PSI - Issue 19

Chihiro Sakamoto et al. / Procedia Structural Integrity 19 (2019) 513–519 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

518

6

3.2. Fatigue test results

Fig.6 shows fatigue life of the specimen. Nd is the fatigue life when a fatigue crack is detected. Nw is the fatigue life when the crack is propagated into web. N 30 is the fatigue life when the crack length reaches 30mm. In test part A (full length weld bead removal), no fatigue cracks were detected after 7.0Mcycles fatigue loading. In test Part C (half length of weld bead removal), a fatigue crack with the length of 3mm was detected after 1.0Mcycles fatigue loading. In test Part B ’ (one quarter length of weld bead removal), a fatigue crack with the length of 2mm was detected after 1.9Mcycles fatigue loading as shown in Fig.7. However, these cracks were not propagated until 3.0Mcycles fatigue loading. This is because that the stress was so small near the tip of removed weld bead as shown in Fig.5. After shaping up the tip of removed weld bead, no fatigue cracks were detected after 4.0Mcycles fatigue loading as shown in Fig.8. Nd is the crack detection life Nw is the crack propagation into web plate N30 is the crack length reaches 30mm

60

H G F

H ’

JRA, 2002 [7]

no retrofit fatigue life

N w Nd

N 30

50

full length removal

half one quarter one quarter half

no shape up

30 Δσ（ MPa ） 40

shape up

Bending stress Distribution

20

10 5

10 6

10 7

Fatigue life Nd ， Nw ， N 30 （ cycles ）

Fig.6 fatigue life of specimen.