Number of pages: 2

AP] ABDUL KALAM TECHNOLOGICAL UNIVERSITY
THIRD SEMESTER M.TECH DEGREE EXAMINATION, DECEMBER, 2017
Mechanical Engineering
(Machine Design)

01ME6110 Fracture Mechanics

Max. Marks : 60 Duration: 3 | lours
(Answer any two from each module)
Unless otherwise specified material properties may be assumed appropriately.

Part-A
1(a)Draw load —deflection curve of DCB specimen and obtain potential energy for each case 19
constant load (11)3 constant displacement (3)

1(b)Explain one of the differences in the R- curve for brittle and ductile material? Give the
two conditions for a crack to grow. (3)

1(0) Write down equations for the stress state corresponding to Mode |॥ loading

of an infinite plate . Draw the plastic zone shape (3)
2(a) Explain the behavior of semi elliptical crack growth in a pressure vessel (3)
2(b) ۱۷۷۲۵۲ kind of singularity describes a stress field near the vicinity ofa crack tip in (3)

LEFM? How differentiation of stress function is made possible.

2(0) Explain the importance on the results of a collinear cracks in an infinite long strip (3)

3(a) How Westergaard's stress function for biaxial stress field is applicable for mode-|
load case ? (3)

3(b)Determine the value of mode | SIF for the following cases

(a) Infinite plate with centre crack with 2a = 40 mm, thickness of the plate 2mm and far
field stress of 125MPa

(b) Infinite plate with edge crack with a 20 mm, thickness of the plate 2mm and far field
stress of 125MPa

(©) Strip with edge crack under bending, a= 20mm. depth, W = 50 mm. thickness,
B = 25 mmand bending moment, M = 1000 N-m, treat finite width correction factor as
1.09 (6)