PSI - Issue 42

Denny Knabner et al. / Procedia Structural Integrity 42 (2022) 561–569 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

565

5

Real-life component connection

Laboratory model

ǡƒ

Abstraction

Figure 3: Abstraction of the real-life component contact with the flat-pad setup. Due to the double actuation and the slip control, the slip condition at the point of failure of the realistic component connection can be reproduced. With the setup presented, the fretting-fatigue strengths ( ) shown in Figure 4 were determined using the progressive-load method as presented in [33] for certain combinations of and (coloured bars). The stress ratio was = 0.03 , as in the connecting-rod tests Plain fatigue strength Fictitous extrapolation points

386.9

386.9

0 100 200 300 400 Fretting fatigue strength (MPa) 386.9

270.2

270.2

270.2

183.8

164.3

164.3

241.9

236.7

237.3

15

10

5

20 Nominal contact pressure (MPa) 40

0

60

Figure 4: Experimentally determined fretting-fatigue strengths for different combinations of slip amplitude and contact pressure As can be seen, permutations of the parameters = 5, 10, 15 µm and = 20, 40, 60 MPa were used. The green bars on the left edge of the diagram represent the plain-fatigue strength at a contact pressure of = 0 MPa according to Table 1. On the axis with 5 µm slip amplitude and variable contact pressure, the behaviour presented in Figure 1b can be clearly observed. As the contact pressure increases (from 0 to 20 MPa ), the fretting-fatigue strength initially drops sharply. Above a limit value of the contact pressure ( 20 MPa ), there is no further decrease in the fretting-fatigue strength with further increase of . This behaviour can also be recognized for the existing results at = 10 µm . Furthermore, for the tests with = 20 MPa and variable slip amplitude, the U-shaped behavior presented in Figure 1a can be recognized, with a minimum occurring at = 10 µm . It can be seen that some points