PSI - Issue 22

S.M. Xie et al. / Procedia Structural Integrity 22 (2019) 353–360 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

359

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Table2 The analysis of stress state level assessment based on IIW-2008 standard Serial number Calculated   FAT level [6] Allowable   Stress factor

Stress level

weld 1

9.624

36 28 36 36 36 36 28 36 28 36

21.1 16.4 21.1 21.1 21.1 21.1 16.4 21.1 16.4 21.1

0.456 0.501

low low low low low low low low low

weld 2

8.225

0.39

weld 3 weld 4 weld 5

13.467 13.499

0.638 0.640 0.321 0.811 0.681 0.711 0.553

6.78

medium

weld 6

14.376

weld 7

11.665

Using the IIW-2008 standard, the FAT grade of weld 2 was raised from 28 to 36, and the allowable fatigue strength value was increased from 16.4MPa to 21.1MPa. At this time, the stress factor was reduced from 0.501 to 0.39, and the stress state level was unchanged; The FAT grade of weld 6 was adjusted from 28 to 36, and the allowable fatigue strength value was increased from 16.4MPa to 21.1MPa. At this time, the stress factor was reduced from 0.811 to 0.681, and the stress state level was lowered from medium to low; The FAT grade of the weld seam 7 was adjusted from 28 to 36, and the allowable fatigue strength value was increased from 16.4MPa to 21.1MPa. At this time, the stress factor was reduced from 0.711 to 0.553, and the stress state level was unchanged. The results of the analysis are shown in Table2. Using the DVS1608-2011 standard evaluation procedure in Section2.2, the directional stress extremum, the stress ratio and the stress amplitude of the evaluated position in the local coordinate system of the weld under all fatigue conditions can be obtained. The weld notch curve value and the allowable fatigue strength amplitude of the welded joints can be determined according to the form and load-bearing condition of the welded joints. The evaluation results of these typical weld stress state levels are shown in Table3. The analysis results of weld joint type, notch curve index x and load-bearing capacity are given in the table. It can be seen from Table3 that the stress factors of these typical welds are less than 0.75, and their stress state levels are all low.

Table3 The analysis of stress state level assessment based on DVS1608 standard

Parallel to weld direction

Vertical to weld direction

Accuracy grade of weld

Along the weld plane

x

Stress level

Serial number

Type of joints

v a

 a

x a

y a

  azul R

  azul R

  azul R

 // 

  

 // 

A5 lap weld

CPB

20

28.279

0.486

28.131

0

18.055

0

0.486

low

weld 1

CPA

21 23

32.319 18.663

0.072 0.125

34.162 19.728

0.073 0.126

18.070 18.069

0 0

0.126 0.218

low low

DHV fillet weld Double fillet weld

weld 2

CPC2

weld 3

CPC2

21

28.922

0.051

28.503

0.075

18.081

0.079

0.135

low

HV fillet weld HY fillet weld

weld 4

CPC2

25

38.005

0.471

37.936

0.026

18.049

0.192

0.52

low

weld 5

CPC2

41

28.161

0.567

37.991

0.006

18.111

0.023

0.57

low

CPB

12

28.235

0.071

37.755

0.416

18.291

0.017

0.456

low

V butt weld

weld 6

CPC2

16 15

25.1

0.08

33.564 29.892

0.468 0.112

18.291 19.564

0.017 0.032

0.513 0.219

low low

CPB

29.942

0.138

V butt weld

weld 7

CPC2

41

8.536

0.484

8.521

0.392

19.564

0.032

0.761

medium