PSI - Issue 66

María Moreno-Rubio et al. / Procedia Structural Integrity 66 (2024) 362–369 Author name / Structural Integrity Procedia 00 (2025) 000 – 000

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simple fatigue test at RT with R =-1 is represented using the equivalent maximum stress for R =0.1 obtained through the Goodman diagram. In Figure 2, the simple fatigue tests at RT are represented by blue circles, while those at HT are shown with red circles. Fretting fatigue tests at RT are depicted using blue triangles, and those at HT are marked with red triangles. In all cases, it can be observed that the fatigue life under both simple fatigue and fretting fatigue for high axial loads, around 1100 MPa, is very similar. This suggests that at such load levels, stress concentration from the contact between elements does not significantly affect fatigue. It is also worth noting that in simple fatigue, the effect of temperature is only significant for fatigue lives shorter than approximately 10⁵ cycles. In contrast, for fretting fatigue, the temperature effect is noticeable across all fatigue regimes, with fatigue life at HT being four times shorter compared to RT. For fretting fatigue, the fatigue limit is approximately 240 MPa at RT and 350 MPa at HT.

Table 3. Results of simple fatigue test at RT

Test number

R

f (Hz)

σ max (MPa)

σ max eq (MPa) ( R =0.1)

N f (Cycles) 7001 5815 42720 40663 128562 110410 322755 142585 156340 370509 418916 278023 5.00E6 228945 275483 275460 44213 54616 184767

1 2 3 4 5 6 7 8 9

-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1

10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10

1000 1000 850 850 700 700 600 600 600 550 550 550 500 500 500 500 1094 974 831

1200 1200 1096 1096 975 975 882 882 882 832 832 832 779 779 779 779

10 11 12 13 14 15 16 17 18 19

0.1 0.1 0.1

- - -

Table 4. Results of fretting fatigue test at RT

Test number

R

f (Hz)

N (kN)

σ max (MPa)

N f (Cycles)

1 2 3 4 5 6 7 8 9

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

8 8 8 8 8 8 8 8 8 8

10 10 10 10 10 10 10 10 10 10

900 650 650 575 450 400 350 320 320 275

33225 117619 108770 196902 431624 648348 900000 1.05E06 1.21E06 2.83E06

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