References

Fri, 07 Jul 2017 | Aluminium Structures

B.8.1 AW guidance on assessment of the fitness for purpose of welded structures. IIW Draft for Development doc. SST-1157-90.

B.8.2 Guidance on some methods for the derivation of acceptance levels for detects in fusion welded joints. British Standard Published Document 6493:1991.

B.8.3 Standard test method for measurement of fatigue crac k growth rates, ASTM E647-93.

B.8.4 Fatigue crack propagation in aluminium, IIW Document XIII-B77-90.

B.8.5 Stress intensity factor equations for cracks in three-dimensional finite bodies. ASTM STP 791, 1983, ppI-238-1-265.

B.8.6 Graf, U: 'Fracture mechanics parameters and procedures for the fatigue behaviour estimation of welded aluminium components1, 1992.

B8.7" Simulations of short crack and other low closure loading conditions utilising contact Kmax AK-decreasing fatigue crack growth procedures. ASTM STP 1149-1992, pp.197-220.

Table B.7.1. Predicted inital crack length ai for various stress ranges at 2 x 106 cycles

a) Wrought aluminium alloys

Upperbound fatigue crack growth data from tables B.2

¡.3 and B3.5.

Stress Range

Uniform Tension

Kt=3.0, Dt=2.0mm, DCF5]

Stress intensity ratio R:

0,1

0,8

0,1

0,8

N/mm2

mm

mm

mm

mm

16

8,57

6,68

6,28

4,06

20

6,63

4,79

4,00

1,99

25

4,82

3,00

2,19

0,266

25"

-

-

0,11

0,11

31

3,22

1,42

0,44

0,07

31i)

-

1,42

0,051

0,051

39i)

1,24

0,52

0,025

0,025

49"

0,30

0,26

0,014

0,014

62"

0,14

0,13

0,0073

0,0073

77"

0,078

0,075

-

-

96"

0,042

0,042

-

-

121"

0,023

0,023

-

-

Note 1: FCGR: WAA K^ thickness of 12mm

„ 10MPa(m)°'5 one

single phase, i.e. FCG from a; up to the plate

b) Cast aluminium alloys

Upperbound fatigue crack growth rate from table BJ.^

•

Stress Range

Uniform Tension

K,=3.0, Dt=2.0mm, DCF5]

Stress intensity ratio R:

0,1

0,8

0,1

0,8

N/mm2

mm

mm

mm

mm

16

11,99

6,46

11,99

3,33

20

11,88

4,49

11,56

1,83

25

10,99

2,97

9,09

0,391

31

8,87

1,92

5,90

0,200

39

6,51

1,17

3,32

0,1067

49

4,48

0,71

0,072

0,062

62

2,86

0,42

0,036

0,035

77"

1,80

-

-

-

77

0,295

0,259

0,022

0,0219

96"

1,082

-

-

-

96

0,162

0,159

-

-

121"

0,621

-

-

-

121

0,096

0,095

-

-

Note 1: FCGR CAA R constant, R = 0,1,1 single phase, ie FCG from a, up to the plate thickness of 12mm

Table B.7.2 Fatigue life predictions based on upperbound fatigue crack growth data for wrought aluminium alloys from tables B .3.3 and B3.5

a) Uniform tension - Phase 2

Type of FCGR:

R=Kmm/Kmax = constant

Kmax = 10MPa(m)°'5 constant

Stress intensity ratio R:

0,1

0,8

0,1

0,8

Crack

Stress

Fatigue

Fatigue

Fatigue

Fatigue

length,

intensity

life,

life,

life,

life

ai

range,

mm

MPam0,5

cycles

cycles

cycles

cycles

12,00

13,88

-

-

-

-

11,00

12,97

1 428

3

1 411

2

10,00

12,03

3 172

8

3 131

6

9,00

11,08

5 347

17

5 271

15

8,00

10,12

8 123

37

7 996

40

7,00

9,16

11 749

80

11 545

110

6,00

8,20

16 614

185

16 293

336

5,00

7,25

23 258

464

22 854

1

163

4,00

6,30

33 728

1 312

32 319

4

295

3,00

5,31

61 317

3 452

46 887

12

007

2,00

4,25

149 999

16 791

71 997

33

860

b) Stress gradient - Phase 2

Type of FCGR:

R Kmin/ICmax

= constant

Kmax= 10MPa(m)°'5

constant

Stress intensity ratio R:

0,1

0,8

0,1

0,8

Crack

Stress

Fatigue

Fatigue

Fatigue

Fatigue

length,

Intensity

life,

life,

life,

life,

Range,

mm

MPam05

cycles

cycles

cycles

cycles

12,00

15,61

-

-

-

-

10,00

14,65

2 027

2

2 009

1

9,00

14,00

3 214

3

3 184

2

8,00

13,26

4 580

6

4 535

3

7,00

12,42

6 196

10

6 130

6

6,00

11,51

8 166

17

8 070

12

5,00

10,51

10 655

31

10516

28

4,00

98,42

13 950

64

13 745

77

3,00

8,19

18618

158

18 303

275

2,00

6,72

26 049

547

25 524

1 590

Table B.73. Fatigue life predictions based on upperbound fatigue crack growth data for cast aluminium alloys from table B3.4 and wrought alloy AA 6005A-T6 from table 8.3.2(a)

a) Uniform tension - Phase 2

Type of FCGR:

CAA R-Kmin/Kmax —

constant

AA6005A R=Kmii/Kmax =

constant

Stress intensity ratio R:

0,1

0,8

0,1

0,8

Crack

Stress

Fatigue

Fatigue

Fatigue

Fatigue

length,

intensify

life,

life,

life,

life

a¡

range,

cycles

mm

MPam0'5

cycles

cycles

cycles

12,00

13,88

-

-

-

-

11,00

12,97

2'016

0

2 725

11

10,00

12,03

4'670

0

6 092

47

9,00

11,08

8'267

0

10 346

172

8,00

10,12

13'294

1

15 849

681

7,00

9,16

20*552

4

23 148

3 031

6,00

8,20

32*302

16

33 107

8 369

5,00

7,25

57*146

63

50 251

16 049

4,00

6,30

116*025

312

96452

27 648

3,00

5,31

279'046

1*692

246958

46 490

2,00

4,25

938*072

6*154

997 170

83 056

b) Stress gradient - Phase 2

Type of FCGR:

CAA R=Kmin/Kmax = constant

AA6005A R=Kmin/Kin„

= constant

Stress intensity ratio R:

0.1

0.8

0.1

0.8

Crack

Stress

Fatigue

Fatigue

Fatigue

Fatigue

length,

intensity

life,

life,

life,

life,

a¡

range,

mm

MPam0,5

cycles

cycles

cycles

cycles

12,00

15,61

-

-

-

-

11,00

15,19

1 182

0

1 808

1

10,00

14,65

2517

0

3 793

3

9,00

14,00

4 081

0

6 035

7

8,00

13,26

5 978

0

8 636

16

7,00

12,42

8 367

0

11 742

38

6,00

11,51

11 505

0

15 572

109

5,00

10,51

15 835

1

20477

383

4,00

9,42

22 202

3

27 074

1 776

3,00

8,19

33 164

13

36 609

6 769

2,00

6,74

64 980

94

59496

15 333

Table B.7.4. Fatigue life predictions based on upperbound fatigue crack growth data for wrought aluminium alloys from table B.3.3. and wrought alloy AA 6005A-T6 from table B.3.2.(b)

a) Uniform tension - Phase 1

Type of FCGR:

WAA Kmax 10MPa(m)°'5 const.

AA6005A K,,^ 10MPa(m)0-5 constant

Stress intensity ratio R:

0,1

0,8

0,1

0,8

Crack

Stress

Fatigue

Fatigue

Fatigue

Fatigue

length,

intensity

life,

life

life,

life,

ai

range,

mm

MPam0'5

cycles

cycles

cycles

cycles

2,05

4,30

-

-

-

-

1,85

4,07

7 139

7 527

14 355

13 409

1,65

3,83

15 518

16 395

31 119

29 712

1,45

3,58

25 527

27 031

51031

49 116

1,25

3,32

37 759

40 089

75 212

72 732

1,05

3,03

53 169

56 627

105 451

102 341

0,85

2,72

73 424

78 502

144 855

141 042

0,65

2,38

101 802

109 388

199471

194 885

0,45

1,98

146 015

158 005

283 365

278 004

0,25

1,47

231 455

253 422

444 329

438 619

0,05

0,66

5 561 901

5 604 650

19 522 952

19 515 242

b) Stress Gradient - Phase 1

Type of FCGR:

WAA K^ 10MPa(m)0,5 const.

AA6005A Kmax 10MPa(m)0'5 constant

Stress intensity ratio R:

0,1

0,8

0,1

0,8

Crack

Stress

Fatigue

Fatigue

Fatigue

Fatigue

length,

itensity

life,

life

life,

life,

aj

range,

mm

MPam0,5

cycles

cycles

cycles

cycles

2,05

6,82

-

-

-

-

1,85

6,70

1 905

673

3 995

2 335

1,65

6,61

3 877

1 395

8 124

4 760

1,45

6,55

5 923

2 170

12 405

7 290

1,25

6,48

8015

2 978

16 778

9 883

1,05

6,36

10 188

3 847

21 316

12 591

0,85

6,08

12 553

4 869

26 240

15 567

0,65

5,71

15315

6 243

31 964

19 112

0,45

5,14

18 765

8 350

39 063

23 666

0,25

4,10

24 176

13 294

50 033

31 961

0,05

1,99

42 254

32 843

85 148

66 467

Table B.7.5. Fatigue life predictions based on upperbound fatigue crack growth data for cast aluminium alloys from table B.3.4.

a) Uniform tension - Phase 1

Stress intensity ratio R:

0,1

0,8

Crack

Stress

Fatigue life,

Fatigue life,

length,

intensity

ai

range,

mm

MPa(m)0'5

cycles

cycles

2,05

4,30

-

-

1,85

4,07

398 937

1 736

1,65

3,83

1 154 022

4 119

1,45

3,58

2 688 305

7 506

1,25

3,32

7 563 667

12 541

1,05

3,03

99 972 200

20 495

0,85

2,72

3,630109E+09

34 172

0,65

2,38

3,462941E+11

60 895

0,45

1,98

1,719760E+14

125 648

0,25

1,47

3,335859E+18

1 3278 202

0,05

0,66

1,680181E+30

6,315015E+12

b) Uniform tension - Phase 1

Stress intensity ratio R:

0,1

0,8

Crack

Stress

Fatigue life,

Fatigue life,

length,

intensity

ai

range,

mm

MPa05

cycles

cycles

2,05

6,82

-

-

1,85

6,70

11 723

47

1,65

6,61

24 415

101

1,45

6,55

38 268

165

1,25

6,48

52 852

235

1,05

6,36

68 809

319

0,85

6,08

88 282

442

0,65

5,71

116 339

685

0,45

5,14

163 937

1 100

0,25

4,10

335 864

2 136

0,05

1,99

1,638740E+13

17 145

0 0
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