Objectives   A simulation of steel/polyurea composite structures under close-range air blast loading was conducted, in order to study the improvement mechanism and analyze the influence of the polyurea backing layer on the blast-resistant performance of steel plates.

  Methods  The deformation/failure process and energy absorption mechanism of steel/polyurea composite structures under close-range air blast load-ing were numerically investigated, and the rationality and effectiveness of the numerical investigation were verified by related experiments. On this basis, the influence of the thickness matching and strength matching between the front steel plate and the back polyurea layer on the deformation/failure and energy absorption of the structure were analyzed.

  Results  The results show that the polyurea layer had two caving phenomena under blast loading, and the kinetic energy of the fragment was dominant in the total absorption energy of the polyurea layer. With the increase of the thickness matching between steel plate and polyurea layer, the deformation of the steel plate initially decreased, and then increased. With the increase of strength matching, the deformation of the front plate, and the energy absorption ratio of polyurea decreased monotonically. The kinetic energy of the fragment produced by caving was the main energy absorption mode of the polyurea layer. Under conditions of constant overall surface density, the steel/polyurea composite structure has the optimal thickness matching of anti-explosion performance. The increase of strength matching will decrease the energy absorption ratio of the polyurea layer, and the overall blast-resistant capacity will be improved.

  Conclusions   The research in this paper serves as a valuable reference for the future study of the blast resistance capacity of polyurea-coated 304 stainless steel plates.