PSI - Issue 21

C. Tekoğlu et al. / Procedia Structural Integrity 21 (2019) 2 – 11 C. Tekog˘ lu / Structural Integrity Procedia 00 (2019) 000–000

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2.2. Mode I test setups

Two di ff erent experimental setups were used to perform Mode I tearing experiments. The first setup, shown in Fig. 2a, is in fact a scaled down version of the setup designed by Simonsen and To¨rnqvist (2004). This setup was used to test the so-called Edge Crack Specimens (ECS), which were subjected to both tension and in-plane bending as illustrated in Fig. 2b. The initial notch length, a 0 = 50 mm, and the width, w = 200 mm, of the ECS specimens allow the crack to propagate 30 plate thicknesses for 5 mm-thick samples. The ratio of the crack growth length to the plate thickness increases with decreasing t , reaching a maximum of 300 for t = 0 . 5 mm. The initial height of the ECS specimens, H 0 = 248 mm, was observed to be large enough to minimize the influence of the far boundaries, an observation supported by El-Naaman and Nielsen (2013) who used a similar setup to test 2 mm-thick Al 1050 H14 plates. The second setup, shown in Fig. 2c, imposes pure uniaxial tension on Double Edge Notched Tensile (DENT) specimens, as illustrated in Fig. 2d (see also Pardoen et al., 2004; El-Naaman and Nielsen, 2013). For the DENT specimens, the initial notch length is a 0 = 45 mm, the initial height is H 0 = 100 mm, and the width is w = 180 mm. In these samples, two cracks grow toward each other over a 90 mm-ligament connecting the two notches. Both the ECS

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Fig. 2: The two setups used to perform Mode I tearing experiments in this study: the setup for tearing (a) the Edge Crack Specimens (ECS), and (b) the Double Edge Notched Tension (DENT) specimens. The dimensions for the (c) ECS specimens, which are subjected to combined tension and in-plane bending, are a 0 = 50 mm, w = 200 mm, and H 0 = 376 mm, and for the (d) DENT specimens, which are subjected to pure uniaxial tension, are a 0 = 45 mm, w = 180 mm, and H 0 = 220 mm .