Enhancing the blast resistance of building walls is a research hotspot in the field of anti-terrorism and explosion protection. In this study, numerical simulation and experimental verification were combined to analyze the failure phenomenon of brick masonry wall and sprayed polyurea-reinforced brick wall under contact explosion and determine the failure response parameters of the wall. The failure limit, mode, and mechanism of a 240 mm wall without reinforcement and strengthened with polyurea elastomer under different strength loads were investigated. Under contact explosion, the increase in the size of the blasting pit of the 240 mm wall gradually slowed down after the dose was increased to higher than 0.5 kg. Thereafter, the energy of the explosive load was released by splashing wall fragments as well as by deflecting and movement of the wall. The results show that the 240 mm walls sprayed with polyurea elastomer had outstanding anti-explosion performance because it wraps the damaged area and fragments of masonry wall inside the polyurea layer. When the thickness of the polyurea layer increases to 8 mm, the damaged area of the masonry wall decreases by 55.6% compared with that without reinforcement. The numerical simulation results were in good agreement with the experimental results.

No abstract

The liquid composite armour produces transverse interference to the sharped charge jet through the backflow of liquid in the inner cavity, which affects the subsequent penetration ability of the jet. Within this article, a single-cell structure filled with water is take as the research target. Through numerical simulation, the process of shaped charge jet penetrating the single-cell structure at different liquid level is reproducing, and the parameters of the remaining jet after penetration, the interference of jet, and the deformation and energy absorption of shell are obtained. The results showed that the liquid level of liquid-filled single-cell structure has a significant influence on the anti-jet penetration ability of the single cell structure. When the liquid level was 60mm to 65mm, the water-filled single-cell structure has the best interference effect on the incoming shaped charge jet.

The jet morphology of square and circular cross-section shaped charge with same inscribed circle diameter were observed by conducting an X-ray experiment. Depth-of-penetration tests at standoffs 80 and 160 mm were also carried out. The jet formation was studied by using AUTODYN software. The results showed that the jet of square cross-section shaped charge consists of a condensed part and a non-condensed part. The condensed part has similar characteristics to the corresponding part of circular cross-section shaped charge. And the non-condensed part is distributed at the jet tail. The non-condensed part consists of a main fluid moving along the axis and four off-axis fluids with off-axis velocity along the symmetry plane. The noncondensing of jet reduces the penetration depth of square cross-section shaped charge, the decreasing rate increased from 2.67% to 17.3% when the standoff is increased from 80 mm to 160 mm. When the inscribed circle diameter of the charge cross-section increases to 67.2 mm (1.2 times of 56 mm) and the liner structure remains the same, the square cross-section shaped charge will form a cohesive jet.

The coating of polyurea elastomers on walls is a hotspot in the protection field. This work combines a numerical simulation with experimental validation to examine the blast resistance after coating a polyurea elastomer on a 370 mm wall under a contact explosion. Firstly, the failure limit, failure mode, and failure mechanism of the 370 mm unreinforced wall under different strength loads are studied. In the case of the contact explosion, the increase in size of the 370 mm wall blasting pit gradually stops after the dose is increased to more than 1 kg. Thereafter, the energy of the explosive load wis released by splashing wall fragments as well as by the deflection and movement of the wall. Spraying double-sided polyurea reinforcement on the wall can effectively improve the resistance to damages caused by exposure to explosive loads and can inhibit the damage to the surrounding personnel and equipment caused by flying structural debris. When the polyurea thickness on the front surface is 6 mm, the optimal thickness of the back surface should be 2 mm.