PSI - Issue 17

Sunil Bhat et al. / Procedia Structural Integrity 17 (2019) 21–28

28

S.Bhat et al/ Structural Integrity Procedia 00 (2019) 000 – 000

8

W

A

Y

900MPa ; 5 = =  = Y

570MPa

= W A

with c is shown in Fig. 6. \ Weld, W Back up steel, A

E E

MPa 2 10

Parent steel, A

2

1

Interface 1

Interface 2

A

A

W

.

2 int a

t =10 mm

2

1

int 

int 

1 int a

Stage II 2

Stage I 2

Stage I 1 Stage II 1

c = 52.73 mm

c = 62.32 mm

W

Y 

A

P r

c = 58.70 mm

c = 49.67mm

A

c = 58.70 mm

Y 

c = 49.67 mm

W

p r

c = 62.32 mm

c = 52.73 mm

Stage I 2 Stage II 2

Stage I 1 Stage II 1

c (mm)

c (mm)

Fig. 3. Stages of energy transfer ( t =10 mm)

Fig. 4. Strains at interfaces vs crack length ( t =10 mm)

2 # Nil effect of interface 1 ## Nil effect of interface 2

2

1

1

tip J erface int J applied J

applied K tip K

A

W

A

A

W

A

MPa m #

Stage I 1 Stage II 1

N/mm

Stage II 2

Stage I 1 Stage II 1

Stage I 2

Stage II 2

Stage I 2

#

##

##

c (mm)

c (mm)

Fig.5. Energy release rates vs crack length ( t =10 mm)

Fig.6. Stress intensity parameters vs crack length ( t =10 mm)

5. CONCLUSION Effect of strength mismatched interfaces between weld and steels over the crack tip is quantified under monotonic load with the help of a strain based analytical model. The energy release rate at the crack tip is lower than the remote value during weak-strong transition i.e. when the crack tip in parent steel approaches the interface of weld and is higher than the remote value during strong-weak transition i.e. when the crack tip in weld approaches the interface of back up steel. The shielding and amplification effects are maximum when the crack tip is at the interfaces. REFERENCES [1] Kim, A. S., Suresh, S. and Shih, C. F., 1997, Plasticity effects on fracture normal to interfaces with homogeneous and graded compositions. International Journal of Solids and Structures, 34, 3415-3432. [2] Predan, J., Gubeljak, N. and Kolednik, O., 2007, On the local variation of the crack driving force in a double mismatched weld. Engineering Fracture Mechanics, 74, 1739-1757. [3] Bhat, Sunil and Ukadgaonker, Vijay, G., 2015, A refined theoretical model for mode I crack near the interface of strength and plasticity mismatched materials in K dominant regime, International Journal of Damage Mechanics, 24, 1194-1213. [4] Bhat, Sunil, N. Suresh, Kambar, M. M. and Ukadgaonker,V.G., 2017, Strain based investigation of mode I crack near strong-weak interface in SSY regime, International Journal of Mechanical Sciences, 123, 224-237.