagated towards the outer surface and inner surface. The circumferential rupture strain decreased dramatically as the radius of the cylindrical hollow core increased. For the specimens with the same hollow-charge, the circumferential rupture strain decreased as the thickness of the metal rings increased. In addition, it was easier to form strain localizations at the inner surface when the specimen had a larger height of the metal rings, resulting in a smaller circumferential width of the fragments for the specimen with a larger height of metal rings. Based on the fragment size characteristics, a modified formula was established and validated experimentally and numerically. The results indicate that the proposed formula is accurate and reliable in predicting the average circumferential width of the fragments from metal rings subjected to internal explosive loading of a hollow charge. • Fragmentation characteristics of metal rings filled with hollow-charge were studied. • Fragment size characteristics of metal rings filled with hollow-charge were studied. • A formula was proposed to predict the average circumferential width of the fragments. • The formula showed good agreement with the experimental and numerical results. [ABSTRACT FROM AUTHOR]

• A novel fragment warhead with double casings sandwiched charge is proposed. • The different fragment velocities of each casing were measured by flash-radiography. • A formula was established to predict the fragment velocities of each casing. • The formula shows good agreement with the experimental and numerical results. • The fragment velocities of casing are affected by the size of the charge and casing. This work introduces a novel fragmentation warhead that can produce two groups of fragments with different velocity characteristics and strike the target sequentially. The two groups of fragments come from two separate casings in one warhead, and the different velocities of fragments from different groups are attained by having a charge compartment sandwiched between the two casings in the warhead. A theoretical analysis formula is established to predict the maximum velocity of fragment from each casing based on energy balance. The results of X-ray radiography experiment and 3D smooth-particle hydrodynamics numerical simulation indicate that the proposed formula is accurate and reliable in calculating the fragment velocity as long as the thickness of the inner casing is less than 30% the radius of the inner charge. The fragment velocities of warheads with different structure are further analyzed, and the results show that the fragments of the two casing exhibit greater disparity in their maximum velocity when more charge is packed in the sandwiched compartment instead of enclosed in the inner casing. [ABSTRACT FROM AUTHOR]

Abstract Ceramic-metal hybrid structures have attracted significant attentions as protection structures because of their high anti-penetration performance. In the present study, a ceramic-metal hybrid structure was constructed with a TC4 frame and ceramic prisms, and its anti-penetration performance and mechanism against a vertical steel projectile were investigated experimentally and numerically. The hybrid structure exhibited much higher penetration resistance than the TC4 monolithic plate of equal areal density. It was found that the high anti-penetration performance was mainly attributed to the frame in the structure, which confined the ceramic prisms and effectively improved their penetration resistance. Additional performance improvement was found to derive from the adhesive that bound the ceramic prisms with the frame. The TC4 frame and adhesive prolonged the dwell time of the projectile on the ceramic prisms and significantly dissipated the projectile kinetic energy. In addition, although the hybrid structure in this investigation was heterogeneous, its anti-penetration performance was affected less by the impact position than those of conventional hybrid structures. [ABSTRACT FROM AUTHOR]