Research On Simulation Method Of Fatigue Crack Growth Of Stiffened Plate Structure Based On XFEM

Fatigue crack propagation is one of the main causes of failure of engineering structures,and stiffened plate structure as a basic unit structure is usually the main research object of scholars.At present,the problem of fatigue crack propagation with long span in stiffened plate structure with cracks has been paid extensive attention by scholars,and its propagation characteristics are also difficult to study,which is manifested as: a large number of crack tips,crack propagation across ribs for many times,and great loss of safety strength of the whole structure,so it is of great engineering significance to master its propagation mechanism and fracture characteristics.XFEM is a promising numerical analysis method,but it can’t solve the above problems properly at present.At the same time,it has some defects when embedded in commercial software.Therefore,it is necessary to put forward a numerical analysis method suitable for fatigue crack propagation analysis of stiffened plate structure with cracks on the basis of retaining its advantages.In this paper,based on ABAQUS＿XFEM module,the numerical simulation method of fatigue crack propagation of stiffened plate structure with cracks is studied,and related work is carried out in the aspects of accurate solution of stress intensity factor,identification of stiffened plate structure configuration,location of crack tip,simulation method of crack span process,etc.,which can realize accurate simulation of fatigue crack propagation at multiple crack tips and fatigue crack span.At the same time,the accuracy and rationality of the method are proved by carrying out tests and selecting test examples for verification.Firstly,the theoretical basis of crack growth is introduced,and the advantages of XFEM in crack growth analysis are demonstrated,as well as the reason of choosing three-dimensional interaction integral to solve stress intensity factor.Secondly,the simulation method of fatigue crack propagation of stiffened plate structure with cracks based on XFEM is put forward,and the secondary development work is carried out with ABAQUS＿Python script language as interface.the foothold of the research content is introduced in turn from three main aspects: the research on convergence and precision control method of stress intensity factor,the research on crack tip location and identification method of spatial three-dimensional structure and the research on simulation method of crack propagation across ribs.Finally,combined with cycle-by-cycle life calculation method,the complete framework and flow chart of fatigue crack propagation analysis of stiffened plate structure with cracks are given,and the propagation path and propagation life of different crack tips at different positions are effectively evaluated.Then,four kinds of composite fatigue crack growth tests of rectangular plates with holes are designed and carried out.The algorithm is applied to the numerical simulation of fatigue crack growth analysis of each specimen and compared with the test results,which verifies the correctness of the method,and the error level also reflects the high accuracy of the program in calculating stress intensity factors.Finally,the proposed algorithm is applied to the numerical analysis and verification of fatigue crack growth tests of stiffened plates with combined cracks,integrally stiffened panels with central cracks and honeycomb metal sandwich plates in turn.The results show that the proposed method has good simulation accuracy for different structural forms,different number of crack tips and different behaviors of cracks across the reinforcement,which fully verifies the accuracy and robustness of the proposed method.