| When ships and Marine structures are sailing at sea,they will be subjected to loads if they encounter harsh environments such as storms and huge waves,The structure with small cracks in the hull will expand rapidly and fracture the internal structure.If it is serious,the whole ship will also fracture.Plates and stiffened panels are the most commonly used structures in ships and marine structures,which have strong rigidity and anti-cracking ability,However,in the service process,the plates and stiffened panels will produce tiny cracks,which will seriously threaten the safety of the hull structure,Therefore,it is of great significance to study the crack propagation of plates and stiffened panels for the safety and reliability of the hull and to repair the cracks in time.In this paper,the peridynamic method,a new method,is used to model the multi-cracked plate and stiffened plate,the static and quasi-static damage and dynamic damage analysis of the multi-cracked plate are carried out,and the dynamic crack propagation of stiffened panel is studied.The main contents of this paper are as follows:A crack plate program based on peridynamics method is developed,combined with the element stress extrapolation method,the stress intensity factor coefficients of crack tips of plates with central through cracks and single through cracks are solved,then the numerical solution is compared with the theoretical solution to verify the correctness of the crack plate program and the bond fracture program,then,the program is applied to multi-crack plates,and the stress intensity factors of unequal length double-crack plates are calculated and the related laws are summarized.The quasi-static problem of peridynamics is solved by the adaptive dynamic relaxation method,and the quasi-static loading program is written to analyze the quasistatic tensile deformation and failure of the plate with a circular hole and the non-collinear multi-crack plate.The simulated non-collinear crack propagation path is compared with the literature experimental results,and the correctness of the quasi-static loading program is verified.The correctness of the dynamic loading program is verified by comparing the crack propagation path of Kalthoff-Winkler experiment simulated by peridynamics with the experimental diagram in the literature.Then,the influence of different load rates on the failure modes of cracked plates is studied.The peridynamic model of parallel doublecrack plate is established,and the influence of crack spacing and arrangement of tiny cracks on the failure mode of multi-crack plate structure is analyzed.Then,by changing the crack angle,a cross-cracked plate model is established,and the ratio of the length of two cracks is changed to study its influence on the structural failure form.A model of ship hull double-stiffened plate with through cracks under tensile load is established,then,the effects of stiffness ratio of stiffeners,reinforcement spacing and initial crack length were discussed,PD can successfully solve the problem of dynamic crack propagation of stiffened panels under tensile loading,and can effectively predict the position where cracks stop propagation on plates and stiffeners,and the relationship between crack propagation distance and time of stiffened panels is obtained. |
