PSI - Issue 28

Giovanni Pio Pucillo et al. / Procedia Structural Integrity 28 (2020) 2013–2025 GP Pucillo et al. – Part II / Structural Integrity Procedia 00 (2019) 000 – 000

2020

8

Normalized distance from hole edge

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

-350 -300 -250 -200 -150 -100 -50 0 50

0

5

10

15

-45° 1.0% -45° 2.0% -45° 4.0%

+45° 2.0% +45° 4.0% +45° 1.0%

θ = + 45

y

Radial residual stress [MPa]

x

θ = -45

Distance from hole edge [mm]

Fig. 9. Radial residual stress profiles along the direction at θ = ±45° for different percentages of cold expansion.

For the purpose of validating the single-hole 3-D FE model, the strain distribution surrounding the hole was investigated for the 2.0% CE. In detail, both radial and hoop stresses were evaluated at the end of the stages of hole expansion (maximum strains, because corresponding to the maximum diameter of the hole) and hole recovery (residual strains), along the directions at 0°, ±45°, and ±90° respect to rail longitudinal axis. Predicted maximum and residual strains as a function of the distance from hole edge are shown in Fig. 10 and Fig. 11, respectively.

30000

20000

10000

0

0

1

2

3

4

5

6

7

8

9

10

Strain [μ m/m]

-10000

-20000

+45°Radial +90°Radial +0°Radial -45°Radial -90°Radial

+45°Hoop +90°Hoop +0°Hoop -45°Hoop -90°Hoop

-30000

-40000

Distance from hole edge [mm]

Fig. 10. Maximum strain profiles along the directions at θ = 0°, θ = ±45°, and θ = ±90°.

20000

10000

0

0

1

2

3

4

5

6

7

8

9

10

Strain [μ m/m]

-10000

+45°Radial +90°Radial +0°Radial -45°Radial -90°Radial

+45°Hoop +90°Hoop +0°Hoop -45°Hoop -90°Hoop

-20000

-30000

Distance from hole edge [mm]

Fig. 11. Residual strain profiles along the directions at θ = 0°, θ = ±45°, and θ = ±90°.

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