Damage response of polyurea-coated steel plates under combined blast and fragments loading

Steel plate structures have the potential risks of exposure to external blast/impact loading during their service. Spraying polyurea provides a simple way to enhance the impact resistance of existing steel plate members. However, the existing researches mainly focus on single load and lack of impact resistance of polyurea under multiple loads. Therefore, the damage response of polyurea-coated steel (PCS) plates under combined fragments and blast loading were experimentally and numerically studied. Cylindrical RDX charges with tungsten alloy balls were adopted to produce simultaneously fragments and blast wave, and the field explosion tests were conducted on three types of PCS plates with different configurations. The macro deformation and failure parameters of the PCS plates were obtained and analyzed, and the characteristics of five failure modes were defined. Some interesting experimental phenomena were obtained: whether the polyurea material was sprayed on the front-side or rear-side, the resistance capability of the PCS plates did not show a monotonous increasement with the increase of the polyurea material coating thicknesses, but there was an optimal thickness. Due to the unloading and overlying of compression and tensile waves, the damage degree of the steel plate in both-side sprayed PCS plate was higher than that of the single-layer PCS plate, and the two single-side spraying methods were superior to the both-side spraying method. Subsequently, the corresponding numerical models were established to reveal the dynamic response process of the PCS plates under combined fragments and blast loading, and the calculation results were compared with the test results of 3D scanning. Finally, the failure mechanism of the PCS plates was analyzed by the principle of energy absorption and stress wave propagation.