Study of the blast resistance and protection mechanism of polyurea-coated armor composite structures: experiments and simulations

This paper focuses on the blast resistance performance and protection mechanism of a polyurea-sprayed vehicle armor composite structure under blast impact. We study the blast resistance performance of a steel plate with composite structures in four different spray configurations, which depend on whether spraying occurs and the spray position on the steel plate. First, near-field airburst tests are conducted for four different sprayed types of composite structures for a 2-kg TNT equivalent, and then, the test conditions are simulated using LS-DYNA software. Based on the verification of the accuracy of the calculation model, the dynamic response of the back-sprayed structure at different standoff distances is compared and analyzed. The test and simulation results reveal that compared with other spraying configurations, the back-sprayed structure has better blast resistance, and the low impedance ratio of the front-sprayed structure is the major cause of the aggravation of the structure damage. With the decrease in the standoff distance, the deformation range and flatness factor of the structure are constantly reduced, and the damage mode and protection mechanism of the composite structure keep changing. The blast resistance performance of polyurea is mainly based on the energy absorption and storage during the tensile phase and the energy release and dissipation during the rebound phase. For the back-sprayed structure, the steel plate is always the main energy-absorbing structure. In a certain load range, the energy absorption ratio of polyurea is proportional to the strength of the blast load. Additionally, when the load strength exceeds the tolerance limit of the surface steel plate, the blast resistance of polyurea cannot be effectively exerted. In such a case, the damage modes of steel plate and polyurea tend to be similar.