PSI - Issue 14

7

K. Shridhar et al. / Procedia Structural Integrity 14 (2019) 375–383 Author name / Structural Integrity Procedia 00 (2018) 000–000

381

From the above analysis it is observed that SIF values are more critical for lesser radius ratios and shows significant change for smaller changes in crack length.

b

a

10 15 20 25 30 35

30

b

25

20

15

10

SIF in MP√m

FEM Analytical

FEM Analytical

SIF inMPaѵm

0 5

5

0

2

4

6

8 10 12 14

0

0

5

10

15

20

Crack length in mm

Crack length in mm

10 12 14 16

c

d

0 2 4 6 8

FEM Analytical

SIF in MPaѵm

0 2 4 6 8 10 12 14 16 18 20 22

Crack length in mm

Fig 4 , (a) SIF v/s Crack length for radius ratio 1.5 ;(b) SIF v/s Crack length for radius ratio 2; (c) SIF v/s Crack length for radius ratio 3.; (d) Von Mises stress plot of radius ratio 1.5 for 10 mm crack length.

Fig 4(d) shows Von Mises stress distribution plot of lug(radius ratio 1.5 )with 10mm crack length. It shows how critical is the stress distribution around the crack tip. In this case a maximum stress 682MPa was observed at the crack tip. 6.4. Fatigue life estimation of damaged lug The Fatigue crack growth life of the pin loaded lug joint with through the thickness crack emanating from the lug hole subjected to constant amplitude cyclic loading (R=0;P max =50KN) has been estimated by employing the Walker’s crack growth model. Radius ratio 1.5: From the fatigue crack growth curve it was observed that crack growth is stable up to 8 mm crack length and an average crack growth rate of 3Χ10 -5 mm/cycle was observed. There after crack growth rate i.e. slope of the curve goes on increasing rapidly for the next incremental crack lengths. From 8-16 mm average crack growth rate observed was 1Χ10 -4 mm/cycle. Radius ratio 2: It was observed that crack growth is stable up to 8 mm crack length and an average crack growth rate of 1Χ10 -5 mm/cycle was observed . There after crack growth rate i.e. slope of the curve goes on increasing