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.

The process of liquid radial reflux interference during jet penetration in a liquid-filled composite structure is divided in this study into three stages: bottom plate reflection interference, side-wall reflection interference, and side-wall secondary reflection interference. The calculation model of the velocity interval of the disturbed jet and the residual penetration depth of the jet has been established through theoretical analysis. Results show that the liquid-filled composite structure can interfere with the high-speed section of the shaped charge jet. The accuracy of the theoretical analysis in this paper has been verified through numerical simulation, X-ray, and depth-of-penetration experiments. Among the results, those of the X-ray experiment show that the liquid-filled composite structure has interference on the tip of the shaped charge jet, which provides a possibility for the application of the liquid-filled composite structure to ammunition safety and other extreme cases.

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.

To study the ability of shaped charges to penetrate typical ship targets, two shaped charges with the same diameter of 200 mm but different configurations are designed to generate two forms of jetting projectile charge (JPC). Based on the protective structure of typical ship targets, static penetration tests are performed using the two types of a shaped charge with copper liner and 10-layer spaced targets with a total span of 16 m which is made in 921A steel. Numerical simulations under the same working conditions are also carried out. It is found that the simulation results of the penetration depth and the number of layers of target perforated by the JPC are much greater than the experimental results. In fact, the JPC breaks up when moving to a certain distance, and the JPC segments after breakup have a transverse drift velocity, causing the segment to deviate from the original penetrating channel. The influence of drift velocity after JPC fracture cannot be considered in numerical simulation, resulting in significant differences between numerical simulation and experimental results. Thus, this paper proposed a segment-based numerical simulation method and analyzed the penetration process of JPC fragments after JPC fracture. Combined with experimental results, the radial motion after JPC fracture and the final distribution of penetration holes can be well revealed. It is found that the penetration depth and the number of layers of target perforated by the JPC depend on the tip velocity of each segment and the jet length.