STRENGTH ANALYSIS OF FIBER REINFORCED COMPOSITE LAMINATES WITH BIG CUTOUTS

As a heterogeneous anisotropic material, the failure behavior of composite laminate is very complicated. In order to meet manufactural and functional requirements, it is unavoidable to have cutouts on primary composite structures. However, it makes the failure criterions face new challenges due to the more complicated failure processes of composite laminates with big cutouts. In this paper the strength analysis of carbon fiber reinforced composite laminate with big cutout under unidirectional tension is studied by numerical analysis and experimental tests. Firstly, consider the composite laminates with different layups, such as0₁₀ unidirectional laminate,0/90₅ and±45₅ cross-ply laminates, and different circle cutouts, Hashin criterion and stiffness degradation model are applied to analyze the progressive failure process under unidirectional tension by numerical simulation to obtain the ultimate load and failure mode for each laminate. Furthermore, according to the numerical models, experiments are carried out based on 3D digital image correlation (DIC) method. Results show that the failure mode of fiber reinforced composite laminate with big cutout under unidirectional tension is a typical brittle fracture, and the crack onset happens to the high stress concentration area. In addition, the failure mode and crack propagation strongly depend on the ply sequences and the cutout size. Therefore, comparing to others,±45₅ cross-ply laminate with big cutout has the lowest ultimate load for its serious delamination failure mode. The bigger of the cutout size, the lower of ultimate load. After comparison of experimental and numerical results, it is concluded that the numerical simulation for strength analysis of composite laminate should be improved by further developed criterions.