PSI - Issue 24

Bruno Atzori et al. / Procedia Structural Integrity 24 (2019) 66–79 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

76

11

10.00

Data normalised on the basis of Young's modulus of the material

≈7.25

N≈3500

0.10 Averaged strain energy density [MJ/m 3 ] As-welded, toe failure As-welded, root failure As-welded, toe failure As-welded, root failure 1.00

0.300

0.105

Steel welded joints (R 0 = 0.30 mm) 600 fatigue test data, load ratio R = 0-0.3 Aluminium welded joints (R 0 = 0.12 mm) 120 fatigue test data, load ratio R = 0

(b)

N A

0.01

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

Number of cycles to failure, N

10.00

As-welded, toe failure As-welded, root failure As-welded, toe failure As-welded, root failure

Steel welded joints (R 0 ≈ 0.3 mm) 600 fatigue test data, load ratio R = 0-0.3 Aluminium welded joints (R 0 = 0.12 mm) 120 fatigue test data, load ratio R = 0

0.10 Strain energy density Intensity Factor [kJ/m 2 ] ΔL A,50% = 0.035 kJ/m 2 N A = 2 ∙10 6 cycles Scatter Index (2.3%-97.7%): T L = 0.073/0.017 = 4.20 T σ = √T L = 2.05 Slope k = 1.75 1.00

Data normalised on the basis of Young's modulus of the material

0.073

≈0.056

SEDIF-based design scatter-band for steel as well as aluminium welded joints

0.035

0.017

(c)

N≈8.5 ·10 5

N A

0.01

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

Number of cycles to failure, N

Figure 3: (a) Fatigue test results relevant to welded joints made of steels and aluminium alloys and tested in the as welded conditions under axial or bending loading and re-analysed in terms of (a) and (b) averaged SED and (c) SEDIF parameter. Fatigue data in figures (b) and (c) have been normalized on the basis of Young’s modulus of the material (E = 206000 MPa for steels and 70000 MPa for aluminium alloys).