Issue 35

M. Bozkurt et alii, Frattura ed Integrità Strutturale, 35 (2016) 350-359; DOI: 10.3221/IGF-ESIS.35.40 353 Figure 5 : Analysis procedure with a process map Results of Finite Element Models In this subsection, results from mode-I/III fracture analyses are presented for different loading angles and different specimen thicknesses. Deformed shapes and equivalent stress distributions are shown in Fig. 6 (θ=45° and t =25 mm). Figure 6 : Deformed shapes and equivalent stress distrubitions for θ=45°. As a demonstration case, Fig. 7 shows distributions of three-dimensional stress intensity factors for two different specimen thicknesses t =25 mm and t =12.5 mm (θ=45°). It can be seen from this figure that, when the thickness is reduced from 25 mm to 12.5 mm, mode-I SIF increases two times, while mode-II and mode-III SIFs increase nearly 3.5 and 2.5 times, respectively. The reason that mode-II and mode-III SIFs don’t increase 2 times as mode-I SIF is that mode-III loading causes the CTT specimen to bend in the tearing direction and that bending deflection and the moment of inertia do not change linearly with specimen thickness. Complete set of results for all loading angles for the two specimen thicknesses are shown in Figs. 8-10 in terms of mode-I, -II and –III stress intensity factors. It can be observed from these figures that mode-I stress intensity factor is maximum for pure mode-I loading conditions (θ=0°) and that it decreases with increasing loading angle until zero when θ=90°. In contrast to mode-I SIFs, mode-II and mode-III SIFs incerease with increasing loading angle. It can also be seen that for