PSI - Issue 39

Hithendra Karakampalle et al. / Procedia Structural Integrity 39 (2022) 711–721 Author name / Structural Integrity Procedia 00 (2021) 000–000

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Fig. 13. Variation of SIF with crack length and interference Fig. 14. Percentage change in SIF, w.r.t zero interference Several parameters such as normal stress, hoop stress, contact pressure, degree of penetration, etc., were assessed to compare the relative effects of the interference levels at all crack lengths. Among them normal stress measured at the joint in the direction of application of load (σ x ) proved to be the best-suited one. Figure 15 shows the values of the maximum normal stress in the direction of application of load, for all crack lengths at all the interference levels considered in this study.

Fig. 15. Variation of the maximum normal stress (σ x, max ) at joint L2

It was observed that when a straight line is drawn from a given higher crack length and interference, towards the lower crack length, the straight line intersects the curve of lower interference at a lower crack length. For example, if a line is drawn from the normal stress value for a crack joint with an interference of 0.15% and crack length of 15 mm, it intersects the 0.1% interference curve at a crack length of 7 mm. This implies that the normal stress at the hole is same in both the cases. For another illustration, the normal stress at hole is same for 21 mm crack at 0.2% interference and 11 mm crack at 0.15% interference. Apart from the normal stress, the von Mises stresses measured at the hole and the loads encountered by the pins at the joint are equal in both cases. So, it can be deduced that for a given joint with relatively longer crack at higher interference, a joint with shorter crack and lower interference exists, where the stresses and load reactions are equal. 3.3. Case 3: Figure16 shows the variation of SIFs for different combinations of cracks at L1, L2 and L3 having 0% interference (snug fit) between plate and pins. For any given length of crack at location L2, presence of cracks at L1 and L3 yielded higher SIFs. Also, higher the size of neighbouring crack, greater is the increase in SIF at L2. The percentage change in SIF for a crack at L2 due to neighbouring cracks for the case of 0% interference is shown in Fig. 17.