PSI - Issue 28

Buşra M. Baykan et al. / Procedia Structural Integrity 28 (2020) 2055 – 2064 Baykan et al./ Structural Integrity Procedia 00 (2019) 000–000

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Next, the variation of normal stresses along the paths shown in Fig. 1. are calculated. PD results are compared with FEA and results in Özaslan et al. (2019) in Fig. 6. It is seen that, the PD results are identical with FEA and the results in Özaslan et al. (2019) for OHT-1 specimen. The PD results in agreement with FEA and Özaslan et al. (2019) for OHT2-1. FEA results are nearly overlaps Özaslan et al. (2019) for all specimens. The PD results of normal stresses between the holes deviate from FEA and Özaslan et al. (2019). for OHT2-1 and OHT2-2 specimens. However, the shape of the normal stress profiles for OHT2-1 and OHT2-2 specimens are in agreement with FEA and Özaslan et al. (2019).

Fig. 6. Comparison of PD and FEA results of normal stress along the paths with Özaslan et al. (2019).

The variation of normal strains in the middle of the plates with respect to y coordinate are obtained using PD and FEA as shown in Fig. 7. The PD and FEA results are in very good agreement for OHT1 specimen. It is seen that, the FEA solution yields higher normal strain values around the hole for OHT1 specimen. The PD strains away from the holes are identical with FEA for OHT2-1 and OHT2-2 specimens and the discrepancy between PD and FEA increase around the holes.

Fig. 7. PD and FEA results of normal strains in loading direction.

The PD displacements in y and x directions as a function of y and x coordinates on the lines at 0 y  respectively of the plate are compared with FEA in Figs. 8a. and 8b., respectively. The PD displacement profiles in Fig. 8. overlap FEA results. The comparison PD displacement contours in y and x directions are given in Fig. 9. and Fig. 10., respectively. PD displacement fringes of all specimens are in very good agreement with FEA results. The initiation and propagation of cracks in the OHT1, OHT2-1 and OHT2-2 specimens subjected to uniaxial tensile load is calculated using PD. The evolution of the cracks is illustrated in Fig. 11. It is observed that, the cracks initiate around the holes where the normal stresses are maximum as seen Fig. 5. For the specimens with double holes (OHT2 1 and OHT2-2), the crack propagates between the holes and then propagates through the free edges. 0 x  and