Objectives In order to accurately assess the ultimate load-bearing capacity of a hull structure under cyclic loading, it is necessary to consider the effects of the cyclic properties of the load on the ultimate strength of hull stiffened plates.

Methods Finite element software ANSYS is used to carry out the numerical simulation of ultimate strength based on the elastic shakedown limit state under in-plane cyclic loading for 200 T-bar stiffened plates and flat-bar stiffened plates. The material Bauschinger effect, welding initial deformation and residual stresses of the hull stiffened plates under in-plane cyclic loading are considered in detail. Based on the stiffened plate nonlinear finite element numerical simulation results of the elastic shakedown limit state, the dimensionless ultimate strength of the stiffened plates is taken as the objective function, the flexibility coefficients of the plates and stiffeners are taken as the independent variables, and a formula for predicting the ultimate strength of hull stiffened plates under in-plane cyclic loading based on the elastic shakedown limit state is proposed.

Results The accuracy of the formula is verified through comparison with the nonlinear finite element simulation results.

Conclusions This study has positive theoretical and engineering significance for the ultimate strength assessment of hull stiffened plates under cyclic loading.