PSI - Issue 38
Isabel Huther et al. / Procedia Structural Integrity 38 (2022) 466–476 Author name / Structural Integrity Procedia 00 (2021) 000 – 000
475
10
c Figure 10. Fatigue results (a) overload of 1 YS, (b) overload of 1.25 YS, (c) overload of 1.56 YS [6]
6.3. Residual stresses versus fatigue cycles The Table 3 gives the residual stress measurements during fatigue tests for three overload levels 1 YS, 1.2 YS and 1.56 YS [6]. After overload, a residual stress relaxation was observed or an introduction of compression at the weld toe. The introduction of compression is variable depending on the weld toes with differences greater than 350 MPa before and after overload. During fatigue tests, the residual stresses are constant or increase in compression, or level off in compression.
Table 3. Residual stress measurement during fatigue tests [6] after overload (MPa ± 25MPa) local overload after overload (MPa ± 25MPa)
after fatigue test (MPa ± 25MPa)
after fatigue test (MPa ± 25MPa)
fatigue
fatigue
Direction L
Direction T
Direction L
Direction T
Direction L
Direction T
Direction L
Direction T
Specimen
Point
1
87
271
-83
0
-197
-11
-
-
2
137
107
23
11
-87
77
-
-
3
138
15
50
0
-38
86
-
-
14
1.56 YS
4
0
94
0
-10
-40
-102 12,5
- - -
- - -
Failed to
60 000 cycles
mean
91 65 82
122 107
-2,50 57,43
0,25 8,58 -265
-90,50 74,52
119 959 cycles (zone 4)
std
87,99
-248
-214
-351
-228
-204
1
91
2
9
143
14
0
-17
-89
7
57
3
56
180
40
88
0
55
65
160
36
4
197
-26
190
-18
43
-44
184
67
1.25 YS
44 000 cycles
88 000 cycles
mean
86 80
97 90
-1,00
-48,75 151,42
-47,00 114,16
-107,25 173,28
7,00
20,00
std
182,02
173,13
156,37
1
141
193
-65
-104
-61
-313
-
-
2
-28
-60
-56
-104
-64
-286
-
-
3
290
232
125
-12
121
-27
-
-
50
1. YS
4
79
165 133 131
58
0
37
89
- - -
- - -
50764 cycles (zone 2)
Failed at
50 000 cycles
mean
121 133
15,50 91,99
-55
8,25
-134,25 196,91
std
56,79
88,61
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