Objectives  In order to improve the anti-explosion performance of ship structures subjected to multiple underwater explosion loading, and obtain a numerical method for simulating multiple underwater explosions is proposed.

  Methods  The dynamic response of the 45^# clamped air-back steel plate with diameter of 600 mm and thickness of 5 mm subjected to multiple underwater explosion loading was studied by a method of combining experiment and numerical simulation. The plastic deformation history of the steel plate was obtained and the basic law of plastic deformation was analyzed.

  Results  The results show that the morphology produced by plastic deformation of the 45^# clamped air-back steel plate subjected to multiple underwater explosion loading is spherical-like, and the deformation mode is mainly bending deformation and biaxial tensile deformation. When the amount of explosive and the explosion distance are fixed, the deflection increment of the center of the steel plate will be decreased gradually as the number of underwater explosion loading increased, and after the second explosion loading, the deflection increment will be third-order of the first explosion loading. When the total amount of explosive is constant, compared with the results of multiple uniform underwater explosion loading, both the deflection and thickness reduction rate of the steel plate after single underwater explosion loading are larger, and the maximum difference of the center deflection is 20.25%.

  Conclusions  The experimental results agree well with the simulation results, which can provide certain reference for ship protection design.