The Study On Progressive Fatigue Damage Analysis Of Composite Laminates

Advanced composites are widely used in aerospace field due to their fine performance, such as high strength and stiffness, material anisotropic, good resistance to fatigue and good molding process ect. While, the aircraft always suffer changing load, so the main destruction form of the structure is fatigue damage. However, in practice the fatigue damage doesn’t occure in composite structures, because we often use static strength design to cover fatigue design by considering the complex mechanism of composites fatigue. In order to take full advantage of composites in weight reduction and improve performance of aircraft, it has important engineering value and theory significance to research the fatigue damage further in composites design.In this paper, based on the finite element analysis software ABAQUS to carry on the secondary development, write subroutines to realize the fuction of three-dimensional composite laminate fatigue cumulative damge FE analysis. Establish analysis model by modular designing, which contains stress analysis module, failure criterion module, material degradation module and fatigue damage equivalence accumulation module. A modified Hashin-Ye failure criterion is applied to predict the failure of the elements. The rules of Camanho material sudden degradation and a strength deradation coupled with stiffness degradation are used to modify element stiffness and strength. Then considering the fatigue damage equivalence, accomplish the FEA process of fatigue cumulative damage.Using the data of glass fiber reinforced composites fatigue test results, the S-N curves and stiffness degradation models in longitudinal, transverse and in-plane shear direction are obtained. These fatigue data are adopted in the simulation to simulate fatigue behavior and estimate life of six different lay-up laminates. The simulation results, including the fatigue life predicted and the residual stiffness, are coincident with the experimental results well except for the quasi-isotropic laminate.