Issue 49

B. G. N. Muthanna et alii, Frattura ed Integrità Strutturale, 49 (2019) 463-477; DOI: 10.3221/IGF-ESIS.49.44





. . 2 F a 

k

(1)

IMax

Max

“  max ” is the maximum applied stress, “a” is the crack depth and “F” is the geometric function which depends of crack length, aspect ratio, as well as the type of applied load.

115

110

100 I (MPa.m 0.5 ) 105

95

90

 =5°  =20°  =35°  =50°  =65°  =80°

 =10°

 =15°

 =25°  =40°  =55°  =70°  =85°

 =30°  =45°  =60°  =75°

85

80

Stress intensuty factor K

75

0

20 40 60 80 100 120 140 160 180

Semi-elliptical angle  (°)

Figure 10: Mode I stress intensity factor of semi-elliptical surface crack in elbow versus angular crack  and for different angle position  (a/t =0.5, a/c =0.5, P =7 MPa).

(a)

(c)

(b)

(d) (e) Figure 11 : Stress distribution at semi-elliptical crack tip for 3 crack orientations. (a)  = 0°, (b)  = 45° and (c)  = 90°, (d ) definition of angular position  and, (e) shape of semi elliptical crack.

470