PSI - Issue 60

Thondamon V et al. / Procedia Structural Integrity 60 (2024) 484–493 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

486

3

elbow specimens consisted of a 90° bend and two attached equal length straight pipes terminating at stiff flanges. Bend radius ratio of the elbows is 3.0 (ratio between bend radius of the elbow and the cross-sectional radius of the elbow). The elbow factor or pipe bend characteristics (h = t R / r02) varied from 0.43 to 0.46. Elbow factor is used to characterize the bend geometry of the elbow using a single parameter which incorporates the influence of wall thickness, bend radius and mean radius of the elbow. Typical set-up used for the fracture tests is shown in Fig. 2. The elbows are supported in a hinge-hinge condition. The lower end of the elbow is attached to a hinge which is fixed to the base fixture connected to the test floor. The upper end of the elbow is attached to a hinge which is fixed to the actuator. The servo-hydraulic actuator is attached to a reaction frame. The distance between the vertical line joining the hinges and the center of elbow was considered as the lever arm distance. For the four elbows tested with internal pressure, the elbows were filled with water through the threadolets provided in the elbow specimens. Five elbows with 219 mm outer diameter were tested using ±1000 kN capacity servo-controlled hydraulic actuator and the two elbows with 610 mm outer diameter were tested using servo-controlled hydraulic actuator of ±2000 kN capacity. Static monotonic load under opening mode was applied on the elbows. The tests were conducted under displacement control. The rate of displacement was 0.05 mm/s for the five elbows with 219 mm outer diameter and 0.04 mm/s for the two elbows with 610 mm outer diameter. During the experiments, various responses such as load-line displacement, surface crack length, crack mouth opening displacement were measured. All the data were acquired through a high-speed data logger which was interfaced to a computer system for on-line data acquisition.

Table 1. Geometric details of elbow specimens and crack parameters. Outer Diameter Thickness

Mean radius

Bend radius

Notch length

Notch width

Notch angle

Elbow ID

OD (mm)

t (mm)

r0 (mm)

R (mm)

2c (mm)

w (mm)

2 θ (deg)

ELHO-8 [3]

219

14.5

102.3

328.5

-

-

-

ELHO-24-4 [5]

610

39.8

285.1

915.0

-

-

-

PRELHO-8 [3]

219

13.9

102.6

328.5

-

-

-

ELTWCIN-24-3 [5]*

610

39.7

285.2

915.0

630

4.0

118.3

PRELTWCIN 8-1 [4]*

219

13.9

102.6

328.5

171

3.0

89.5

PRELTWCIN 8-3 [4]*

219

14.3

102.4

328.5

285

3.5

149.1

HPRELTWCIN 8-1 [4]*

219

13.8

102.6

328.5

170

3.0

89.0

*: Through-wall notch was located at the intrados and aligned in the circumferential direction.

Fig. 1. Details of typical elbow specimen with circumferential through-wall notch at intrados.