Investigation of holed composite plates exposed to in-plane loading by the peridynamic theory

In this study, the damage behavior of holed composite plates under uniaxial tensile force was investigated. Composite materials, which have a more complex structure than isotropic materials, have an orthotropic structure, and when a discontinuity such as hole damage is added, it turns into a more complex problem. On the scope of the thesis the solution of these complex problems has been done with the non-local Peridynamic (PD) theory. PD theory is a theory introduced in 2000 due to the inadequacy of local and other non-local theories in modeling damaged structures. The properties that distinguish this theory from other theories, is the ability to solve nonlinear materials and damaged structures in one, two and three dimensions. The major advantage of PD theory is that it does not require a complementary relationship that determines when the crack should branch, stop, and orient randomly. The PD theory results obtained were confirmed by the Finite Element (FE) method, studies in the literature and experimental results. Firstly, an isotropic plate with centered open hole was studied under uniaxial bidirectional tensile load. The problem was examined without any damage with PD theory. The verification study of the problem was done by analytical and Finite Element Analysis (FEA). The stress and strain in loading direction and the displacement perpendicular to the loading direction are examined. The PD theory results for the isotropic open hole tension specimen were obtained very compatible with the analytical SEA methods. An open hole composite specimen which has been studied experimentally in the literature with the material T300 / QY8911, fiber angle of 90 ° and 12 layers were modeled with PD theory. The specimen dimensions, material properties, force and displacement were determined with reference to the experimental study in the literature. The problem is investigated undamaged and damaged. The undamaged problem is investigated under the force boundary condition and the results of normal stress and strain in the loading direction and displacement perpendicular to the loading direction are evaluated. The damaged problem was examined under displacement boundary condition and the reaction force when the plate was damaged and the fracture image of the specimen were obtained. Validation studies for the undamaged problem were conducted with analytical and FEA results and were found to be quite compatible. In the case where the damage was examined, the PD theory results were compared with the experimental data and were found similar. Thus, it has been shown that PD theory gives good results in modeling and damage estimation of composite structures with hole damaged unidirectional fiber angle and is applicable in this field.