Issue 35

M. Bozkurt et alii, Frattura ed Integrità Strutturale, 35 (2016) 350-359; DOI: 10.3221/IGF-ESIS.35.40 352 is also used for these surface couples. Between the bolt surfaces and hole surfaces on the specimen standard contact with friction is used. Finally, the standard contact type with friction is also used between the loading pins and the surfaces of the loading holes on the apparatus. Figure 3 : Decription of boundary conditions for mode-I/III fracture test system. In Fig. 3, the boundary conditions and loads applied on the model are shown. As shown in the figure, side surfaces of the the upper pin is fixed, while those surfaces of the lower pin are allowed to move only in the vertical direction with a total of 10 kN load applied in the same direction. This model, which contains the described contact definitions, boundary conditions and loads, is solved within ANSYS [6]. Then, the compact tension tearing specimen is isolated, its displacements on the connecting surfaces are re-applied to it and re-solved as a fracture mechanics problem using FRAC3D, i.e., submodeling of the CTT specimen is done. From this analysis mixed mode stess intensity factors are obtained. Fig. 4 shows a sample node set of the CTT specimen submodel wıth displacement boundary conditions. Figure 4 : Sample node set of the CTT specimen submodel wıth displacement boundary conditions . Before performing the experiments on the mode-I/III fracture test system, global assembly finite element and fracture analyses are perforned under 10 kN axial load with different loading angles (θ=0°, 15°, 30°, 45°, 60°, 75°, 90°) using ANSYS. Then, displacement conditions are transferred to FRAC3D [7] (solver of FCPAS – Fracture and Crack Propagation System) by using submodeling from the contact surfaces of the specimen. Having performed the FRAC3D analysis, which employs three-dimensional enriched finite elements, stress intensity factors (SIFs) are calculated along crack front. In Fig. 5, process map of the described analysis procedure is given.