To accurately assess the ultimate strength of a hull girder, this study analyzes the elastic shakedown characteristics of hull stiffeners under cyclic loading.

Based on the results of nonlinear finite element numerical simulation, the average stress-average strain relationship of the stiffened plate element in Rahman's Beam-Column Method is corrected with full consideration of the elastic shakedown state, type of stiffened plate, and failure mode. A correction method applicable to the average stress-average strain relationship of the stiffened plate in the elastic shakedown limit state is proposed, and a program for Smith’s method for the ultimate strength of hull girders based on the elastic shakedown limit state is compiled and compared with the results of nonlinear finite element numerical simulation.

The results show that the proposed method can effectively evaluate the ultimate strength of a hull girder in the elastic shakedown limit state with greater efficiency than the nonlinear finite element method.

The application of Smith’s method for the ultimate strength of hull girders based on the elastic shakedown limit state can contribute to the accurate and efficient evaluation of the ultimate strength of hull girders.

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.

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.

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

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

In order to improve the accuracy of the ultimate strength evaluation of hull plates, this study carries out a nonlinear finite element numerical simulation of the ultimate strength of ship hull plates under cyclic loading based on the critical state of elastic shakedown.

Finite element software ANSYS is used to primarily investigate the effects of elastic-perfectly plastic and cyclic-plastic Chaboche material models on the release of welding residual stress and ultimate strength of hull plates after reaching the critical state of elastic shakedown.

The results show that after the first cycle, the welding residual stress is basically released and tends to become stable after reaching the elastic shakedown state under cyclic loading, at which point the ultimate strength of the Chaboche model is greater than that of the elastic-perfectly plastic model.

When performing the nonlinear finite element numerical simulation of the ultimate strength of ship hull plates under cyclic loading based on the critical state of elastic shakedown, it is necessary to select a material model that takes into account material hardening and the Bauschinger effect. The obtained results have a certain reference value for further research on the ultimate strength of hull structures under cyclic loading.